Proliferating pilomatricoma is a benign tumour and a rare variant of pilomatricoma that has the potential for local recurrence if incompletely excised. We report a case of giant proliferating pilomatricoma on the forearm of a 66-year-old woman. This tumour was unusually large and the presence of ulceration and rapid growth raised clinical suspicion of malignancy. The identification of shadow or ghost cells is a good clue to matrical differentiation, which can be confirmed by β-catenin immunostaining.
Keywords: matrical keratinisation; proliferating pilomatricoma; shadow/ghost cells; β-catenin.
© 2016 The Australasian College of Dermatologists.