Epithelioid cell histiocytoma

Dermatopalholoou II

I

l

II |

Epithelioid cell histiocytoma A clinicopathologic and immunohistochemical study of eight cases Amir H. Mehregan, MD, Darius R. Mehregan, MD, and Anna Broecker, MD Monroe, Michigan

Backgroun& Epithe[ioid cdl histiocytomas histologically resemNe the int~adermal form of Spitz nevus. Objective: We have studied eight patients with epithelioid cell histiocytoma. Methods: In addition to the routine stains, histologic sections were prepared by immunohistochemical techniques for S-100 protein, HMB-45, vimentin, ~l-antitrypsin, and common leukocyte antigen. Results: Epithelioid cell histiocytoma is characterized by proliferation of angulated epithelioid cells with abundant eosinophilic cytoplasm. Immunostaining for S-100 protein and HMB-45 were negative. The majority of cells had positive reactions to staining for vimentin and oq-antitrypsin. Approximately 20% to 25% of cells also gave positive reactions to common leukocyte antigen. Conclusion: Immunostainings are useful in the differential diagnosis of epithelioid cell histiocytoma from the intradermal form of Spitz nevus. (J AM ACADDERMA'rOt~1992;26:243-6.) Fibrous histiocytomas are neoplasms that consist of proliferations of histiocytes, fibroblasts, and collagenous tissue in varying proportions.l They may be single, multiple, or eruptive. They range from a densely cellular form (histiocytoma) to the lesions that consist mainly of collagenous tissue (fibromas). 2 Among various histologic variants of histiocytomas is a relatively rare form characterized by proliferation of large angulated epithelioid cells with prominent eosinophilic cytoplasms. 3 This lesion sometimes comes into the differential diagnosis of the intradermal epithelioid cell form of Spitz nevus. We are reporting the clinical and histologic features of epithelioid cell histiocytoma in eight patients and the results of the immunohistochemical stainings in five cases. The clinical information is listed in Table I. HISTOPATHOLOGY The material examined histologically consisted of six surgically excised specimens and two punch biopsy specimens. Sections were stained with hematoxylin and eosin, and acid orcein-Giemsa. In five

From the Pinkus Dermatopathology Laboratory. No reprints available. 16/1/33612

cases, paraffin-embedded tissue sections were also used for immunohistochemical staining. The sections were stained for vimentin, al-antitrypsin, common leukocyte antigen (CLA), S-100 protein, and HMB-45. All eight lesions were slightly elevated, dome-shaped, and skin colored. None was pedunculated. They occupied the entire thickness of the dermis but did not extend into the subcutaneous fat. In seven specimens, the overlying epidermis was slightly acanthotic and hyperpigmented (Fig. 1). One lesion showed a relatively thin epidermis that appeared edematous and was covered with a thin parakeratotic crust. The growth was ill-defined and consisted of many endothelial-lined capillary blood vessels surrounded by proliferation of angulated epithelioid cells with abundant eosinophilic cytoplasms (Figs. 2-4). Binucleated and trinucleated cells were present but multinucleated giant cells were not prominent and mitotic figures were few. Elastic fibers were sparse within the lesion. Elongated fibroblasts and thin bundles of collagenous tissue were present in most areas. Other cells present included individual or small collections of lymphocytes, occasional plasma cells, and a few scattered mast cells. The sections stained for S- 100 protein showed a few positive staining cells within the epidermis and scattered in the papillary dermis. The sections stained with HMB-45 were negative. In all five cases, a majority 243

244

Journal of the American Academy of Dermatology

Mehregan et al.

~

'

....

~ ~iiiii~! 84 ~

Fig. 1. Involvement of papillary dermis with angulated cells. Epidermis is thick and hyperpigmented. There is no junctional melanocytic hyperplasia, (Hematoxylin-eosin stain; X 125.) Fig. 2. Proliferation ofangulated epithelioid histiocytes and some inflammatory ceils. (Hematoxylin-eosin stain; X400.) Fig. 3. Richly vascular area with several endothelial-lined capillary blood vessels. (Hematoxylin-eosin stain; • Fig. 4. Proliferation of angulated epithelioid histiocytes mixed with inflammatory cells. (Hematoxylin-eosin stain; • Fig. 5. Majority of cells stain positive in sections prepared by immunostaining for vimentin. (X400.)

i 84~'i

Volume 26 Number !, P a r t 1 February 1992

Epithelioid cell histiocytoma 245

Table I. Clinical data on eight patients with epithelioid cell histiocytoma No.

(yr)

Sex

Location

1

25

F

Popliteal area

2

65

M

Leg

3

63

F

Right deltoid area

4

19

M

Nasolabial fold

5

76

M

Leg

6

25

M

Back

7

49

M

Buttock

8

34

M

Right thigh

of cells within the dermis had positive reactions to stains for vimentin and al-antitrypsin (Fig. 5). Approximately 20% to 25% of the cells also gave a positive reaction in the sections stained for CLA. DISCUSSION Fibrous histiocytomas are usually single but may be multiple and are rarely eruptive. 4 They are usually firm, slightly elevated with smooth or slightly hyperkeratotic surface, and often hyperpigmented. They are rarely pedunculated. Fibrous histiocytomas occur most commonly on the trunk and extremities and occasionally on the head and neck. The growth is usually intradermal but may be deep and border subcutaneous fat (Table II). Fibrous histiocytomas are made up of proliferations of histiocytes, fibroblasts, and collagenous tissue in different proportions. 5 They are often richly vascular and may show a spotty inflammatory cell infiltrate in their periphery. Heavily cellular lesions consist of massive proliferation of histiocytes with no definite pattern. 6 In some lesions proliferating histiocytes may show a storiform pattern or appear in a palisaded arrangement. 7 Multinucleated giant cells may be few or numerous and are mainly of the foreign body type. Histiocytes and multinucleated giant cells contain lipid in the xanthomatized variety. 8 Monster cells

Si~e/Shape/Duratlon

CUnlcal diagnosis

1 cm; dome-shaped, lightly pigmented growth; 2 yr 1.2 cm; dome-shaped, skin color nodule 1.5 cm; skin color nodular growth; present 6 mo 0.8 cm; dome-shaped growth; 1 yr 0.8 cm; dome-shaped growth; 6 mo 1.0 cm; tan color nodule; 2 yr 0.7 cm; slightly elevated growth; 8 mo 0.8 cm; slightly elevated growth; 6 mo

Intradermal nevus Fibroma Fibroma Intradermal nevus Fibroma Intradermal nevus Intradermal nevus Intradermal nevus

Table II. Histologic variations of benign fibrous histioeytomas

Predominantly cellular (histiocytomas) Classic histiocytomas Xanthomatized histiocytomas Hemosiderotic histiocytomas (sclerosing hernangiomas) Storiform histiocytomas Giant cell histiocytomas Monster cell histiocytomas Epithelioid cell histiocytomas Predominantly collagenous (fibromas) Classic fibromas Sclerotic fibromas Hyalinized fibromas Angiofibromas

with large, irregularly shaped, and hyperchromatic nuclei m a y occur rarely. 9 In the hemosiderotic variety, the lesion is richly vascular, shows areas of extravasation of erythrocytes, large number of macrophages, and multinueleated giant cells that contain hemosiderin pigment granules. 1o These lesions may be blue or black and may resemble a blue nevus or a nodular malignant melanoma. Epithelioid cell histiocytoma, initially identified by Wilson

246

Mehregan et al.

Jones et al. 3 as a new a n d distinctive variant of fibrous histiocytoma, is characterized by a proliferation of angulated epithelioid cells with abundant eosinophilic cytoplasms, binucleated and trinucleated cells, and lack of multinucleated giant cell formation. This form ofhistiocytoma often enters into differential diagnosis of an intradermal epithelioid cell nevus of Spitz. Identification is based on the absence of junctional melanocytic hyperplasia and lack of tendency for the epithelioid cells to arrange themselves into nests or bundles. Immunohistochemical stainings are also helpful. In this study negative staining for S-100 protein and HMB-45 ruled out the possibility of a melanocytic lesion or a Spitz nev-us. Positive staining with vimentin, al-antitrypsin, and C L A confirmed the histiomonocytic nature of the lesion. REFERENCES

1. Niemi KM. The benignfibrohistiocytictumours ofthe skin. Acta Derm Venereol (Stockh)(Suppl)1970;50(Suppl 63): 5-66.

Journal of the American Academy of Dermatology

2. Lo WL, Wong CK. Solitary sclerotic fibroma. J Cutan Pathol 1990;17:269-73. 3. WilsonJones E, Cerio R, Smith NP. Epithelioid cell histioeytoma: a new entity. Br J Dermatol 1989;120:185-95. 4. VflanovaJR, Flint A. The morphologicvariationsof fibrous histiocytomas. J Cutan Pathol 1974;1:155-64. 5. Soini Y. Cell differentiation in benign cutaneous fibrous histiocytomas: an immunohistochemicalstudy with antibodies to histiomonocyticcells and intermediate filament proteins. Am J Dermatopathol 1990;17:269-73. 6. Gonzalez S, Duarte I. Benign fibrous histiocytoma of the skin: a morphologicstudy of 290 cases. Pathol Res Pract 1982;174:379-91. 7. SehwobVS, Santa Cruz DJ. Palisading cutaneous fibrous histiocytoma.J Cutan Pathol 1986;13:403-7. 8. Mehregan AH, Hashimoto K. Pinkus guide to dermatohistopathology. 5th ed. E Norwalk, Conn: Appleton & Lange, 1991. 9. Tamada S, Ackerman AB. Dermatofibromaswith monster cells. Am J Dermatopathol 1987;9:380-7. 10. Gross RE, Wolbaeh BS. Sclerosing hemangiomas. Am J Pathol 1943;19:533-52.