Pilomatrixoma: features of a case diagnosed by fine needle aspiration with literature review

Pilomatrixoma [PMX] is a benign skin appendage tumor with differentiation toward hair cells, particularly hair matrix. It has classic histomorphology. However, fine needle aspiration cytology [FNAC] diagnosis may be extremely dificult and it can be mistaken for a malignant tumor. To our knowledge there are isolated case reports and some handful of series of cases reported in the literature elaborating cytologic features of PMX. We describe clinical and cytological findings in a 29-year-old male patient with skin nodule on the right upper arm. We also review the literature and conclude that identification of unique constellation of cytological features, e.g., basaloid cells, ghost cells, refractile keratin material and foreign body giant cells etc., in appropriate clinical context are most helpful in diagnosis and obviate unnecessary radical surgery