Multiple trichoepitheliomas: A rare occurrence.

Trichoepitelioma is an extremely rare cosmetically disfiguring condition usually affecting the females. Trichoepitheliomas are benign lesions seen on the face, which are thought to derive from the hair follicle. Malignant transformation to basal cell carcinoma is rare and occurs late in the course of the disease These lesions are often misinterpreted and diagnosed clinically as neurofibromatosis or histpathologically as basal cell carcinoma. We report a case of multiple trichoepithelioma occurring in a male patient. The patient presented with multiple dermatologic growths on the face with varied histopathological presentations which have been described in detail.

Introduction

Trichoepithelioma (TE) was first categorized by Headington and French, who described ten cases. They considered the outer sheath of the hair follicle as the site of origin of the lesion.[123] It is an uncommon tumor differentiating toward hair follicles, usually multiple and often familial with a disproportionate prevalence in females.[4] The lesions usually appear at puberty and are small rounded and rather translucent. Cheeks, eyelids and nasolabial folds are common sites but other parts of the face and upper trunk and arms may be affected. Individual tumors reach a limiting size but the number may increase over the years. Continued growth and ulceration raise a suspicion of change to basal cell carcinoma.[2] Two extensive series of cases have been reported by Brownstein and Shapiro, Ingrish and Reed agree that the trichilemmoma is usually an asymptomatic and solitary tumor of the face that often occurs later in life. When multiple, it may represent one of the clinical features of Cowden disease.[5]

Case Report

A 52-year-old male reported with the chief complaint of multiple growths on the face for 25 years. On examination multiple dome shaped growths of varying sizes from 5 mm to 2 cm, soft to firm in consistency, non tender, non indurated were observed. In addition the patient had multiple brownish black pigmentations on the hands and back [Figure 1a-d]. No other contributory medical history was reported by the patient. The patient was moderately built and vital signs were within the clinically acceptable range. With the above features a clinical differential diagnosis of neurofibromatosis was considered. Two lesions, one from region lateral to the left ala of the nose and one lesion from above the right eyebrow, were excised. The gross specimen was 1.2 × 1 × 1 cm in size and brownish black in color [Figure 2]. Histopathological examination of the lesion revealed cystic areas that consist of central keratinaceous material surrounded by basophilic cells resembling basal cell carcinoma [Figure 3a]. Tumor islands composed basaloid cells showing peripheral palisading arranged in solid islands, adenoid and lace-like pattern, surrounded by a moderately cellular stroma and condensation of mesenchymal cells around tumor islands in some areas [Figure 3b] Cystic areas contain keratin surrounded by basophilic cells and proliferations from the wall of the horn cyst [Figure 3c and d]. Due to the varying histopathological features of the specimens obtained during the initial biopsy procedure, surgical excision of the lesions located on the right eyebrow and forehead region were carried out [Figure 4a]. The gross specimens which measured approximately 1 × 1 × 0.5 cm contained cheesy material within [Figures 4b and c]. Histopathological examination of the lesion on the eyebrow revealed solid areas resembling basal cell epithelioma with cribriform pattern [Figures 5a and b] and central melanin pigmentation [Figure 5c]. Whereas hisopathological examination of the lesion on the forehead revealed central keratin filled cystic areas, lined by stratified squamous epithelium with cells with eosinophilic cytoplasm and a vesicular nuclei, basal cells with hyperchromatic nuclei and a granular layer [Figure 6a]. Cord-like proliferation of basaloid cells was seen in one area of the lining [Figures 6b and c]. Based on the above histopathological findings a diagnosis of multiple trichoepithelioma was made.

Figure 1

(a) Multiple dome shaped growths of varying sizes; (b and c) Multiple brownish black pigmentation on the hands and back; (d) The site of excision of lesion

Figure 2

The gross appearance of the excised specimen

Figure 3

(a) H and E, [×100] Section showing cystic areas that consist of central keratinaceous material surrounded by basophilic cells resembling basal cell carcinoma; (b) H and E [×400] Section showing tumor islands composed of basaloid cells with peripheral palisading arrangement in solid islands, adenoid and lace-like pattern, surrounded by a moderately cellular stroma and condensation of mesenchymal cells around tumor islands in some areas. (c and d) H and E [×40] Section showing cystic areas containing keratin surrounded by basophilic cells and proliferations from the wall of the horn cyst

Figure 4

(a) Photograph showing the site of second surgical excision; (b) Photograph of the gross specimen; (c) Photograph of the specimen section showing cheesy content

Figure 5

(a) H and E [×40] and (b) H and E [×100] Histopathological section showing solid areas resembling basal cell epithelioma with cribriform pattern. (c) Histopathological section showing central melanin pigmentation

Figure 6

(a) H and E [×40] Histopathological section showing central keratin filled cystic areas, lined by stratified squamous epithelium with cells with eosinophilic cytoplasm and a vesicular nuclei, basal cells with hyperchromatic nuclei and a granular layer. (b) H and E [×100 ], (c) H and E [×400] Cord-like proliferation of basaloid cells seen in one area of the lining

Differential diagnosis considered in this case were TE, Trichofolliculoma and basal cell carcinoma (BCC). Trichofolliculoma represents aborted and disrupted attempt at follicle formation, which commonly affects adults and presents as a solitary lesion on the face. Usually a dome-shaped nodule showing a central pore with wool like tuft of immature, usually white hair is highly diagnostic. The present case presented multiple lesions and none showed the central pore with immature hair and hence the diagnosis of trichofolliculoma was ruled out.

BCC may show similar features but the characteristic retraction artifact seen in BCC was absent and the presence of papillary–mesenchymal bodies, which is characteristic of TE was seen in the present case.

Discussion

TE is a benign cutaneous tumor that originates from hair follicles and may be solitary or multiple, familial or non-familial.[67] TE is an extremely rare condition; dermatopathology laboratories in the US have reported only 2.14 to 2.75 cases per year.[8] Although both males and females receive equal genes (autosomal dominant), females are most affected because of low penetrance.[9]

The lesion of TE is usually well circumscribed on histologic examination.[10] Horn cysts represent the most characteristic histologic feature, though absent in some lesions which consist of a fully keratinized center surrounded by basophilic cells. Frequently few layers of cells with eosinophilic cytoplasm and large, oval, pale, vesicular nucleus situated between the basophilic cells may be seen. As the second major component of multiple TEs, tumor islands composed of basophilic epithelial cells similar to basal cell epithelioma are arranged in a lace-like or adenoid pattern. These tumor islands show peripheral palisading of cells, surrounded by moderate number of fibroblasts. Both adenoid and solid areas show invaginations which contain numerous fibroblasts resembling hair papillae called the papillary mesenchymal bodies which is an important differentiating feature.[10]

In trichoblastomas, CD10 typically highlights the peritumoral stroma, including papillary mesenchymal bodies, with minimal patchy staining of basaloid cells. In contrast, in BCC, the stroma is negative and basaloid cells variably stain strongly positive with CD10. Diffuse Bcl-2 positivity is reported in BCC, whereas the basal layer alone is highlighted in TE. However some authors have found this to be variable and unreliable in practice.[11]

Trichoepithelioma variants

The desmoplastic variant, as its name indicates, is characterized by a prominent, sclerotic stroma.[12] It occurs in the same population as the classic type and presents as a plaque located in the same anatomical areas as the classic form. Histologically, it shows narrow strands of tumor cells, a desmoplastic stroma, and keratinous cysts. Pleomorphism, palisading, or peripheral clefting are not seen. Features favoring desmoplastic TE include a rim of compact collagen around groups of epithelial cells, granulomas, calcification of cornified cells within cysts, absence of necrotic neoplastic cells, and only rare mitotic figures. In contrast to BCC, fibroblasts surrounding TE nests do not express the matrix metalloproteinase stromelysin-3 (ST-3).[13] The solitary giant variant is characterized by deep involvement of the reticular dermis and subcutaneous tissue.

Management

Slow growth is characteristic of TE. Solitary lesions can be excised. In the case of multiple tumors, this surgical approach may not be feasible. Split-thickness skin grafting, dermabrasion, electro-surgery and laser surgery have been proposed, but the results of these procedures vary.[14] Management of either form (i.e., solitary, multiple/hereditary) by superficial biopsy is usually adequate. Solitary lesions are treated by local excision with 2 mm margin with subcutaneous layer deep to the tumor. Multiple lesions maybe left untreated with follow up. However it is best to remove all lesions if it is practical to do so.

When the multiple facial lesions are surgically flattened by dermabrasion or laser therapy, they tend to re-grow into elevated papules or nodules.[15] This re-growth may occur rapidly within months, or it may take several years. Partial destruction is usually followed by re-growth. The persistence or recurrence of tumors is a complication, and scarring may occur after treatment. Partial removal may result in persistence or recurrence. In the present case, the patient has now been followed up for 3 years, with no signs of recurrence till date.

Any suspicion of malignant change calls for adequate excision and histopathological examination. Although rare, tumors can transform into high-grade carcinomas and mixed (epithelial/sarcomatous) tumors.[16] Familial TE has shown an aggressive, recurrent behavior in rare cases.

Some patients find a prolonged cosmetic improvement to be worthwhile even if repeated procedures are necessary.