Morphological diversity of trichodiscomas and fibrofolliculomas

Trichodiscomas (TDs) and fibrofolliculomas (FFs) are hamartomatous tumors, which are usually small facial papules; they are frequently a disease marker for Birt-Hogg-Dubé syndrome, their recognition is important because of this association. Some believe that TD and FF is the same lesion, others have proposed the term "mantleoma" to include the morphological continuum of both of these lesions. Recently, some variants (eg, spindle cell TD, TD with lipomatous metaplasia) have been described. The authors attempt to describe a review of cases with combined features of TF and FF, as well as the recently described variants, and variants not previously described to our knowledge (myxoid/mucin predominant, pseudocartilaginous, sclerotic/fibrotic, prominent apocrine/eccrine, leiomyoma-like, with vascular proliferation). It has been hypothesized that the hair bulge stem cells may be responsible for the broad spectrum of histological variation in these tumors.