Histopathology of the human adrenal cortex

2

Histopathology of the Human Adrenal Cortex A. MUNRO NEVILLE M. J. O'HARE

The pathological features of the human adrenal cortex are among the best understood in endocrinology, due, in no small measure, to the detailed correlation of morphology and steroid biosynthesis which has been. undertaken by numerous research groups during the past 20-30 years. In this chapter, we give a concise account of its structural and functional pathology. STRUCTURE OF THE HUMAN ADRENAL CORTEX

The normal adult gland weighs between 4 and 5 g when removed at operation and, on average, 6 g at autopsy, the difference being due to the effect of adrenocorticotrophic hormone (ACfH) released in response to terminal stress (Symington, 1969). Both glands are of similar size. Sex differences are not apparent. Each gland consists, in section, of an outer yellow cortex and an inner pearly-grey medulla, the latter restricted predominantly to the head and body of the gland (Dobbie and Symington, 1966). The cortex consists of three anatomical zones: an outer zona glomerulosa, an inner zona reticularis and, between them, the zona fasciculata (Figure la). In the normal human gland, zona glomerulosa cells are found in a series of irregular focal nests around the periphery of the cortex beneath the connective tissue capsule. Cytologically, they are small with a high nuclear/cytoplasmic ratio and contain only moderate amounts of lipid, in contrast to the large lipid droplets of zona fasciculata cells (Figure 1). The preparation of paraffin sections results in the extraction of lipid giving fasciculata cells a vacuolated appearance. Hence the term 'clear' cells being applied to the columns of these cells which extend from the zona reticularis to the zona glomerulosa or, where the latter is absent, to the capsule itself. The zona reticularis consists of anastomosing cellular cords separated by thin-walled sinusoids. Its cells have a relatively lipid-sparse cytoplasm (hence the term 'compact' cells) and they contain numerous lipofuscin granules (Figure 1). Clinics in Endocrinology and Metabolism-Vol. 14, No.4, November 1985

791

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(a) Figure I. The normal human adrenal cortex. On the left (a) is a normal gland (weighing 3.7 g) removed at surgery from a subject with metastatic breast cancer. The outer zona glomerulosa has a focal distribution beneath the capsule with thc zona reticularis occupying thc inner quarter of the cortex. The clear cells of the zona fasciculata comprise the remainder. On the right (b) may be seen the effect of ACfH administration. Compact lipid-rich cells extend outwards to almost reach the capsule. The cortex is broadened and the gland is of increased weight [Haematoxylin and eosin (H&E): a xS-t, b X63].

The distinctive ultrastructure of these various cell types has been the subject of many studies (for details, see MacKay, 1969; Tannenbaum 1973; Neville and O'Hare, 1982). Such work has, however, not added greatly to our understanding of the various functional pathological features and will not, therefore, be mentioned further. FUNCTIONAL ZONATION AND THE EFFECTS OF ACTH The morphology of most adrenocortical lesions can be most readily interpreted on the basis of the effects of ACTH on the normal adrenal cortex and its functional zonation. (For a review of possible mechanisms of functional zonation, see Neville and O'Hare, 1982; Hornsby, 1985.) The zona glomerulosa is responsible exclusively for the production of aldosterone and is responsive to both angiotensin and potassium. The role of other putative glomerulotrophins is, as yet, unresolved. The zona fasciculata and zona reticularis both produce glucocorticoids and sex hormones (mainly Cwsteroids). The compact cell zona reticularis, however, is associated with a higher output of C 19 and sulphated steroids such as de hydro iso-

HISTOPATHOLOGY OF THE HUMAN ADRENAL CORTEX

793

androsterone sulphate (DHAS), although they are also formed to a lesser extent by the clear cell zona fasciculata (O'Hare et aI, 1980; Hyatt et al, 1983). There is, as yet, no convincing proof of a separate adrenal androgen-stimulating hormone. In steroid biosynthetic terms, all cell types respond to ACTH although the effect is more marked on zona fasciculata cells. On these bases, it is possible to understand the morphological and biochemical changes induced by ACTH administration and the changes which occur in the various ACTH-dependent adrenal lesions. The acute administration of ACTH results in an immediate increase in steroid hormone output. More prolonged ACTH administration results in an increase in the weight of the gland with a broadening of the cortex. The precise mechanisms of cortical growth still remain poorly understood (Neville and O'Hare, 1982; Hornsby, 1985). Commencing from the innermost aspect of the zona fasciculata, ACTH causes the clear cells to lose their lipid and become converted to compact-type cells. The zona reticularis appears to extend outwards and compact cells may, depending on time and the amount of ACTH, reach the zona glomerulosa, or the capsule where this zone is absent (Figure Ib). These changes occur concomitantly with a continued raised output of steroids. Similar changes occur in response to stress (Symington, 1969). When the stress recedes and ACTH levels fall, the cortex gradually returns to normal with clear cells reappearing first deep in the cortex at the junction of the zona reticularis and zona fasciculata, thereafter extending outwards. This process sometimes leaves a 'cap' of compact cells under the zona glomerulosa/capsule (the so-called 'reversion' pattern). The adrenal cortex at autopsy is often influenced by these processes leading to an apparently atypical appearance in otherwise normal glands.

VASCULATURE AND NEURAL SUPPLY Blood and lymphatic supply The vascular supply to the adrenal gland plays a vital role in determining certain aspects of functional zonation of the cortex and possibly also its growth. The adrenal glands are each supplied with blood via many small arteries which enter the capsule to give rise to an extensive subcapsular arterial plexus. The essential feature of the cortical blood supply is the lack of a significant direct arterial supply to the deeper layers (zona fasciculata and zona reticularis) of the cortex. From the subcapsular plexus, capillaries pass directly through the cortex between the columns of zona fasciculata cells eventually forming an interlocking plexus of capillary sinusoids surrounding the zona reticularis cells. Effluent cortical blood normally passes directly into sinusoids in the medulla and thence into the large central vein, which it enters via small venules between the unique, typically eccentric, longitudinal muscle bundles in its wall (Dobbie and Symington, 1966). The central vein is notably invested with an invaginated cuff of cortical tissue.

794

A. M. NEVILLE AND M. J. O'HARE

Lymphatics are limited to the capsule of the gland and the adventitiae of the central vein and its main tributaries. The cortex itself is devoid of lymphatics. Nervous supply Cortical cells are not thought to be directly innervated. The adrenal gland, as a whole, however, has a very rich autonomic nervous supply. It is concerned not only with the functional activity of the medullary phaeochromocytes but also with regulating adrenal blood flow which is probably important for both cortical function and growth. ADRENOCORTICAL NODULES Adrenocortical nodules are frequently encountered lesions which occur not only in the absence of adrenal functional abnormalities but also in association with a variety of adrenal-induced and adrenal-associated disorders (Neville, 1978). They still cause pathologists diagnostic and interpretative difficulty. It is important to distinguish them from the morphologically similar, but much rarer, neoplastic lesions which are usually associated with some form of overt hypercorticalism (see later). They are rarely diagnosed in life but can sometimes be detected by computed tomography (Cf) scans (Prinz et al 1982). In normotensive subjects, they may be recognizable macroscopically and usually bilaterally in up to 3% of adrenals. Their frequency and size increase with age and in hypertension (Russell et al 1972). Micronodular changes, however, are seen in at least two-thirds of adrenals in normotensive adult subjects. The earliest abnormality appears to be a microscopic rounded lesion, usually yellow in colour, situated wholly within the cortex towards its periphery or in the centre of the gland in relation to the main vein (Figure 2). As they enlarge, the surrounding tissue is compressed until they eventually form mushroom-like masses protruding through the capsule or expand within the gland to form a large (2-3 em) lesion (Figure 2). Such lesions have, in the past, been called 'non-functioning' adenomas, adenomatous hyperplasia, nodular hyperplasia and, when small, micronodular hyperplasia. In some series, the difference between an adenoma and a nodule has been taken to be one of size, nodules being defined as less than 0.8 em diameter and adenomas as more than 0.8 cm diameter (e.g. Granger and Genest, 1970). All such terms are best disregarded as it is likely that all such lesions are the result of the same process and that time may be the important factor in size determination. They are all, in our opinion, simply best referred to as nodules, best regarded as a variation of adrenal structure, and as localized overgrowths predominantly associated with the aging process. Histologically, nodules usually consist of clear lipid-laden cells similar in size and appearance to those of the normal zona fasciculata. The cells are arranged in cords and clusters separated by prominent fibrovascular

HISTOPATHOLOGY OF THE HUMAN ADRENAL CORTEX

795

Figure 2. The nodular adrenal gland. Several nodules are present in one gland. They range from 3 em in diameter down in size. Some are found entirely within the gland; others project from one pole (xO.6).

trabeculae (Figure 3). Rarely, so-called 'non-functioning black nodules', composed of lipofuscin-rich compact cells, may be found. Larger nodules at autopsy may reveal a variety of further morphological changes including extensive areas of fibrosis, hyalinization, and even myxomatous change. Occasionally numerous dilated sinusoidal spaces are present imparting an angiomatous appearance, and into which haemorrhage may occur to cause one type of cystic change. Nodules are also a

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HISTOPATHOLOGY OF THE HUMAN ADRENAL CORTEX

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favoured site for metastatic carcinoma and infective lesions such as tuberculosis. Larger nodules, particularly after prolonged stress, may reveal areas of myelolipomatous change and even osseous metaplasia. There is still dispute as to the functional and pathological importance of nodules. Dobbie (1969) believes that they result from vascular damage. He noted a high incidence of hyalinization and intimal proliferation with luminal obliteration in the capsular arteries of nodule-containing adrenal glands, and has proposed that the resulting ischaemia causes focal cortical atrophy. The arteries accompanying the central vein are apparently less compromised by the arteriopathy so that those central cortical cells may be able to undergo hyperplasia to form nodules and come to fill the ischaemic outer cortical defect. This might account for the high frequency with which nodules are related to the central vein. The problem remains, however, of why they do not invariably cause hypercorticalism, or at least atrophy of the attached cortex, as their weight often exceeds that of the normal gland. Nodules can produce steroids in vitro (Symington 1969; Honn et aI, 1977) and respond to ACfH in culture with glucocorticoid secretion (Neville and O'Hare, 1982). Nevertheless, no specific derangement of corticosteroid metabolism has ever been demonstrated in vivo in the absence of concomitant hyperplastic changes in the uninvolved cortex. The fact that the clear cells of nodules frequently fail to respond to ACTHlstress with compact cell conversion suggests that they may in some way be isolated functionally from the remainder of the cortex, and thus not contribute significantly to steroid output.

ADRENOCORTICAL OVERACTIVITY Hyperfunction of the adrenal cortex may be associated with either hyperplasia, or benign or malignant neoplasms. Hyperplasia is in our experience always bilateral; neoplasia almost always unilateral. There are three principal forms of adrenocortical hyperfunction, namely Cushing's syndrome (excess production of glucocorticoid hormones, characteristically cortisol), Conn's syndrome (excess production of aldosterone or, less commonly, related salt-active steroid hormones) and the adrenogenital syndrome which takes the form of either virilism or feminization and is due to an excess of circulating androgenic or oestrogenic hormones of adrenal origin. Clinically each syndrome may either occur as a clearly distinct entity (i.e. 'in pure form') or admixed signs and symptoms may be present, as is often the case with carcinomas. The histological appearances of the hyperplastic glands are characteristic in each syndrome. Malignant adrenal tumours, on the other hand, may show a range of similar morphological features which can prevent their functional properties being deduced histologically. The benign tumours of Cushing's syndrome and hyperaldosteronism with low plasma renin (Conn's syndrome) usually do, however, present distinctive histopathological features.

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A. M. NEVILLE AND M. J. O'HARE

Cushing's syndrome Cushing's syndrome may be found at any age, although it is commonest in adults and affects females two to three times more frequently than males. If all age groups are considered, about 75% of cases are associated with bilateral adrenocortical hyperplasia (diffuse or nodular), almost all of which are associated with an elevated plasma ACTH , mainly of pituitary origin (Kreiger, 1982). The remainder are due to adrenocortical neoplasms, approximately half of which are malignant (Table 1).

Table I. The incidence of adrenal lesions in Cushing's syndrome as a function of age.' Incidence (%) Adrenal lesion Hyperplasia Adenoma Carcinoma

Adults

Children

All ages

78 13 9

42

74

12

14 12

46

'Data of Neville and O'Hare (1982).

Simple (or diffuse) hyperplasia Almost all adult adrenal glands showing simple (or diffuse) hyperplasia and which are removed at operation weigh between 6 and 12 g, are yellow-brown and have rounded contours. On section, the cortex is broadened and consists of an inner brown layer, occupying one-third to one-half of the cortex, and an outer yellow layer. In autopsy glands, this distinction is lost and the cortex is a diffuse brown colour. Not infrequently, small «0.25 ern) yellow nodules may be present. Microscopically, the inner zone corresponds to a broadened compact cell zone while the outer layer consists of clear cells (Figure 4). The zona glomerulosa usually has a normal focal distribution. These morphological appearances are those predicted in view of the increased levels of plasma ACTH in this form of hypercorticalism and its known effects on the normal gland and its functional zonation (see earlier). Two other changes may also be seen in Cushing's syndrome with hyperplasia. These arc adipose spaces in the zona reticularis and cellular hypertrophy, often with nuclear pleomorphism of both zona reticularis and zona fasciculata cells. These latter features tend to be found in glands weighing over 12 g, often, but not always, associated with overt pituitary tumours, and with ectopic sources of ACTH (when individual gland weights of more than 20 g are not uncommon), where virtually the entire cortex may consist of compact cells. They are probably the result of prolonged ACTH stimulation and/or particularly high levels of steroids within the cortex.

HISTOPATHOLOGY OF THE HUMAN ADRENAL CORTEX

799

Figure 4. Cushing's syndrome. Bilateral diffuse hyperplasia (operation specimen: 6.6 g). The cortex is broader than normal and exhibits a widened compact cell zona reticularis which forms an undulating border with the zona fasciculata (H&E; xSO).

Bilateral nodular hyperplasia Bilateral nodular hyperplasia accounts for about 20-23% of all examples of hyperplasia with Cushing's syndrome (Table 2) and denotes the presence of one or more prominent yellow nodules, visible to the naked eye, occurring in glands in which the remaining cortex is hyperplastic (Figure 5). In fundamental terms, however, we would not distinguish between simple and nodular hyperplasia, which can be best regarded as different morphological aspects of a single disease process (Neville and Symington, 1967). Both glands almost always contain nodules and often show a weight disparity, unlike simple hyperplasia. The nodules consist mainly of clear cells arranged in acini and cords contiguous with and compressing the related cortex, which shows the typical features of simple adrenocortical hyperplasia (Figure 5). Some such nodules contain foci of compact cells and/or collections of adipose cells. Cellular hypertrophy and pleomorphism may occur in some and has been interpreted as evidence of functional autonomy and possibly a preneoplastic disease state. This has not been the authors' personal experience.

800

A. M. NEVILLE AND M. J. O'HARE

Table 2. The relative incidence of different pathologies in bilateral adrenocortical hyperplasia causing Cushing's syndrome. * Adults

Children

Pathology

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Age (years)

Sex (F/M)

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Sex (F/M)

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62 20

20-40 40-50

3: I 3: I

62 23

9-15 <1

2:3 3: 1

18

40-60

I: 3

15

Any

1: I

*Data of Neville and O'Hare (1982).

Nodule morphology in nodular hyperplasia with Cushing's syndrome is therefore similar to that of the 'non-functioning' adrenal nodule (Figure 3) and the adenoma of Cushing's syndrome (see Figure 6). Clear-cut histopathological differentiation of these entities may be achieved' only by examining the attached cortex, which is of normal size with 'nonfunctioning' nodules, atrophic with cortisol-producing adenomas (see Figure 9), and always hyperplastic in nodular hyperplasia (Figure 5).

Figure 5. Cushing's syndrome. Bilateral nodular hyperplasia (operation specimen: 21 g). The gland exhibits a large multi-lobulated nodule (2.5 em in diameter) at one pole composed predominantly of clear lipid-laden cells and which compresses the related cortex. Elsewhere, the cortex exhibits the characteristic features associated with diffuse hyperplasia (see Figure 4) (H&E; xz),

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801

Bilateral micronodular hyperplasia Another form of nodular hyperplasia, associated with Cushing's syndrome, referred to as micronodular hyperplasia, has been recorded predominantly in the neonate (e.g. Donaldson et aI, 1981) and around puberty. Both situations may have a familial basis (Schweizer-Cagianut et al, 1980) and a number have been associated with lowered plasma ACTH values suggesting autonomy (Donaldson et al, 1981). In the pubertal and rare adult examples, the bilateral, multiple nodules are yellow or brown with clear or compact cells. Cellular hypertrophy and nuclear pleomorphism may be present. In the neonate, a persistent fetal zone may be noted (see Neville and O'Hare, 1982). Apart from one case (Shenoy et aI, 1984), the cortex does not appear to be atrophic in this disease, the aetiology of which is not presently known. Adrenocortical tumours Adrenocortical tumours account for about one quarter of all cases of Cushing's syndrome (Table 1). Their incidence, especially carcinomas, is higher in children, particularly girls. In adults, both adenomas and carcinomas occur more frequently in females and are particularly prevalent between the ages of 30 and 60 years (Table 1; see also Bertagna and Orth, 1981). Adenomas generally result in the 'pure' form of the syndrome. Carcinomas, on the other hand, are frequently associated with degrees of virilism and hypertension not found in hyperplasia causing Cushing's disease, in addition to the stigmata of hypercorticalism to give the so-called 'mixed' Cushing's syndrome. The benign tumours of Cushing's syndrome are usually highly characteristic lesions. They are small, round, apparently encapsulated growths, the cut surface of which is yellow with dark red or brown foci. Areas of necrosis and haemorrhage are infrequent. They occur with equal frequency in either gland, are almost always single, and generally range between 10 and 40 g in weight, although tumours of up to 250 g have been removed without subsequent evidence of malignancy. On microscopic examination, a tenuous capsule surrounds the lesion. The yellow areas correspond to lipid-laden cells, morphologically similar to the cells of the zona fasciculata of the normal adrenal cortex (Figure 6). The brown areas consist of compact cells with eosinophilic lipid-poor granular cytoplasm, and are similar to the cells of the zona reticularis of the normal adrenal cortex. The tumour cells are arranged in small cords or alveoli. Nuclear or cellular pleomorphism is uncommon, but the latter may be evident in small areas. In contrast to nodules, the cortex associated with the adenomas is invariably atrophic (see Figure 9). The rare so-called 'black adenomas', some of which have been found to cause Cushing's syndrome, consist predominantly of compact eosinophilic lipofuscin laden cells. All examples which we have examined have behaved in a benign fashion. Adrenal carcinomas with Cushing's syndrome generally weigh in excess

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A. M. NEVILLE AND M. J. O'HARE

Figure 6. Cushing's syndrome. Adrenocortical adenoma (operation specimen: 5 g). The tumour consists mainly of clear zona Iasciculata-type cells with small foci of compact zona reticularis-type cells (upper left). The cells are arranged in nests and cords. Little nuclear or cellular pleomorphism is apparent (H&E; x 170).

of 100 g when removed at surgery, although we have seen one tumour of lesser weight proved to be a carcinoma by its ability to metastasize. Carcinomas are usually encapsulated, soft in consistency, with a pink lobular cut surface in which areas of haemorrhage, necrosis, and cystic change are frequent. Capsular penetration or satellite nodules may be noted. The tumours usually consist of compact cells with eosinophilic granular lipid-poor cytoplasm, grouped in large alveoli, sheets, or trabeculae separated by a fine fibrovascular stroma (Figure 7). The cells and nuclei may be uniform in size, although the nuclei may be larger and more vesicular than normal. More commonly, particularly with the heavier lesions, the cells and nuclei exhibit pleomorphism and marked nuclear vesicularity with one or more prominent nucleoli, a feature which we have found a useful prognostic guide. However, bizarre and giant forms may be present in parts of the tumour while the remainder exhibits little nuclear atypicality (Figure 8). Extensive necrosis is often an obvious microscopic feature. Vascular invasion through the walls of blood vessels is, however, uncommon, although tumour cells may be observed within vessels. Thrombi containing tumour cells may be present in the tumour sinusoids or main adrenal vein. Mitotic figures mayor may not be seen and are not necessarily the best indicator of malignancy. Adrenocortical atrophy of the attached and contralateral gland is always present (Figure 9). Rarely it may

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Figure 7. Cushing's syndrome. Adrenocortical carcinoma (operation specimen: 170 g) Extensive nrcas of necrosis are readily apparent; viable tumour tissue is noted only in the immediate perivascular locations. Compact cells comprise the lesion; nuclear pleomorphism is readily noted (H&E; x 1(0).

be the site of metastases. Metastases are generally detected in the related lymph nodes, mediastinal nodes, bones, lungs and liver (Bennett et al, 1971). The appearances of carcinomas causing other types of hypercorticalism, as well as so-called 'non-functioning' ('non-hormonal') carcinomas, are often indistinguishable from those causing Cushing's syndrome. There is thus a wide spectrum of cellular change in tumours proved subsequently to be carcinomas by their ability to metastasize. The usual histological criteria of malignancy are frequently absent and can occur in benign lesions. A tentative diagnosis is possible if large areas of necrosis are present and if enlarged, vesicular pleomorphic nuclei with one or more prominent nucleoli are noted.

The attached and contralateral adrenal gland with tumours A histological distinction of tumours associated with hypercorticalism can, however, be made if the attached and/or contralateral adrenal is available for study. This is always small and atrophic with benign and malignant functioning adrenal tumours in Cushing's syndrome. The cortex consists of clear cells only and is surrounded by a thickened oedematous capsule (Figure 9). This is the appearance expected in view of the very low levels of peripheral plasma ACTH «10 pg/ml) resulting from the neoplastic production of cortisol. The appearance of the attached gland may,

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A. M. NEVILLE AND M. J. O'HARE

Figure 8. Cushing's syndrome. Adrenocortical carcinoma (operational specimen: 71 g). This lesion shows marked nuclear and cellular pleomorphism in one part of the lesion, emphasizing the importance of adequate tissue sampling in reaching a diagnosis of prognostic value (H&E; xl-t5).

however, be modified if the patient has been treated with adrenal suppressive drugs such as metyrapone, allowing some recovery of ACfH levels prior to surgery. In tumours not producing glucocorticoid hormones (e.g, those associated with 'pure' forms of virilism or feminization and the 'non-functioning' carcinomas), atrophy of the attached/contralateral gland is neither anticipated nor seen. Adrenogenital syndrome The adrenogenital syndrome is associated with raised levels of circulating sex hormones and/or their precursors, causing both sexual precocity and/or

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Figure 9. Tumorous Cushing's syndrome. Attached or contralateral adrenal gland. The atrophic adrenal cortex is surrounded by an ocdernatous, thickened capsule and consists solely of lipid-laden cells of the zona fasciculata-typc (H&E; x30).

heterosexual dysfunction, depending on its time of onset. The commonest adrenal change is congenital adrenocortical hyperplasia (CAH) due to various inherited defects in steroid biosynthesis (New and Levine, 1984), but the syndrome can also be caused by both benign and malignant adrenocortical tumours. About 80% of patients with this syndrome, whatever the pathology, are female. Irrespective of sex, 50% of tumours are detected before the age of 12 years, Congenital adrenocortical hyperplasia With virilism. Three enzyme defects can result in CAH with virilismpartial or complete loss of Zl-hydroxylase which accounts for about 90% of cases (Migeon, 1980), less commonly reduced lIB-hydroxylase and even more infrequently, a 3B-hydroxy-~5-steroid dehydrogenase-isomerase deficiency. All of these defects reduce effective glucocorticoid production while sparing a range of precursor steroids with androgenic potential responsible for the virilism. All the adrenal changes in congenital adrenocortical hyperplasia are explicable on the basis of the markedly increased production of ACTH, which attempts to compensate for the reduced glucocorticoid output. The average weight of a single adrenal obtained at autopsy from an affected untreated child (neonates to 12 years of age) is 15 g compared with a normal value of 1.5-3 g; in adults, they each weigh approximately 30-35 g. The glands have a highly characteristic cerebriform appearance with a

806

A. M. NEVILLE AND M. J. O'HARE

diffuse brown cut surface. Microscopically, the appearances are also characteristic, with the cortex composed predominantly of compact cells extending from the medulla to the zona glomerulosa. A small zone of clear cells with lipid-rich cytoplasm may be present, separating the compact and glomerulosa cells. As most of these enzyme defects should also involve a concomitant reduction in aldosterone biosynthesis, it is not unusual to find compensatory hyperplasia of the zona glomerulosa when a salt-losing syndrome is also present. However, since in about 70% of cases of 21-hydroxylase deficiency aldosterone biosynthesis may be spared (Bartter et aI, 1968), such changes need not be present. Increased size of the zona glomerulosa is not expected in lIB-hydroxylase defects as this defect results in increased deoxycorticosterone levels, compensating for the loss of aldosterone.

Without virilism. The congenital enzyme defects causing adrenal hyperplasia without virilism are rare (see New and Levine, 1984). That which results in defective cholesterol usage, caused by deficiencies of the C20- 22 desmolase enzyme system is associated with characteristic adrenal changes, The adrenal changes in others, such as loss of corticosterone methyl oxidase (Type I and II) with reduced aldosterone levels (Ulick, 1976), or 17-hydroxylase, remain to be described as no reported cases have come to autopsy. Due to high circulating ACTH levels in individuals with defective cholesterol usage (congenital lipoid hyperplasia), the adrenal glands are heavier than normal, individual weights of between 3 and 12 g having been reported in neonates and in children (Moragas and Ballabriga, 1969). On sectioning, the cortex is nodular and has a diffuse yellow to white colour. Microscopically, all the adrenal cells appear as clear lipid-laden cells (Figure 10). In addition, foci of cholesterol 'clefts' and associated foreign-body-type giant cells are common. Neoplasia Virilizing tumours. Unlike tumours associated with Cushing's syndrome, there is a considerable overlap in the size and weight of benign and malignant virilizing tumours. Although large tumours are again more likely to be malignant, adenomas have been known to weigh as much as 1.5 kg. All tumours are encapsulated and have a reddish-brown cut surface. With increasing size, areas of necrosis, haemorrhage, cystic change, and foci of calcification can be observed. They are more frequent in children than adults, and commoner in females than males (Benaily et aI, 1975). These tumours contain one or more enzyme deficiencies which tend to channel steroidogenesis towards production of sex hormones and/or their precursors (Neville et aI, 1969). Although testosterone synthesis as such has been recorded in some cases, most tumours produce greater amounts of other C 19-steroids and their precursors, such as DHA and/or its sulphate and androstenedione. Unfortunately, the pattern of steroid output gives little, if any, indication of the lesion's malignant potential.

807

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Figure 10. Congenital adrenocortical hyperplasia (congcnitallipoid hyperplasia). The cortex consists almost exclusively of lipid-laden clear cells. Numerous cholesterol clefts and related foreign body giant cell reactions are noted in this condition associated with defective cholesterol utilization (H&E; xSO).

Compact cells generally are the sole cell type in these growths. In adenomas the cells, which are arranged in short cords or acini, have single, uniform, vesicular nuclei and may be of normal size (Figure 11), Individual cells may show necrosis. As tumours increase in weight, the component cells and their nuclei enlarge and exhibit increasing nuclear and cellular pleomorphism (Figure 12). The histological classification of such tumours as benign or malignant is extremely difficult. In proved carcinomas, the compact cells may have a syncytial arrangement or they form large alveoli with prominent vascular sinusoids. In addition, there may be large areas of necrosis, and vesicular, pleomorphic and/or enlarged nuclei with prominent nucleoli are usually found. Bizarre and giant forms may occur; mitoses, however, are seldom prominent. The appearances are, thus, similar to the carcinomas causing Cushing's syndrome (Figures 7 and 8).

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Figure II. Adrenogenital syndrome. Virilizing adrenocortical adenoma (operation specimen: 25 g). The tumour consists of compact cells arranged in short cords separated by prominent vascular spaces. The cells arc normal in size and exhibit little pleomorphism (H&E; x260).

Figure 12. Adrenogenital syndrome. Virilizing adrenocortical adenoma (operation specimen: 228 g). The tumour consists of compact cells which arc larger than normal and exhibit prominent nuclear pleomorphism. Prominent nucleoli and nuclear vesicularity arc not features of this lesion (H&E; x 180).

HISTOPATHOLOGY OF TilE HUMAN ADRENAL CORTEX

809

Feminizing tumours. Feminizing carcinomas (Gabrilove et aI, 1965) are the rarest form of cortical tumour next to carcinomas causing hyperaldosteronism. Most are diagnosed in men of age 20 to 50 years. Tumours vary in weight from 10 g to more than 2 kg. In our experience, their gross and histological features are indistinguishable from virilizing or large cortisolsecreting tumours. Of the tumours diagnosed as adenomas, few have been followed long enough to substantiate this diagnosis. Long periods of reappraisal are necessary, as the development of metastases can be delayed for up to eight years. Consequently, all feminizing tumours should be treated as carcinomas, irrespective of 'histology. In functional terms, the differences between tumours causing virilism in females and feminization in males are minimal. In one case an adrenal carcinoma which caused virilism in a child as its primary presenting symptom, recurred with feminization after treatment (Halmi and Lascari, 1971). As with virilizing tumours, the steroid secretion patterns of feminizing tumours are suggestive of various enzyme defects, which tend to channel steroidogenesis towards sex steroid formation. Oestrogen excretion rates rise to adult female levels, or above (Gabrilove et aI, 1970). Cwsteroids are also elevated in most patients, with DHA accounting for up to 50% of the total urinary 17-ketosteroids. Occasional tumours of this type also produce cortisol and may be associated with Cushing's syndrome as well as feminization. The distinction of benign from malignant adrenocortical tumours As the above descriptions indicate, there are few, if any, absolute prognostic criteria for certain types of adrenocortical tumour, apart from the overt presence of metastases. While a microscopic scoring system can be helpful (Weiss, 1984), we believe that a combination of morphological and functional criteria represents the best possible present approach. The greatest difficulty is encountered with compact cell tumours between 100 and 500 g in weight. In our experience, prominent nuclear pleomorphism, a high nuclear/cytoplasmic ratio, and enlarged vesicular nuclei with one or more prominent nucleoli are the criteria of most value, together with distinct areas of necrosis as opposed to single cell apoptosis. The presence of true vascular wall invasion as opposed to tumour cells in blood vessels is also helpful but rarely observed. Electron microscopic criteria as suggested by MacKay (1969) and Mitschke et al (1973) have proved disappointing due largely to sampling problems, and correlations between ultrastructure and function are not generally apparent (Silva et ai, 1982). Studies of tumours in culture (O'Hare et aI, 1979; Neville and O'Hare, 1982) have shown that all the lesions subsequently proved to be malignant by their ability to metastasize have possessed various functional abnormalities not seen with benign lesions. Abnormal responses to ACTH, cyclic AMP and/or the predominant production of precursor type steroids (such as ll-deoxycortisol) instead of cortisol and corticosterone were noted in all

810

A. M. NEVILLE AND M. J. O'HARE

malignant lesions, although no single abnormality was pathognomonic. Some of these steroid biosynthetic abnormalities are reflected in plasma and urinary steroid profiles (Lipsett and Wilson, 1962), and abnormalities have also been described in short-term in vitro studies (Saez et al, 1975). Such functional tests, if available, should aid prognostication in difficult cases. Hyperaldosteronism with low plasma renin (Conn's syndrome) This syndrome (Conn, 1955; Conn et ai, 1964) is associated with three types of adrenal change: tumour, nodules and hyperplasia of the zona glomerulosa, which may occur singly or in combination (Table 3). Approximately 65% of patients with this disorder have adrenal tumours, which occur more often in females than in males (in a ratio of 3: 1) and usually occur in individuals between 30 and 50 years of age. The syndrome rarely afflicts children. Non-tumorous hyperaldosteronism accounts for the remainder and tends to affect older persons, occurring with an approximately equal frequency in both sexes.

Table 3. Classification of adrenal changes in hyperaldosteronism with low plasma renin based upon 153 personally studied cases.' Group

Histological subdivisions

Adrenocortical tumour

Adrenal adenoma with hyperplasia of zona glomerulosa Adrenal adenoma with hyperplasia of zona glomerulosa and with nodules Adrenal carcinomat

No adrenocortical tumour

Hyperplasia of zona glomerulosa Hyperplasia of zona glorncrulosa with micronodules Hyperplasia of zona glomerulosa with micronodules and macro nodules Normal zona glomerulosa with micronodules

Incidence

::}

I~: }

82%

18%

'Some of the cases have been reported previously and summarized by Neville and O'Hare (1982). fAttacbed and/or contralateral gland was not available for study in the examples personally studied.

Non-tumorous hyperaldosteronism with low plasma renin This tends to occur in patients between 40 and 60 years. It accounts for about 15-35% of all cases of hyperaldosteronism with low plasma renin, but is now rarely seen by the pathologist because of improved diagnostic criteria enabling its distinction from tumorous hyperaldosteronism (Ferriss et aI, 1970). The pathological features vary, possibly implying multiple aetiologies.

HISTOPATHOLOGY OF THE HUMAN ADRENAL CORTEX

811

The appearances of the glands are variable-some are normal, others weigh less than normal and yet others are larger and heavier than normal. Nodules of varying size are frequent, possibly due to hypertension. In general, the microscopic appearances are similar to those described below for glands associated with tumours, i.e. hyperplasia of the zona glomerulosa with or without nodules, both of macroscopic and microscopic size. Glomerulosa hyperplasia with micronodules is the most frequent finding. The precise changes can vary from one part of the gland to another so that multiple sections are needed to reach an accurate tissue diagnosis. Similar appearances may be seen bilaterally in patients with secondary hyperaldosteronism and in patients with non-tumorous hypertension and low plasma renin associated with the hypersecretion of DOC (Brown et aI, 1972).

Neoplasia Almost all adrenal tumours causing hyperaldosteronism are benign. Ninety-two per cent are unilateral and single, and they occur more frequently in the left adrenal. When multiple (8%), they are still usually unilateral. Many measure less than 2 em in diameter and 58% weigh less than 4 g. Nevertheless, a few adenomas can weigh as much as 75 g when they overlap with the weights of carcinomas associated with hyperaldosteronism. The typical small adenoma associated with this syndrome is a circumscribed, encapsulated lesion with a distinctive golden-yellow cut surface. Such tumours may project from one pole of the gland or be wholly intraglandular. With increasing size, areas of necrosis, haemorrhage and cystic change may occur. Carcinomas, on the other hand, present gross appearances indistinguishable from those causing other forms of hypercorticalism. With adenomas, the attached gland usually shows some atrophy of the inner zones and is reduced in weight. Adenomas have a characteristic histological appearance typified by their protean cellular morphology. Four cell types occur in such lesions: large and small clear, lipid-laden cells, zona glomerulosa-type cells and zona reticularis-type (compact) cells (Figure 13). Very few adenomas consist of a single cell type; indeed, all four types may be found in one tumour. The commonest pattern consists of large, lipid-laden clear cells similar to those of the normal zona fasciculata in size and nuclear/cytoplasmic ratio; they are arranged in small cords or alveoli separated by fine, fibrovascular connective tissue. The nuclei are vesicular, often with inclusions, and pleomorphism mayor may not be seen. Such cells may occur alone but are more commonly found in association with smaller lipid-rich cells which possess a vesicular nucleus and a nuclear/cytoplasmic ratio similar to that of a zona glomerulosa cell. This cell type, referred to as an intermediate (hybrid) cell, seems to have the cytological characteristics of both zona glomerulosa and zona fasciculata cells. In many tumours, zona glomerulosa-type cells are also present. Rarely, they may be the sale component. Generally, such cells are seen in nests or short cords around the periphery of the lesion dipping in a tongue-like

812

A. M. NEVILLE AND M . J. O'HARE

Figure 13. Hyperaldosteronism with low plasma renin . Adrenocortical adenoma (operation specimen: 3.9 g). The tumour displays all four cell types which may be found in this disorder, with clear cells (left), intermediate cells (below), zona glornerulosa-type cells (above) and zona reticularis-type cells (upper right) (H&E; x 150).

manner into the body of the tumour accompanied by fibrovascular trabeculae (Figure 14). Groups of compact cells are occasionally noted in association with the other cell types, and in a rare case, hyperaldosteronism has even been associated with a 'black' adenoma (Caplan and Virata, 1974). Spironolactone bodies may be noted in the tumours of patients given this drug preoperatively (Conn and Hinerman, 1977). This cellular heterogeneity and occasional foci of nuclear pleomorphism should not mislead one into a diagnosis of malignancy, as these appearances arc entirely characteristic of benign lesions causing Conn's syndrome. Proved carcinomas associated with hyperaldosteronism are rare; only about 30 have been reliably documented (see Neville and O'Hare, 1982). Most are large, weighing more than 500 g although lesions between 30 g and 100 g have subsequently metastasized. Characteristically, the cells are zona glomerulosa in type or are similar to the intermediate (hybrid) cell type found in adenomas. In several of the cases which we have examined, they have been arranged in large alveoli or trabeculae separated by prominent vascular sinusoids (Figure 15). Central necrosis may be marked, and pleomorphism, mitotic activity, and haemorrhage mayor may not be present. Some areas may present a remarkably uniform appearance. Other areas of such carcinomas may, however, be indistinguishable from carcinomas associated with other forms of hypercorticalism. Carcinomas

813

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Figure 14. Hyperaldosteronism with low plasma renin, Adrenocortical adenoma (operation specimen: 1.9 g). The main bulk of the lesion consists of cells of the large clear type, Tongues of zona glomerulosa-type cells project into the tumour together with accompanying fibrovascular trabeculae. Intermediate cells are present between these two cell types (H&E; x75).

causing this syndrome pursue a most aggressive course with survival mostly being a matter of months. Excess deoxycorticosterone and corticosterone production may also cause hypertensive syndromes. These steroids are formed by the inner zone cells of the normal cortex. Tumours secreting them are, therefore, probably not of glomerulosa origin but are akin to those associated with Cushing's syndrome and the adrenogenital syndromes, and may show typical compact cell carcinoma-like appearances.

The attached and contralateral adrenal gland ill tumorous primary aldosteronism The adrenal gland attached or contralateral to benign aldosteroneproducing tumours often contains typical clear-cell nodules, probably caused by the hypertension, These range from microscopic micronodules to so-called macro nodules, 2-3 em in diameter. Most are multiple and generally bilateral, although some macronodules may be single and unilateral simulating a 'tumour'. In these cases very careful examination of the histology of the gland (Figures 13, 14) should resolve the question, failing which an investigation of its steroidogenic potential in vitro should clinch the matter.

814

A. M. NEVILLE AND M. J. O'HARE

Figure 15. Hyperaldosteronism with low plasma renin. Adrenocortical carcinoma (operation specimen: 2000 g). The carcinoma consists of large trabeculae of zona glomerulosa-type cells punctuated by prominent vascular spaces (H&E; x 120).

Paradoxically, the attached gland in most cases of tumorous hyperaldosteronism shows apparent hyperplasia of the zona glomerulosa. Most frequently it is present around the entire periphery of the cortex and is increased in width. In focal areas, tongue-like projections may extend into the cortex when they are often associated with a prominent capillary supply. In most instances the remainder of the adrenal cortex of the gland appears thinner than normal.

Interpretation of the structural and functional properties of tumours ill Conn's syndrome The morphology of Conn's syndrome tumours appears at first glance to be an enigma-composed of zona fasciculata-type cells in the main and yet associated with increased aldosterone production. There is no doubt about the tumour being the main source of the raised aldosterone levels (Kaplan, 1967). Many benign tumours, however, have few recognizable zona glomerulosa-type cells, which are usually found in relation to the capsule or fibrovascular trabeculae permeating the tumour. Cortisol and corticosterone are, in fact, present in much greater amounts within such tumours (Kaplan, 1967; Neville and O'Hare, 1982).

IIISTOPATHOLOGY OF TIlE HUMAN ADRENAL CORTEX

815

Culture studies have shown that normal zona glomerulosa cells which initially produce aldosterone can rapidly modulate to secrete only glucocorticoids (Hornsby et al, 1974; Hornsby and O'Hare, 1977). Ultrastructurally, there is also a morphological transition to cells of the zona fasciculata-type in vitro. Benign aldosterone-producing tumours, irrespective of morphology, behave functionally in a similar manner when introduced into culture, i.e. aldosterone production is not sustained with a greater release of cortisol (Neville and O'Hare, 1982). The glomerulosa phenotype is clearly labile and this lability is also found in the adenomas. If the normal processes of functional zonation (see Hornsby, 1985) controlled by local factors persist in the benign tumours, albeit in a morphologically disorganized fashion, then their morphology can be interpreted as follows. A continuing process of modulation of glomerulosa phenotype to inner zone functions is probably occurring throughout the tumour, leading ultimately to cortisol and corticosteronesecreting fasciculata-type cells. The intermediate cells seen in the lesions may be truly functional and structural transition forms between the two cell types. This explanation of the cellular heterogeneity of such tumours raises the intriguing, but probably unprovable, possibility that some non-functioning nodules associated with hypertension may have been 'Conn's adenomas' to start with, causing established essential hypertension but eventually converting entirely to zona fasciculata-type cells. 'Non-hormonal' adrenocortical tumours Adrenocortical tumours are considered 'non-hormonal' if there is no evidence of endocrine imbalance. Such tumours are not necessarily steroidogenically inert; rather, they fail to form biologically active hormones. They may form inactive precursor steroids and/or their metabolites, e.g. pregnenolone (Fukushima and Gallagher, 1963; Fantl et aI, 1973). Approximately 200 examples have been recorded in the literature, usually being diagnosed during the fifth to seventh decades of life, although children are not exempt. They occur in males twice as often as females (Lewinski et al, 1974) and should not be confused with adrenal nodules. These tumours have gross features similar to those of functioning adrenocortical carcinomas (see Figures 7, 8) although they tend to be larger, probably because they fail to produce clinical signs and symptoms of hormonal excess at an early stage. Weights in excess of 1 kg are common. Microscopically, the predominant cell is of the compact type, although occasional tumours contain more clear than compact cells, possibly because of the defective utilization of cholesterol (compare with congenital lipoid hyperplasia, above). The prognosis is poor with malignant non-hormonal cortical tumours as with other adrenal carcinomas. Most patients die within one year of diagnosis.

816

A. M. NEVILLE AND M. J. O'HARE

In the follow-up of patients with carcinomas without overt function, it is essential to characterize the nature of the precursors being released (see above), if possible, and to use these as index substances to monitor the clinical course of the patient.

HYPOCORTICALISM Acute acquired adrenoprivic hypocorticalism Acute acquired adrcnoprivic hypocorticalism was once thought to be most often due to bilateral adrenal haemorrhage (e.g. Waterhouse-Friderichsen syndrome). However, Migeon et al (1967) have shown that bilateral haemorrhage is seldom, if ever, associated with acute adrenal insufficiency. Plasma cortisol levels are, in fact, elevated in response to this stress. The commonest cause of acute adrenal insufficiency is therefore probably sudden withdrawal of replacement steroids in subjects with Addison's disease or following bilateral adrenalectomy. Chronic acquired adrenoprivic hypocorticalism All patients with chronic acquired adrenoprivic hypocorticalism present with Addison's disease. Of the possible causes, organ specific autoimmune adrenalitis (OSAA) associated with certain HLA types (see New et aI, 1981) is the commonest (Nerup, 1974; Irvine and Barnes, 1975). In OSAA, the adrenal glands are small and may even only be identified by microscopy of the suprarenal bed. The atrophy is diffuse involving the entire cortex. Only isolated clusters of cells may remain and, in extreme cases, none remain at all (Figure 16). Such cells as remain are compact in type (i.e, ACTH-stimulated) and there is often diffuse lymphocytic infiltration with plasma cells and macrophages in relation to the cortical cells as a consequence of the autoimmune process. Both cell surface-directed (Khoury et aI, 1981), cytoplasmic componentreacting and precipitating autoantibodies have been described in such cases and may be related both to the genesis of atrophy and in part be a consequence thereof. This form of Addison's disease occurs not infrequently in conjunction with other autoimmune syndromes (Schmidt's syndrome, hypoparathyroidism). Another form of chronic adrenal insufficiency occurs in conjunction with diffuse demyelinating disorders (Addison-Schilder's disease). This is a familial lipid-storage disease (Schaumberg et aI, 1975). It is associated with a characteristic adrenal cellular hypertrophy and cytoplasmic striations caused by lipid deposits (Powers et al, 1980). Metastatic carcinoma involving the adrenal is generally regarded as a rare cause of Addison's disease despite the not infrequent involvement of the gland by secondary neoplastic foci. However, a recent study employing cr scanning to detect adrenal involvement together with steroid bio-

817

HISTOPATHOLOGY OF TilE IIUMAN ADRENAL CORTEX

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Figure 16. Idiopathic Addison's disease. This atrophic gland contains only small islands of surviving compact adrenocortical cells between which a chronic inflammatory infiltrate may be seen (H&E; x 160).

chemical studies suggest that although symptomatic Addison's disease may be rare, some degree of adrenal insufficiency was noted in 19% of the patients studied who had adrenal involvement (Seidenwurm et aI, 1984). The pathological features of the other rarer causes of Addison's disease discussed in chapter 8 have been described in detail elsewhere (Neville and O'Hare, 1982). There is little that is unusual in their adrenocortical manifestations where these have been observed, or for that matter in tropoprivic hypocorticalism where the gland is deprived of ACTH by disease processes involving the pituitary (e.g. Sheehan's syndrome, Simmonds' disease or by iatrogenic effects) when the atrophic gland consists almost entirely of clear cells (see Figure 9). Congenital and familial forms of hypocorticalism with cortical hypoplasia have also been documented (e.g. Hay et aI, 1981) although these are rare. Their histological appearances, which include cytomegalic fetal adrenal-like cells in some cases, have been illustrated in a recent review (Neville and O'Hare, 1982).

818

A. M. NEVILLE AND M. J. O'HARE

SUMMARY The morphological features of the adult human adrenal cortex are described with particular respect to changes induced by alterations in function of the hypothalamo-pituitary axis. The occurrence of nodules in the normal and hyperplastic cortex (Cushing's and Conn's syndromes) is discussed in relation to the diagnostic problems that they still pose. Explanations based on the normal mechanisms of functional zonation in the cortex are provided for the different cell types which comprise cortical neoplasms associated with various syndromes of hypercorticalism (Cushing's, adrenogenital and Conn's syndromes), together with morphological and functional criteria to distinguish adenomas from carcinomas. REFERENCES Bartter FC, Henkin RI & Bryan GT (1968) Aldosterone hypersecretion in 'non-salt-losing' congenital adrenal hyperplasia. Journal of Clinical Investigation 47: 1742. Benaily M, Schweisguth 0 & lob JC (1975) Les tumeurs corticosurrenales de I'enfant. Etude retrospective de 34 cas observes de 1954 a 1973. Archives Francaises de Pediatric 32: 4·H. Bennett AH, Harrison JH & Thorn GW (1971) Neoplasms of the adrenal gland. Journal of Urology 106: 607. Bertagna C & Orth N (1981) Clinical and laboratory findings and the results of therapy in 58 patients with adrenocortical tumors admitted to a single medical center (1951-1978). American Journal of Medicine 71: 855. Brown JJ, Ferriss JB, Fraser R et ai, (1972) Apparently isolated excess deoxycorticosterone in hypertension. A variant of the mineralocorticoid-excess syndrome. Lancet ii: 243. Caplan RH & Virata RL (1974) Functional black adenoma of the adrenal cortex. A rare cause of primary aldosteronism. American Journal of Clinical Pathology 62: 97. Conn JW (1955) Presidential address. Part I: painting the background. Part II: primary aldosteronism: a new clinical syndrome. Journal of Laboratory and Clinical Medicine 45:

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O'Hare MJ, Monaghan P & Neville AM (1979) The pathology of adrenocortical neoplasia: a correlated structural and functional approach to the diagnosis of malignancy. Human Pathology 10: 137. O'Hare M1, Nice EC & Neville AM (1980) The regulation of androgen secretion and sulfoconjugation in the adult human adrenal cortex: studies with primary monolayer cultured cells. In Genazzani AR, Thijssen 1HH & Siiteri PK (eds) Adrenal Androgens, pp 7-25. New York: Raven Press. Powers JM, Schaumburg HH, Johnson AB & Raine CS (1980) A correlative study of the adrenal cortex in adenoleukodystrophy. Evidence for a fatal intoxication with very long chain fatty acids. Enzyme histochemistry, fine structure, tissue culture, proposed molecular model and cellular pathogenesis. Investigative and Cell Pathology 3: 353. Prinz RA, Brooks MH, Churchill R et al (1982) Incidental asymptomatic adrenal masses detected by computed tomographic scanning. Is operation required? Journal of the American Medical Association 2~: 701. Russell RP, Masi AT & Richter ED (1972) Adrenal cortical adenomas and hypertension. Medicine 51: 211. Saez 1M, Dazord A & Gallet D (1975) ACTH and prostaglandin receptors in human adrenocortical tumors. Apparent modification of a specific component of the ACTHbinding site. Journal of Clinical Investigation 56: 536. Schaumburg BB, Powers JM, Raine CS, Suzuki K & Richardson EP (1975) Adrcnolcukodystrophy. A clinical and pathological study of 17 cases. Archil'es of Neurology 32: 577. Schweizcr-Cagianut M, Froesch ER & Hedinger C (1980) Familial Cushing's syndrome with primary adrenocortical microadcnornatosis (primary adrenocortical nodular dysplasia). Acta Endocrinologica 9..: 529. Seidenwurm DJ, Elmer EB, Kaplan LM et al (1984) Metastases to the adrenal glands and the development of Addison's disease. Cancer 5..: 552. Shenoy BV, Carpenter PC & Carney JA (1984) Bilateral primary pigmented nodular adrenocortical disease. American Journal of Surgical Pathology 8: 335. Silva EG, Mackay B, Samaan NA & Hickey RC (1982) Adrenocortical carcinomas: an ultrastructural study of 22 cases. Ultrastructural Pathology 3: 1. Symington T (1969) Functional Pathology ofthe Human Adrenal Gland, p 3-216. Edinburgh: Livingstone. Tannenbaum M (1973) Ultrastructural pathology of the adrenal cortex. In Sommers SC (ed) Pathology Annual, Vol. 8, p 109. New York: Appleton-Century-Crofts. Ulick S (1976) Diagnosis and nomenclature of the disorders of the terminal portion of the aldosterone biosynthetic pathway. Journal of Clinical Endocrinology and Metabolism 43: 92. Weiss LM (1984) Comparative histologic study of 43 metastasizing and nonmetastasizing adrenocortical tumors. American Journal of Surgical Pathology 3: 163-169.