Multiple Desmoplastic Trichoepitheliomas with Ossification and Cholesterol Deposition

In the 2009 case report, a 51-year-old Japanese man was diagnosed with multiple desmoplastic trichoepitheliomas (DTs) on his face, which had been present for 20 years. These lesions were characterized by annular, hard, skin-colored plaques with a depressed center and raised edge. Histological examination of the surgically excised tumors revealed basaloid tumor cells, horn cysts, dense collagenous stroma, foreign-body granulomas, calcification, and ossification. Notably, the tumors also showed cholesterol crystal deposition, which is a rare finding in skin neoplasms and had only been previously described in one other report. The authors suggested that the ossification in DT might be related to foreign-body reactions caused by ruptured horn cysts, and that cholesterol deposition could be due to keratinous materials from ruptured cysts inducing a foreign-body reaction. This case was significant for its demonstration of secondary metaplastic ossification and cholesterol crystal deposition in DT, which are rarely reported in the literature and can pose diagnostic challenges.