Trichoepithelioma

 Superficial folliculocystic structures and calcifications


image Deeper infiltrative-appearing cords and small islands in densely fibrotic stroma





Top Differential Diagnoses




• Basal cell carcinoma

• Microcystic adnexal carcinoma

• Trichoblastoma

• Trichoadenoma

• Sebaceoma

image
Clinical Photograph of Multiple Lesions
Multiple trichoepitheliomas image are scattered over the central face and nasolabial area presenting as flesh-colored, 1- to 4-mm papules. (Courtesy B. Hall, MD.)


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Trichoepithelioma at Low Magnification
Scanning magnification of trichoepithelioma (TE) shows irregular islands of bland basaloid cells image with prominent horn cysts image and clefts between collagen bundles image, rather than the tumor-stromal retraction artifact seen in basal cell carcinoma (BCC).

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Higher Magnification of Papillary Mesenchymal Bodies
High-power view of a TE demonstrates characteristic papillary mesenchymal bodies image invaginating into the basaloid cells. (Courtesy A. Bowen, MD.)

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Desmoplastic Trichoepithelioma
Desmoplastic TE can mimic a morpheaform BCC in some cases. However, the prominent horn cysts image and calcifications image are more consistent with a TE. (Courtesy G. Fraga, MD.)


TERMINOLOGY


Abbreviations




• Trichoepithelioma (TE)


Synonyms




• Superficial trichoblastoma


Definitions




• Basaloid proliferation with mixture of primitive follicular structures and mature infundibulocystic keratinizing areas


ETIOLOGY/PATHOGENESIS


Genetic




• Some cases are inherited as part of a genetic syndrome, including Brooke-Spiegler, familial TEs, or Rombo syndrome

• Autosomal dominant inheritance

• Present as multiple lesions, often with cylindromas and spiradenomas (Brooke-Spiegler syndrome)


CLINICAL ISSUES


Epidemiology




• Incidence
image Relatively common tumors

• Age
image Usually present in adults
– Genetic forms present in adolescence

• Sex
image Slight male predominance


Site




• Most commonly occur on face, but may involve other head and neck sites


Presentation




• Solitary or multiple papules
image Sporadic cases are typically solitary

image Inherited cases are usually multiple

image Usually small (< 5 mm), especially the sporadic cases

image Large or giant trichoepitheliomas are better referred to as trichoblastoma


Treatment




• Options, risks, complications
image Surgical excision is curative

image Should be recommended in partial biopsies in order to exclude basal cell carcinoma (BCC)


Prognosis




• Excellent; very low recurrence or malignant potential

• However, rare cases have been associated with (or progressed to) BCC


MACROSCOPIC


General Features




• Small, superficial dermal-based lesion


MICROSCOPIC


Histologic Features




• Multiple lobules and nests of basaloid cells, typically confined to superficial dermis
• Areas of infundibulocystic differentiation (keratinizing cysts) are present

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Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Trichoepithelioma
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