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These skin tumors are derived from the outer layers of the hair follicles. While benign tricholemmomas are very common, the tricholemmal carcinoma is exceedingly rare.


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Tricholemmal carcinoma in continuity with trichoblastoma within nevus sebaceus.

Misago N, Narisawa Y.

Division of Dermatology, Department of Internal Medicine, Saga Medical School, Saga, Japan.

Am J Dermatopathol 2002 Apr;24(2):149-55 Abstract quote

A nodule arising within the nevus sebaceus on the vertex of the scalp of a 68-year-old woman was histopathologically and immunohistochemically investigated. We also used immunohistochemistry to investigate the cytokeratin (CK) distribution of the outer root sheaths of normal terminal hair follicles.

The nodule consisted of two parts, a main exophytic part with a lobular proliferation and a small peripheral part with the features of trichoblastoma. The main exophytic lesion consisted of lobular aggregations composed of both or either basaloid cells and clear cells with the silhouette and cytology of malignancy. The columnar clear cells were aligned in a palisade at the periphery of the aggregations of clear cells, and the aggregations located in the superficial dermis were connected to the follicular infundibular structures. Almost all of the neoplastic aggregations were diffusely positive for CK7 (OV/TLR/30), and the innermost or inner cells of the neoplastic aggregations were positive for CK17; a similar staining pattern to that in the lower portion of the outer root sheath between the A and B fringes in normal terminal hair follicles. The exophytic part of the lesion was a malignant neoplasm with differentiation mainly toward the lower segment of the outer sheath between the A and B fringes of the terminal hair follicle, namely tricholemmal carcinoma.

Our case may represent a collision of two distinctive neoplasms (tricholemmal carcinoma and trichoblastoma), however, an intimate relationship between these two neoplasms also should be considered.


Eccrine porocarcinoma, tricholemmal carcinoma and multiple squamous cell carcinomas in a single patient.

Cribier B, Lipsker D, Grosshans E.

Clinique dermatologique, Hopitaux universitaires, 1, place de l'Hopital, 67091 Strasbourg Cedex, France.

Eur J Dermatol 1999 Sep;9(6):483-6 Abstract quote

A 75-year old woman without remarkable medical history presented with a large eccrine porocarcinoma of the trabelucar type located on her leg.

This tumor was associated with two invasive squamous cell carcinomas of the legs, two Bowen's diseases of her thigh and arm and multiple actinic keratoses of the face. Despite major surgery, local recurrence of the porocarcinoma was observed 6 months later. During the 3-year follow-up after a second surgical intervention, this lesion did not reccur, but the patient developed a rapidly enlarging ulcerated tumor of the forehead which proved to be tricholemmal carcinoma.

Although no carcinogenetic factor or familial history of multiple neoplasms could be evidenced, the occurrence of multiple tumors of various histogenesis over a 1 year period of time is unlikely to be fortuitous. Such an association of rare adnexal neoplasms has not yet been described.



Clear cell carcinoma of the skin: a tricholemmal carcinoma?

Lee JY, Tang CK, Leung YS.

Department of Pathology, Presbyterian-University Hospital, Pittsburgh, Pennsylvania.

J Cutan Pathol 1989 Feb;16(1):31-9 Abstract quote

We report the light and electron microscopic findings of an unusual, locally aggressive cutaneous clear cell carcinoma involving extensively the left cheek and upper lip of a 61-year-old woman. The patient remained free of recurrence 5 years after wide local excision.

Microscopically, the tumor was a poorly circumscribed and deeply invasive clear cell neoplasm characterized by large lobules and convoluted trabeculae of polygonal and columnar cells with palisading of the peripheral cells rimmed by thick basement membranes, and horn microcysts with tricholemmal keratinization. The tumor infiltrated the muscle and the salivary glands. Only slight cytologic atypia and a few mitotic figures were present. No definite ductal differentiation was found. Immunoperoxidase staining for carcinoembryonic and epithelial membrane antigens was negative. Ultrastructurally, the tumor cells were joined by desmosomes, and surrounded by thick basal lamina. The cytoplasm contained large pools of glycogen. Peculiar whorls of tonofilaments and aggregates of needle-shaped and club-shaped structures were observed in a small keratinizing focus.

The tumor showed features resembling the outer root sheath of the hair follicle microscopically. Furthermore, the lack of duct-like structures and immunoreactivity of carcinoembryonic antigen tend to favor tricholemmal over sweat gland differentiation in this tumor which possibly represents a rare example of tricholemmal carcinoma.

Tricholemmal carcinoma: clinicopathologic study of 10 cases.

Swanson PE, Marrogi AJ, Williams DJ, Cherwitz DL, Wick MR.

Lauren V. Ackerman Laboratory of Surgical Pathology, Washington University, School of Medicine, St. Louis, MO.

J Cutan Pathol 1992 Apr;19(2):100-9 Abstract quote

Tricholemmal carcinoma (TLC) is a cutaneous adnexal tumor with presumed external hair sheath differentiation.

In order to better understand the salient features of this neoplasm, we analyzed the histologic and clinical findings in 10 cases of TLC. Eight patients were males, and two were female; they ranged in age from 55-88 years. Each tumor occurred in hair bearing, sun-exposed skin, and involved the scalp, face, trunk, or upper extremities. The lesions were usually slightly raised, pale tan or reddish, and keratotic; were usually present for less than 1 year; and measured 0.4-2.0 cm. All of them were treated by wide local excision; neither recurrence nor metastasis was reported after 11 to 92 months of clinical followup.

Histologically, each TLC was composed of a lobular proliferation centered on the pilar apparatus. Cells with glycogen-rich, mucin-negative, clear or pale eosinophilic cytoplasm predominated. Brisk mitotic activity (4-39 mitoses per 10 high power fields) was typical. Involvement of the interfollicular epidermis was invariably noted, with superficial ulceration in seven tumors. Transitional zones between TLC and the adjacent epidermis were not seen, although pagetoid spread occurred in two examples. Invasion of reticular dermis was present in eight cases, with infiltration to mid-dermis in five TLC. All tumors exhibited areas of tricholemmal type keratinization; dyskeratotic cells were noted in six examples. Hyperkeratosis and parakeratosis were variably present as well. Actinic damage was a constant feature.

Despite local invasion at diagnosis, the clinical course of TLC was indolent in all cases.

Tricholemmal carcinoma: a study of seven cases.

Boscaino A, Terracciano LM, Donofrio V, Ferrara G, De Rosa G.

Institute of Pathology, University of Naples, Italy.

J Cutan Pathol 1992 Apr;19(2):94-9 Abstract quote

Seven cases of tricholemmal carcinoma (TLC), a rarely recognized cutaneous adnexal neoplasm of external hair sheath origin, are described. Most occurred on sun-exposed skin; five involved the head and neck, one the right leg, and one the right thigh. TLC had a generally short history and all were treated by local excision. The lesions had an exophytic (3 cases) or polypoid (4 cases) gross appearance.

Histologically, TLC exhibited a sharply circumscribed, lobular epithelial proliferation in continuity with the epidermis. A cytologic hallmark of these tumors was the presence of large cells with PAS-reactive, diastase-sensitive, clear or pale eosinophilic cytoplasm. High mitotic rate was a constant feature. Four tumors were infiltrative, with pushing borders, whereas three were intraepithelial. One case showed acantholysis. Immunocytochemistry revealed positivity for prekeratin and negativity for CEA and EMA, supporting the trichogenic origin of these tumors. Ultrastructural examination gave clear indication of epithelial origin for the cells but did not verify hair follicular differentiation.

Despite locally aggressive growth, the clinical course of TLC appeared indolent. Moreover, there are no cases with metastases reported in the literature.

Tricholemmal carcinoma. A clinicopathologic study of 13 cases.

Wong TY, Suster S.

Dermatopathology Division, Massachusetts General Hospital, Harvard Medical School, Boston.

Am J Dermatopathol 1994 Oct;16(5):463-73 Abstract quote

We describe 13 cases of tricholemmal carcinoma, a rarely recognized cutaneous adnexal neoplasm. The patients were nine men and four women. In general, the tumors presented as slow-growing epidermal papules, indurated plaques, or nodules showing predilection for sun-exposed, hair-bearing skin. The lesions were most frequently misdiagnosed clinically as basal cell carcinoma.

Histologically, they showed a variegation of growth patterns including solid, lobular, and trabecular; they were characterized by a proliferation of epithelial cells with features of outer root sheath differentiation, including abundant glycogen-rich, clear cytoplasm, foci of pilar-type keratinization, and peripheral palisading of cells with subnuclear vacuolization. Because of their variable growth pattern, overt cytologic atypia, abundant clear cytoplasm, occasional pagetoid intraepidermal spread, and brisk mitotic activity, these tumors may pose difficulties for diagnosis and be confused with other malignant skin tumors with clear cell changes.

Despite the seemingly malignant cytological appearance of these lesions, clinical follow-up in 10 cases showed no recurrence or metastasis over a period of 2-8 years. Thus, conservative surgical excision with clear margins appears to be the treatment of choice for these neoplasms.




Clear cell basal cell carcinoma: an unusual degenerative variant.

Barr RJ, Alpern KS, Santa Cruz DJ, Fretzin DF.

Department of Dermatology, University of California, Irvine, Orange 92668.

J Cutan Pathol 1993 Aug;20(4):308-16 Abstract quote

Clear cell basal cell carcinoma (BCC) is an unusual variant of BCC which is characterized by a variable component of large clear cells.

Twenty cases are presented which are further subdivided into pure, mixed, or metatypical categories. Although initially thought to represent sebaceous or tricholemmal differentiation, electron microscopic studies demonstrated that the clear cell changes are a degenerative phenomenon, probably involving lysosomes.


TREATMENT Complete surgical removal for malignant tumors

Weedon D. Weedon's Skin Pathology. Churchill Livingstone. 1997.
Fitzpatrick's Dermatology in General Medicine. 5th Edition. McGraw-Hill. 1999.

Commonly Used Terms

Skin Cancers

Last Updated 5/14/2002

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