Trichoepithelioma Multiplex: A Study of the Relationship between the Anatomical Location and the Histopathological Features

Trichoepithelioma multiplex is a rare, benign cutaneous genodermatosis of disputed histogenesis, consisting of tumors of trichogenic origin.
Aim: To explore the relationship between the anatomical location and the histopathological features of the trichoepitheliomas in a patient cohort with Trichoepitheliomamultiplex.
Methods: The study was conducted over the period 1995-2008 at the tertiary Dermatology and Anatomical Pathology referral centers of the University of Pretoria. The clinical and pathological features of confirmed cases were assessed. Sixty four H&E stained sections from skin lesions distributed over different body areas were examined with regard to 16 histopathological parameters for the evidence of follicular differentiation and features useful in distinguishing trichoepithelioma from basal cell carcinoma. Special stains were employed for the demonstration of mucin (PAS, Alcian blue) amyloid (Congo red) calcium (Von Kossa) and epithelial structures (AE1/AE3-CK antibodies).
Results:Trichoepithelioma multiplex was an uncommon diagnosis (20 patients). African patients were preponderant (16 vs.4 Caucasians) with slight male predominance (11 vs. 9 females). Sporadic cases prevailed (15 vs. 5 familial cases).A wide variation in the severity of the clinical presentation was observed, young black males and familial cases being more severely affected. The face was involved in all cases (30 biopsies), followed by the scalp and back (13 biopsies each) and the neck (8 biopsies). There were variations in histopathological patterns with considerable overlap between them. Special stains differentiated between the tumours from different body areas with the exception of AE1/AE3-CK antibodies. Foreign body reactions were common in lesions showing many keratinous cysts and follicular damage. Trichoepithelioma was seen in relation to a benign pigmented intradermal nevus in one biopsy and adjacent to a basal cell carcinoma in two cases
Conclusion: A positive correlation could be established between the histopathological pattern of trichoepitheliomas and the body area from which the lesions were removed.