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Intradermal nevus associated with epidermoid cyst in the mucous membrane of the cheek
Intradermal nevus associatedwith epidermoid cyst in the mucous membrane of the cheek Jorge Gutmann, D.D.S., * Carlos Cifuentes,D.D.S., * Pedro Gandulfo, D.D.S., ** and Federico Guesalaga, D.D.S., ** Valparaiso, Chile A case of epidermoid cyst associated with an unusual amelanotic intradermal nevus, with structures identical to Meissner’s tactile corpuscles, is reported. The possible relationship and the origin of both lesions are discussed.
T he term nevus was originally
used to designate any well-circumscribed congenital discoloration of the skin or mucosa,flat or elevated, of vascular or nonvascular origin.‘, 2, 11,I23l*, l5 The tendency today is to restrict the use of the term to lesions of the skin and mucosal comprising cells-with a melanin-producing potential29 11,12,l4 These “cellular,” “melanocytic,” or “pigmented” nevi are sometimespresentat birth, but more often they arise during puberty or early adulthood.i-3, 5-g*11-13,15-1*These lesions are thought to representdevelopmental tumorlike malformations and are thus usually consideredamong he
ha~omas.6,
9, 11, 12, 15
Nevi occur infrequently on the oral mucosabut have been reported on the lower lip, and Walgingiva, palate, upper lip, tongue and cheek.1, 2, 5, 6, 9, 11. 12, 15-17 Weathers dron,17in 1965, addedten new casesof oral nevus to a review of sixteen acceptablecases. King and associates5reported five casesin 1967. WeatherP addedsix additional casesin 1969. Isolated caseshave been reported by a variety of authors.4Oral nevi are usually of the intradermal type.2, 4, 5*9*15-17 The intradermal nevus shows a characteristic microscopic appearance.” In the upper cutis the nevus cells form groups or nests of epithelioid cells, well defined by a fibrillar connective tissue border.7, l1 Subjacent to these cell nests, the nevus cells form more cordlike structures. The deep margins may show cells which are richer in cytoplasm and have less distinct cell outlines, forming syneytial masseswhich diffusely infiltrate the surrounding stromal tissue.6Thus, the nevus cell usually shows an epithelioid form in the more superhcial aspect of the lesions, whereas in the deeper margins it may assumea histiocytic, fibmblastic, or Schwann cell form.7, 14*l5 In the histologic description of intradermal nevus, frequent mention is made of struc*Department of Pathology, University of Chile. **Division of Oral Surgery, “Ahnirante Nef” Naval Hospital.
76
Volume 45 Number 1
lntradermal nevus associated with epidermoid cyst
77
tures which have a certain resemblance to neural structures, such as nerve endings or neurofibroma. These structures have been variously termed nevus corpuscles, lames foliacees, and neurofibromatoid and meissneroid structures and have been variably described and interpreted. 6* ‘9 l* Some authors believe that these structures represent a concentric arrangement of collagen around nevus cells; others believe that they represent a differentiation of the cytoplasm of the syncytial masses.6* ’ WilliP suggests that the meissneroid corpuscles arc formed by a partial fibrosis of nevus cell cords. A description by Rotter and Lapp” suggests that the nevus cells themselves form structures that resemble Meissner’s corpuscles. There is no concensus on the histogenesis of the cells which give rise to the common mole.’ Some authors support an exclusive epidermal origin in which the nevus cell is simply a modified basal cell which detaches from the epidermis and migrates into the dermis (Unna’s Abtropfungstheorie). In keeping with this concept, the nevus type (junctional, intradermal, compound) is dependent on age .’ Other authors support the theory advanced by Masson, in 1926, that melanocytes, as well as nevus cells, have a neural origin.7 In 1951 Massona suggested that nevus cells could originate from melanoblasts of the epidermis and from Schwann cells of the dermal nerves. According to this theory, junctional nevi would have their origin from melanoblasts of the epidermis only, whereas compound and intradermal nevi could have a dual origin from melanoblasts and Schwann cells. Further suggested possibilities are that the nevus cells may arise from the endoperineurium or specialized nerve endings similar to the Merkel-Ranvier corpuscles.” l1 Thoma,13 in reviewing Masson’s theory on the neural origin of nevus cells, suggests that the pigmented nevus is the result of proliferation of the entire terminal apparatus of the sensory nerves of the skin, especially of Meissner’s corpuscles. CASE REPORT A 4%year-old white man visited the Naval Hospital Oral Surgery Service, Valparaiso, with a painful swelling in the right buccal mucosa. He reported that a well-defined nodule had been present for more than one year and had developed after he accidentally bit his cheek. He stated that the tumor had undergone periodic recession but generally continued to enlarge. Recently the entire buccal mucosa had become suddenly swollen and painful. Clinical examination revealed a swelling which extended from the right comer of the mouth to the third molar area. The lesion was painful to pressure. Oral antibiotics and an enzyme were prescribed. Eventually a puslike material was discharged onto the mucosal surface. Following healing, a well-defined, spheroid, dome-shaped nodule, measuring about 15 mm. in diameter and situated on the occlusal line 1 cm. distal to the commissure, remained on the buccal mucosa. The mucosa covering the proximal half of the nodule was slightly irregular but showed normal coloration. A well-encapsulated, oval, bluish lesion and the covering mucosa were removed surgically as separate specimens and sent to the Department of Pathology with the clinical diagnosis of retention cyst and overlying hyperplastic mucosa. There has been no recurrence during the 5 years that have elapsed since surgical excision of the lesion on March 9, 1972. Pathologic
findings
Two formalin-fixed soft-tissue specimens were received for pathologic examination. One piece was a smooth-surfaced oval nodule, light brown in color and measuring 10 by 8 by 5 mm. The cut surface showed a central cavity filled with a white, cheesy material. The cyst wall was thin, with a smooth, pale inner surface. The second specimen was a flat piece of tissue measuring 5 by 5 by 3 mm., firm in consistency and pale in color. The epithelial surface appeared slightly verrucous.
78 Gutmann et al.
Oral Surg. January, 1978
Fig. 1. Cords of epithelioidcells in the wall of the epidermoidcyst. Histologically, the luminal surface of the cyst was lined with a thin squamousepithelium. The cyst cavity was filled with an amorphousgranular material containing somecholesterol slits. In the fibrous tissue portion of the cyst wall was an areashowing groups of elongatedepithelioid cells with dark-staining nuclei, arrangedin cords(Fig. 1). These structuresextendedto the margin of the tissue sections. Tissue sections prepared from the second specimen showed a slightly thickened surface epithelium generally characteristic of buccal mucosa. Some of the epithelial cells were large, vacuolated cells. In the subjacentlamina propria, and separatedfrom the epithelium by a band of connective tissue, were numerous cells showing a moderately variable orientation and configumtion. Some of the cells were large cuboidal cells with clear cytoplasm and a large, oval, moderately chromatic central nucleus. These cells formed nests (Fig. 2) in the superficial lamina propria and took on cordlike arrangementsin the submucosa.In addition to theseusual structuresof the cell nests,somecell groups tendedto form more distinct alveolar structures,while othersformed large rosettelike structures with nuclei forming “Olympic-ring” configurations (Fig. 4). Scattered throughout the tumor were elliptical structurescomposedof two cell types stackedperpendicularto the long axis of the structure. The predominant cell was a roughly “pear-shaped” clear cell with the nucleus situated in the thicker end of the cell and lying toward the periphery of the structure. Interspersedbetween these cells were thin cells containing elongated, darkly staining nuclei. The structurethus formed showedthe morphologic characteristicsof Meissner’s corpuscles(Fig. 3). Numerous small nerve fibers could be identified in the vicinity of the various nevus cell structures and occasionally forming part of thesestructures.At one side a rete ridge extendeddeeperinto the connective tissue, with the terminal cells showing changes suggestive of junctional nevus activity. Also presentin thesetissue sections were a number of microcysts, somein the earIy stages of development. Someof the cyst cavities were filled with eosinophilic, fine, granular, amorphous material; others contained keratin, and still others containedcalcified material, asdeterminedby von Kossa stain. Finally, two large group of sebaceouscells, with an associated diffuse mononuclear cell inflammatory infiltrate, were observedin the superficial submucosa.Special stainsgave no evidence of the presenceof melanin in any of the sections examined. The histologic diagnosis was epidermoid cyst of the mucous membraneof the cheekassociated with nevus of the intradermal type. DiSCUSSiON
Reports by Weathers and Waldron,” King and associates,5 Weathers16 and others indicate that, although the incidence of intraoral nevus is not high, the lesion is certainly
Volume 45 Number 1
Intradermal nevus associated with epidermoid cyst
Fig. 2. To the left of the striated muscle fiber are nests of news cells forming a structure suggestive
79
of a tactile
corpuscle.
Fig. 3. Groups of nevus cells forming
Meissner
corpuscle-like
structures.
more common than is suggested by the number of reported cases. More than one third of reported cases are nonpigmented. This feature, together with the variable clinical morphology of intraoral nevi, makes it probable that many are clinically diagnosed as papillomas, fibromas, or verrucae and are not submitted for histologic examination following excision. In the present case only the recognition of unusual cell clusters in the cyst wall prompted us to examine the fragment of overlying mucosa which was reported clinically as hyperplastic in appearance. Of particular interest in the present case are those structures within the nevus which are morphologically identical to Meissner’s corpuscles. In the literature frequent mention is made of the “neural” structures which form an integral part of the nevus. The interpretation of these structures, however, is not uniform. Masson,* in his article entitled “Mvi Conception of Cellular Nevi,” states that various authors have misunderstood and misinterpreted the structures which he referred to in a 1926 publication as foliated lamina or nevic corpuscles. References to “neutrofibromatoid” and “meissneroid” structures
80 Gutmunn et al.
Oral Surg. January, 1978
Fig. 4. Toward the left and right margins, center, are rosettes of nevus cells with overlapping nuclei forming “Olympic-ring” configurations.
would suggest a nonprecise interpretation of the structures very carefully defined by Masson. The result is that different authors use different terms to describe similar structures or apply the sameterms to dissimilar structures. Lever,’ for example, statesthat the fibrous stroma in the deep aspectsof an intradermal nevus may show structural characteristics similar to those of neurofibroma, with nevus cells arranged in narrow columns suggestive of neural sheets(neuroid tubes of Masson). “In other areasthe fibrous tissue may be in concentric arrangement (lames foliactes of Masson), resulting in structures resembling Meissner’s tactile bodies.” Willis’* statesthat neurofibromatoid changesseen in some moles are merely an incidental part without special histogenic significance. He believes that Masson’s “meissneroid” structuresare the result of partial fibrosis in groups of cells and are not differentiating supernumerarysensory corpuscles. According to Masson, the presence of these Wagner-Meissner-like corpuscles is a constant finding in adult intradermal nevi. The older and more prominent the nevus, the more frequently thesetransformations occur. Masson further statesthat “every nucleated region of the nevic simplasm is capableof undergoing a specialized development comparable to that characterizing the tactile corpusclesof Wagner-Meissner. This evolution has two extreme forms or stages;one simple, the foliated lamina, the other complex, the nevic corpuscle.” The nevic corpuscle resemblesa Wagner-Meissnercorpuscle; “however the thickened spiral ending, which characterizesthe latter, is absent.” Furthermore, at several places the periphery of the meissnemid corpuscle is continuous with the nevic simplasm from which it springs, whereasthe normal Meissner corpuscleis ordinarily in contact with the schwannian syncytium at the point where there is a small number of myelinated fibers that furnish its terminal expansion. In the presentcase, we were able to observethe continuity of the nevic corpuscle with Masson’s “nevic simplasm.” Furthermore, a thickened spiral ending made up of clear cells with a flattened pear-shapedmorphology stackedin a transverserelationship to the long axis of the corpuscle, with the thickened end oriented toward the periphery, was observedin thesestructures. Theseclear cells were interspersedwith thin cells with darkly staining nuclei, giving the structure all of the morphologic characteristicsof supemumerary Wagner-Meissner corpuscles.
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Intradermal nevus associated with epidermoid cyst
81
The presence of normal Wagner-Meissner corpuscles in rare cases of compound nevus of the fingertips and toes has been described by Masson. He states that in these areas the corpuscles may be included in the migratory zone of the melanoblasts, do not undergo any modification, and take no part in construction of the nevus. In the present case the continuity of the corpuscle with the nevic simplasm suggests that the corpuscles are derived from the formed part of the lesion. Furthermore, the location of the present lesion in the buccal mucosa supports Masson’s view that the supernumerary Meissner corpuscle formation may occur in tissues where these corpuscles are not normally present. As stated by Masson, “It would seem as if the Meissnerian potential was imparted to all cutaneous nerves but only manifested in the pathologic state in regions in which it had not been primarily exhausted by the production of normal corpuscles. ” Further features of interest in the present case were the relationship of the nevus to the epidermoid cyst and its intraoral location. Several microcysts with variable cyst contents were present between the epithelium and the superficial margin of the nevus. In one area a surface invagination of the epithelium appeared to represent an early stage of cyst formation. This feature has been described in relation to skin nevi by Thoma,13 who states that “the surface of the nevus can be covered by hyperkeratotic epithelium in which there are fissures and spaces similar to cysts.” It is apparent that this phenomenon may also occur in the oral mucosa. Whether these microcysts are in any way part of the nevus or simply represent a secondary reaction on the part of the epithelium remains an open question. Whatever the causal relationship, we believe that the cyst making up the major portion of the present case originated independent of the associated nevus. This view is based on the recognition that both epithelial rests and tumorlike malformations (hamartomas) are particularly common in embryonic lines of fusion, such as the occlusal line. In conclusion, we agree with Weathers that although, strictly speaking, it is incorrect to speak of dermal lesions of the oral mucosa, where dermis is not present, it is nevertheless appropriate to refer to nevus of the intradermal type in mucous membranes. The authors wish to thank Prof. Dr. translation of the original manuscript material. Appreciation is also extended tistry, Faculty of Dentistry, University assistance with the photomicroscopy.
H. M. Dick, University of Alberta, Canada, for the English and for assistance in the interpretation of the histologic to Prof. Dr. F. F. Eifinger, Division of Restoration Denof Cologne, and Mr. Werner Unshelm, Leitz, Cologne, for
REFERENCES 1. Allen, A. C.: Skin. In Anderson, W. A. D.: Pathology, ed. 6, 1971, The C. V. Mosby Company, pp. 16541664. 2. Bhaskar, S. N.: Synopsis of Oral Pathology, ed. 4, St. Louis, 1973, The C. V. Mosby Company, pp. 387-392. 3. Colby, R. A.: Color Atlas of Oral Pathology, ed. 1, Philadelphia, 1956, J. B. Lippincott Company, p. 21. 4. Comerford, T. E., Jr, de la Pava, S., and Pi&en, J.: Nevus of the Oral Cavity, ORAL SURG. 17: 145- 15 I. 1964. 5. King, 0. H., et al.: The Frequency of Pigmented Nevi in the Oral Cavity, ORAL SURG. 23: 82-90, 1967. 6. Langer, E.: Histopathologie der Tumoren der Kiefer und der Mundhohle. ed. 1, Stuttgart, 1958, Georg Thieme Verlag, pp. 111-115. 7. Lever, W. F.: Histopathology of the Skin, ed. 3, Philadelphia, 1961, J. B. Lippincott Company, pp. 27-28, 575-582. 8. Masson, P.: My Conception of Cellular Nevi, Cancer 4: 9-38, 1951. 9. McCarthy, P. L., and Shklar, G.: Diseases of the Oral Mucosa, New York, 1964, McGraw-Hill Book Company, Inc., pp. 296-297. 10. Meyer, W.: Histologie der Mundhiihle. In Haupl, K., Meyer, W., and Schuchatdt, K.: Die Zahn-, Mundund Kieferheilkunde, ed. 1, Miinchen, 1958, Urban und Schwatzenberg, pp. 233-235.
02 Gutmann et al.
Oral Surg. January, 1978
11. Rotter, W., and Lapp, H.: Pathologische Anatomie des Mundhohlenbereiches. In Haupl, K., Meyer, W., and Schuchardt, K.: Die Zahn-, Mund- und Kieferheilkunde, ed. 1, Miinchen, 1958, Urban und Schwarzenberg, pp. 1011-1013. 12. Shafer, W. G., Hine, M. K., and Levy, B. M.: A Textbook of Oral Pathology, ed. 3, Philadelphia, 1974, W. B. Saunders Company, pp. 84-86. 13. Thoma, K. H., and Goldman, H. M.: Oral Pathology, ed. 5, St. Louis, 1960, The C. V. Mosby Company, pp. 1471-1476. 14. Tiecke, R. W.: Oral Pathology, New York, 1965, McGraw-Hill Book Company, Inc., pp. 451-453. 15. Waldron, C. A.: Oral Epithelial Tumors. In Gorlin, R. J., and Goldman, H. M.: Thoma’s Oral Pathology, ed. 6, St. Louis, 1970, The C. V. Mosby Company, pp. 847-848. 16. Weathers, D. R.: Benign Nevi of the Oral Mucosa, Arch. Dermatol. (Chicago) 99: 688-692, 1969. 17. Weathers, D. R., and Waldron, C. A.: Intraoral Cellular Nevi, ORAL SURG. 20: 467-475, 1965. 18. Willis, R. A.: Pathology of Tumors, ed. 4, London, 1967, Butterworth & Co., Ltd., pp. 915-953.
Reprint requests to: Dr. Jorge Gutmann F. Hauptstrasse 49 5064 RBsrath, Federal Republic of Germany
T he term nevus was originally
used to designate any well-circumscribed congenital discoloration of the skin or mucosa,flat or elevated, of vascular or nonvascular origin.‘, 2, 11,I23l*, l5 The tendency today is to restrict the use of the term to lesions of the skin and mucosal comprising cells-with a melanin-producing potential29 11,12,l4 These “cellular,” “melanocytic,” or “pigmented” nevi are sometimespresentat birth, but more often they arise during puberty or early adulthood.i-3, 5-g*11-13,15-1*These lesions are thought to representdevelopmental tumorlike malformations and are thus usually consideredamong he
ha~omas.6,
9, 11, 12, 15
Nevi occur infrequently on the oral mucosabut have been reported on the lower lip, and Walgingiva, palate, upper lip, tongue and cheek.1, 2, 5, 6, 9, 11. 12, 15-17 Weathers dron,17in 1965, addedten new casesof oral nevus to a review of sixteen acceptablecases. King and associates5reported five casesin 1967. WeatherP addedsix additional casesin 1969. Isolated caseshave been reported by a variety of authors.4Oral nevi are usually of the intradermal type.2, 4, 5*9*15-17 The intradermal nevus shows a characteristic microscopic appearance.” In the upper cutis the nevus cells form groups or nests of epithelioid cells, well defined by a fibrillar connective tissue border.7, l1 Subjacent to these cell nests, the nevus cells form more cordlike structures. The deep margins may show cells which are richer in cytoplasm and have less distinct cell outlines, forming syneytial masseswhich diffusely infiltrate the surrounding stromal tissue.6Thus, the nevus cell usually shows an epithelioid form in the more superhcial aspect of the lesions, whereas in the deeper margins it may assumea histiocytic, fibmblastic, or Schwann cell form.7, 14*l5 In the histologic description of intradermal nevus, frequent mention is made of struc*Department of Pathology, University of Chile. **Division of Oral Surgery, “Ahnirante Nef” Naval Hospital.
76
Volume 45 Number 1
lntradermal nevus associated with epidermoid cyst
77
tures which have a certain resemblance to neural structures, such as nerve endings or neurofibroma. These structures have been variously termed nevus corpuscles, lames foliacees, and neurofibromatoid and meissneroid structures and have been variably described and interpreted. 6* ‘9 l* Some authors believe that these structures represent a concentric arrangement of collagen around nevus cells; others believe that they represent a differentiation of the cytoplasm of the syncytial masses.6* ’ WilliP suggests that the meissneroid corpuscles arc formed by a partial fibrosis of nevus cell cords. A description by Rotter and Lapp” suggests that the nevus cells themselves form structures that resemble Meissner’s corpuscles. There is no concensus on the histogenesis of the cells which give rise to the common mole.’ Some authors support an exclusive epidermal origin in which the nevus cell is simply a modified basal cell which detaches from the epidermis and migrates into the dermis (Unna’s Abtropfungstheorie). In keeping with this concept, the nevus type (junctional, intradermal, compound) is dependent on age .’ Other authors support the theory advanced by Masson, in 1926, that melanocytes, as well as nevus cells, have a neural origin.7 In 1951 Massona suggested that nevus cells could originate from melanoblasts of the epidermis and from Schwann cells of the dermal nerves. According to this theory, junctional nevi would have their origin from melanoblasts of the epidermis only, whereas compound and intradermal nevi could have a dual origin from melanoblasts and Schwann cells. Further suggested possibilities are that the nevus cells may arise from the endoperineurium or specialized nerve endings similar to the Merkel-Ranvier corpuscles.” l1 Thoma,13 in reviewing Masson’s theory on the neural origin of nevus cells, suggests that the pigmented nevus is the result of proliferation of the entire terminal apparatus of the sensory nerves of the skin, especially of Meissner’s corpuscles. CASE REPORT A 4%year-old white man visited the Naval Hospital Oral Surgery Service, Valparaiso, with a painful swelling in the right buccal mucosa. He reported that a well-defined nodule had been present for more than one year and had developed after he accidentally bit his cheek. He stated that the tumor had undergone periodic recession but generally continued to enlarge. Recently the entire buccal mucosa had become suddenly swollen and painful. Clinical examination revealed a swelling which extended from the right comer of the mouth to the third molar area. The lesion was painful to pressure. Oral antibiotics and an enzyme were prescribed. Eventually a puslike material was discharged onto the mucosal surface. Following healing, a well-defined, spheroid, dome-shaped nodule, measuring about 15 mm. in diameter and situated on the occlusal line 1 cm. distal to the commissure, remained on the buccal mucosa. The mucosa covering the proximal half of the nodule was slightly irregular but showed normal coloration. A well-encapsulated, oval, bluish lesion and the covering mucosa were removed surgically as separate specimens and sent to the Department of Pathology with the clinical diagnosis of retention cyst and overlying hyperplastic mucosa. There has been no recurrence during the 5 years that have elapsed since surgical excision of the lesion on March 9, 1972. Pathologic
findings
Two formalin-fixed soft-tissue specimens were received for pathologic examination. One piece was a smooth-surfaced oval nodule, light brown in color and measuring 10 by 8 by 5 mm. The cut surface showed a central cavity filled with a white, cheesy material. The cyst wall was thin, with a smooth, pale inner surface. The second specimen was a flat piece of tissue measuring 5 by 5 by 3 mm., firm in consistency and pale in color. The epithelial surface appeared slightly verrucous.
78 Gutmann et al.
Oral Surg. January, 1978
Fig. 1. Cords of epithelioidcells in the wall of the epidermoidcyst. Histologically, the luminal surface of the cyst was lined with a thin squamousepithelium. The cyst cavity was filled with an amorphousgranular material containing somecholesterol slits. In the fibrous tissue portion of the cyst wall was an areashowing groups of elongatedepithelioid cells with dark-staining nuclei, arrangedin cords(Fig. 1). These structuresextendedto the margin of the tissue sections. Tissue sections prepared from the second specimen showed a slightly thickened surface epithelium generally characteristic of buccal mucosa. Some of the epithelial cells were large, vacuolated cells. In the subjacentlamina propria, and separatedfrom the epithelium by a band of connective tissue, were numerous cells showing a moderately variable orientation and configumtion. Some of the cells were large cuboidal cells with clear cytoplasm and a large, oval, moderately chromatic central nucleus. These cells formed nests (Fig. 2) in the superficial lamina propria and took on cordlike arrangementsin the submucosa.In addition to theseusual structuresof the cell nests,somecell groups tendedto form more distinct alveolar structures,while othersformed large rosettelike structures with nuclei forming “Olympic-ring” configurations (Fig. 4). Scattered throughout the tumor were elliptical structurescomposedof two cell types stackedperpendicularto the long axis of the structure. The predominant cell was a roughly “pear-shaped” clear cell with the nucleus situated in the thicker end of the cell and lying toward the periphery of the structure. Interspersedbetween these cells were thin cells containing elongated, darkly staining nuclei. The structurethus formed showedthe morphologic characteristicsof Meissner’s corpuscles(Fig. 3). Numerous small nerve fibers could be identified in the vicinity of the various nevus cell structures and occasionally forming part of thesestructures.At one side a rete ridge extendeddeeperinto the connective tissue, with the terminal cells showing changes suggestive of junctional nevus activity. Also presentin thesetissue sections were a number of microcysts, somein the earIy stages of development. Someof the cyst cavities were filled with eosinophilic, fine, granular, amorphous material; others contained keratin, and still others containedcalcified material, asdeterminedby von Kossa stain. Finally, two large group of sebaceouscells, with an associated diffuse mononuclear cell inflammatory infiltrate, were observedin the superficial submucosa.Special stainsgave no evidence of the presenceof melanin in any of the sections examined. The histologic diagnosis was epidermoid cyst of the mucous membraneof the cheekassociated with nevus of the intradermal type. DiSCUSSiON
Reports by Weathers and Waldron,” King and associates,5 Weathers16 and others indicate that, although the incidence of intraoral nevus is not high, the lesion is certainly
Volume 45 Number 1
Intradermal nevus associated with epidermoid cyst
Fig. 2. To the left of the striated muscle fiber are nests of news cells forming a structure suggestive
79
of a tactile
corpuscle.
Fig. 3. Groups of nevus cells forming
Meissner
corpuscle-like
structures.
more common than is suggested by the number of reported cases. More than one third of reported cases are nonpigmented. This feature, together with the variable clinical morphology of intraoral nevi, makes it probable that many are clinically diagnosed as papillomas, fibromas, or verrucae and are not submitted for histologic examination following excision. In the present case only the recognition of unusual cell clusters in the cyst wall prompted us to examine the fragment of overlying mucosa which was reported clinically as hyperplastic in appearance. Of particular interest in the present case are those structures within the nevus which are morphologically identical to Meissner’s corpuscles. In the literature frequent mention is made of the “neural” structures which form an integral part of the nevus. The interpretation of these structures, however, is not uniform. Masson,* in his article entitled “Mvi Conception of Cellular Nevi,” states that various authors have misunderstood and misinterpreted the structures which he referred to in a 1926 publication as foliated lamina or nevic corpuscles. References to “neutrofibromatoid” and “meissneroid” structures
80 Gutmunn et al.
Oral Surg. January, 1978
Fig. 4. Toward the left and right margins, center, are rosettes of nevus cells with overlapping nuclei forming “Olympic-ring” configurations.
would suggest a nonprecise interpretation of the structures very carefully defined by Masson. The result is that different authors use different terms to describe similar structures or apply the sameterms to dissimilar structures. Lever,’ for example, statesthat the fibrous stroma in the deep aspectsof an intradermal nevus may show structural characteristics similar to those of neurofibroma, with nevus cells arranged in narrow columns suggestive of neural sheets(neuroid tubes of Masson). “In other areasthe fibrous tissue may be in concentric arrangement (lames foliactes of Masson), resulting in structures resembling Meissner’s tactile bodies.” Willis’* statesthat neurofibromatoid changesseen in some moles are merely an incidental part without special histogenic significance. He believes that Masson’s “meissneroid” structuresare the result of partial fibrosis in groups of cells and are not differentiating supernumerarysensory corpuscles. According to Masson, the presence of these Wagner-Meissner-like corpuscles is a constant finding in adult intradermal nevi. The older and more prominent the nevus, the more frequently thesetransformations occur. Masson further statesthat “every nucleated region of the nevic simplasm is capableof undergoing a specialized development comparable to that characterizing the tactile corpusclesof Wagner-Meissner. This evolution has two extreme forms or stages;one simple, the foliated lamina, the other complex, the nevic corpuscle.” The nevic corpuscle resemblesa Wagner-Meissnercorpuscle; “however the thickened spiral ending, which characterizesthe latter, is absent.” Furthermore, at several places the periphery of the meissnemid corpuscle is continuous with the nevic simplasm from which it springs, whereasthe normal Meissner corpuscleis ordinarily in contact with the schwannian syncytium at the point where there is a small number of myelinated fibers that furnish its terminal expansion. In the presentcase, we were able to observethe continuity of the nevic corpuscle with Masson’s “nevic simplasm.” Furthermore, a thickened spiral ending made up of clear cells with a flattened pear-shapedmorphology stackedin a transverserelationship to the long axis of the corpuscle, with the thickened end oriented toward the periphery, was observedin thesestructures. Theseclear cells were interspersedwith thin cells with darkly staining nuclei, giving the structure all of the morphologic characteristicsof supemumerary Wagner-Meissner corpuscles.
Volume 45 Number 1
Intradermal nevus associated with epidermoid cyst
81
The presence of normal Wagner-Meissner corpuscles in rare cases of compound nevus of the fingertips and toes has been described by Masson. He states that in these areas the corpuscles may be included in the migratory zone of the melanoblasts, do not undergo any modification, and take no part in construction of the nevus. In the present case the continuity of the corpuscle with the nevic simplasm suggests that the corpuscles are derived from the formed part of the lesion. Furthermore, the location of the present lesion in the buccal mucosa supports Masson’s view that the supernumerary Meissner corpuscle formation may occur in tissues where these corpuscles are not normally present. As stated by Masson, “It would seem as if the Meissnerian potential was imparted to all cutaneous nerves but only manifested in the pathologic state in regions in which it had not been primarily exhausted by the production of normal corpuscles. ” Further features of interest in the present case were the relationship of the nevus to the epidermoid cyst and its intraoral location. Several microcysts with variable cyst contents were present between the epithelium and the superficial margin of the nevus. In one area a surface invagination of the epithelium appeared to represent an early stage of cyst formation. This feature has been described in relation to skin nevi by Thoma,13 who states that “the surface of the nevus can be covered by hyperkeratotic epithelium in which there are fissures and spaces similar to cysts.” It is apparent that this phenomenon may also occur in the oral mucosa. Whether these microcysts are in any way part of the nevus or simply represent a secondary reaction on the part of the epithelium remains an open question. Whatever the causal relationship, we believe that the cyst making up the major portion of the present case originated independent of the associated nevus. This view is based on the recognition that both epithelial rests and tumorlike malformations (hamartomas) are particularly common in embryonic lines of fusion, such as the occlusal line. In conclusion, we agree with Weathers that although, strictly speaking, it is incorrect to speak of dermal lesions of the oral mucosa, where dermis is not present, it is nevertheless appropriate to refer to nevus of the intradermal type in mucous membranes. The authors wish to thank Prof. Dr. translation of the original manuscript material. Appreciation is also extended tistry, Faculty of Dentistry, University assistance with the photomicroscopy.
H. M. Dick, University of Alberta, Canada, for the English and for assistance in the interpretation of the histologic to Prof. Dr. F. F. Eifinger, Division of Restoration Denof Cologne, and Mr. Werner Unshelm, Leitz, Cologne, for
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