Asymptomatic plaque over the face in an elderly woman

CASE DESCRIPTION

A 50-year-old woman presented with an asymptomatic, slow-growing lesion over the face for 1 year. History of trauma, fever, joint pain, photosensitivity, weight loss, constitutional symptoms, and topical or systemic medications were lacking. On examination, a solitary, skin colored, non-tender, slightly indurated, compressible plaque, measuring about 1.5 × 2 cm was present below the left ala of the nose [Figure 1]. Her hematological, biochemical, and urine routine were normal. Serology for infectious diseases was negative. Chest X-ray and ultrasound of the abdomen were normal. Slit-skin smears were negative for acid–fast bacilli. A biopsy was obtained. Histopathology showed an epithelial neoplasm with tumor islands [Figure 2a]. Some of the tumor islands showed keratin cysts whereas others showed a cribriform pattern. Stroma was dense, rich in fibrocytes, and enveloped the tumor islands. Tumor islands showed peripheral palisading and at places, formation of germ and papilla structures [Figure 2b]. The cells of tumor islands were follicular germinative cells lacking nucleoli, showing regular distribution of chromatin.

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Figure 1:

Skin-colored plaque over the face.

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Figure 2:

(a) Section showing tumor islands (black arrows) and keratin cysts (orange arrows) (Hematoxylin and eosin, 40x). (b) Section showing tumor islands with peripheral palisading arrangement (black arrows), keratin cysts (orange arrow), and dense stroma (blue circle) (Hematoxylin and eosin, 100x).

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WHAT IS THE DIAGNOSIS?

DISCUSSION

Trichoepitheliomas (TE) are an uncommon, benign, adnexal neoplasms that originate from the hair follicles and most commonly present as solitary papule, but in the familial setting, they appear in clusters, characteristically involving the central face and/or the scalp. They present with varying sizes, ranging from small papules that are of minor cosmetic relevance to multiple tumors that can lead to functional impairment such as visual obstruction.¹ Usually, seen in children or young adults,² there are three forms of TE: solitary, multiple, and desmoplastic. Solitary form is more common in young adults. It is located on the mid-facial area and in some cases around the nasal area. TE rarely can reach a size of over 1 cm in diameter and can be found on the neck, scalp, or trunk.

Multiple TEs are encountered in Brooke–Spiegler syndrome and Rombo syndrome. Brooke–Spiegler syndrome has an autosomal dominant transmission. Mutation of the gene CYLD on chromosome 16q 12–13 is involved. This syndrome is characterized by the presence of multiple TE, cylindromas, and spiradenomas on the face and cervical region. Rombo syndrome is dominantly inherited, characterized by vermiculate atrophoderma, hypotrichosis, TEs, basal cell carcinomas, and peripheral vasodilatation with cyanosis.³ PTCH gene was also thought to be linked to the etiopathogenesis of multiple familial TE, but recent evidence suggests that it is rarely mutated in this disease.¹

Desmoplastic TE was first described by Zeligman in 1960 as a “solitary TE.” Brownstein and Shapiro specifically distinguished this tumor from morpheaform basal cell carcinoma and other cutaneous neoplasms.⁴ They characterized the clinical features of the lesion as an annular, firm papule that is asymptomatic and white to yellowish in color, ranging from 3 to 8 mm in diameter. The center is frequently depressed, not ulcerated, with a raised border.⁵

The definite diagnosis of TE is established by histopathological examination and it shows a high degree of differentiation toward hair structures with numerous horn cysts, abortive primitive hair papillae as well as narrow strands of tumor cells. There is a low mitotic rate, desmoplastic stroma, with a low quantity of stromal mucin.⁶ Treatment options for multiple TE include destructive/ablative techniques such as cryotherapy, dermabrasion, electro-dissection, and radiation therapy, all with variable to poor outcomes.¹

Histopathologic study is crucial for the diagnosis of this condition to differentiate it from other possible differentials such as basal cell carcinoma, Bowen’s disease, and tuberculoid leprosy. Furthermore, plaque type of TE is rare.