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Onychoblastoma – Hamartoma of the Nail Unit: A New Entity?
Author(s) -
Misciali C.,
Fanti P.A.,
Iorizzo M.,
Piraccini BM,
Tosti A.
Publication year - 2005
Publication title -
journal of cutaneous pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 75
eISSN - 1600-0560
pISSN - 0303-6987
DOI - 10.1111/j.0303-6987.2005.320eu.x
Subject(s) - pathology , nail (fastener) , infundibulum , hamartoma , anatomy , biology , hair follicle , differential diagnosis , medicine , dermatology , materials science , metallurgy , microbiology and biotechnology
A 50‐year‐old Peruvian man presented with a 4–5 years history of a 1,2 × 0,7 cm subungual verrucous mass that extended from the proximal nail fold to the hyponychium of the 2nd left toe. Histology of the nail bed showed a nodular tumour with multiple structures, similar to the infundibulum of the follicles, and germ like aggregations often joined to a follicular papilla. Few scattered neoplastic cells were necrotic. The stroma surrounding the nodular aggregations was made up of delicate fibrillary bundles of collagen associated with numerous oval fibrocytes. The histological findings remind us a neoplasm with follicular differentiation: trichoblastoma. A tumor with these histological aspects on the nail unit has never been reported. We name this benign neoplasm, which probably represents an hamartoma, onychoblastoma. Differential diagnosis of this case includes basal cell carcinoma (BCC) of the nail unit which is rare and mostly localised in the nail folds. The main histopathologic findings of nodular BCC are asymmetry, ulceration and its poorly circumscription. The hair follicle and the nail share similar embryological and anatomical features and the occurrence of a tumor with follicular differentiation in the nail further demonstrates the common origin of these adnexal structures.