[Anatomoclinical and dermatoscopic study of trichoadenoma]

Area of Science:

• Dermatopathology
• Oncology
• Histology

Background:

• Trichoadenoma is an exceptionally rare follicular tumor characterized by a distinct histopathological presentation.
• Understanding its unique features is crucial for accurate diagnosis and differentiation from other skin neoplasms.

Purpose of the Study:

• To present a series of 12 trichoadenoma cases.
• To detail the anatomoclinical and dermatoscopic findings.
• To discuss these findings in the context of existing literature.

Main Methods:

• A retrospective analysis of 12 histopathologically confirmed trichoadenoma cases diagnosed between 1989 and 2018.
• Review of anatomoclinical data and dermatoscopic findings for a representative case.
• Extensive literature review.

Main Results:

• The 12 cases involved 7 women and 5 men, with an average age of 58.9 years. Lesions were most common on the head, followed by the buttocks and thighs.
• Histopathology consistently showed multiple, stacked epidermal cysts with eosinophilic keratin and stratified walls, lacking visible hair.
• Immunohistochemistry revealed positive broad-spectrum keratin markers, weak Ber-EP4 expression, and negative PHLDA1. Dermatoscopy showed small, rounded, white-yellow areas corresponding to cysts.

Conclusions:

• Trichoadenoma is a rare tumor typically affecting middle-aged adults, asymptomatic, slow-growing, and often located on the face or buttocks.
• Histological features of multiple small cystic structures suggest follicular origin.
• Differential diagnosis from trichoblastomas, desmoplastic trichoepithelioma, microcystic carcinoma, and plaque milium is essential, guided by specific histopathological and dermatoscopic markers.