title: Proliferating tricholemmal cyst: a possible pitfall in cytological diagnosis.
abstract: We report a case of proliferating tricholemmal cyst, which made difficulties in the cytological analysis of the fine-needle biopsy aspirates. This rare dermatopathologic entity is a possible diagnostic pitfall due to its close cytological resemblance to squamous cell carcinoma-the abundance of material, with predominance of squamoid cells, which form concentric structures (so-called squamous eddies), that simulate keratin pearls of well-differentiated squamous cell carcinoma. However, careful and strict application of the cytological criteria prevents overdiagnosis; the small squamoid cells that predominate in the smears occur mainly in clusters and sheets, they do not show prominent atypia, and the squamous eddies may not undergo complete keratinization.
authors.affiliation: Department of Tumor Pathology, Chair of Oncology, Medical University, Lódź, Poland.
authors.forename: W
authors.initials: W
authors.lastname: Biernat
authors.forename: R
authors.initials: R
authors.lastname: Kordek
mesh_terms: D000236:Adenoma / Q000473:pathology*; D000328:Adult; D001707:Biopsy, Needle; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D018859:Hair Follicle / Q000473:pathology*; D006801:Humans; D009333:Neck; D012878:Skin Neoplasms / Q000473:pathology*