A 25-year-old lady presented with painful periungual tumours which were associated with lytic changes of underlying terminal phalanges. She had been previously treated as a case of chronic paronychia but the problem recurred. She was subsequently diagnosed as a case of Incontinentia pigmenti which is a rare genodermatosis with mixed ectodermal and mesodermal polydysplasias, onchychodystrophy being a very rare manifestation. She was treated by excision of painful finger lesions, but there is no specific treatment for the underlying condition.