Morphological Diversity of Trichodiscomas and Fibrofolliculomas

Abstract

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.

Skin lesions of Birt-Hogg-Dubé syndrome: Clinical and histopathological findings in 31 Japanese patients who presented with pneumothorax and/or multiple lung cysts

“…In contrast, TD is likely in a more differentiated stage of the hair follicle-related appendix in which the mantle-like proliferation of epithelial strands disappears, but sebaceous glands and dense proliferation of connective tissues emerge. This coexistence of FF and TD in a skin specimen was reported previously [22]; indeed, one of our patient's skin lesions manifested both FF and TD. Recently, a dysfunction of pluripotent hair follicle bulge stem cell was considered as a factor in the development of FF and TD [23].…”

Folliculosebaceous neoplasms: A review of clinical and histological features

“…Varying degrees of cellularity have been reported. At times, changes identical to fibrofolliculoma are noted peripherally . The lesion reported as neurofollicular hamartoma (spindle cell predominant trichodiscoma) is likely a cellular variant of trichodiscoma with variable S100 positivity …”

“…At times, changes identical to fibrofolliculoma are noted peripherally. 76 The lesion reported as neurofollicular hamartoma (spindle cell predominant trichodiscoma) is likely a cellular variant of trichodiscoma with variable S100 positivity. 77 Findings in the perifollicular fibroma are subtle and require a high index of suspicion.…”

Frequency of FLCN Loss of Function Variants and Birt-Hogg-Dubé-Associated Phenotypes in a Healthcare System Population

“…9 Macroscopically, trichodiscomas and fibrofolliculomas are indistinguishable from one another and are believed to be on the same morphological spectrum along with perifollicular fibromas. 10 Acrochordons have also been described in patients with BHD, but these lesions are also common in the general population and their relationship to BHD is unclear. 9 Patients with BHD also have increased risk of developing cystic lung disease and spontaneous pneumothoraces.…”