Fine needle aspiration diagnosis of pilomatrixoma. A monomorphic population of basaloid cells with squamous differentiation not to be mistaken for carcinoma.
In a case of pilomatrixoma, an initial fine needle aspiration (FNA) biopsy of a skin lesion yielded only a monomorphic population of mitotically active basaloid cells with squamous differentiation, without anucleated ghost cells, chronic inflammatory cells or foreign-body giant cells. These findings suggested a metastatic squamous-cell carcinoma or a malignant tumor of adnexal skin. The correct diagnosis was made by repeat FNA, which yielded the basaloid cells and ghost cells characteristics of pilomatrixoma; the FNA diagnosis was confirmed by subsequent excisional biopsy. This case demonstrates that pilomatrixoma should be considered in the differential diagnosis of skin aspirates that contain a dominant population of basaloid cells. The differentiation of pilomatrixoma from malignant lesions of the head and neck region is discussed.
Institute of Pathology, Queen Elizabeth Hospital, Kowloon, Hong Kong.
K F
KF
Ma
M S
MS
Tsui
S K
SK
Chan
D001707:Biopsy, Needle; D002294:Carcinoma, Squamous Cell / Q000473:pathology; D003937:Diagnosis, Differential; D006258:Head and Neck Neoplasms / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012878:Skin Neoplasms / Q000473:pathology*