Bathing trunk naevus and neurofibromatosis type 1: a unique association of Friedrich's ataxia.

A 15-year-old male presented with history of progressive instability of gait for last 6 months. General examination revealed multiple subcutaneous nodules all over the body. There was a large pigmented naevus over the lower back area along with a subcutaneous bosselated swelling over right arm. Neurological examination revealed features of gait ataxia. Plantar reflexes were extensor on both sides. Skin biopsy from the pigmented naevus showed features of melanocytic naevus. Electrophysiological studies of both common peroneal and sural nerves revealed features of axonal neuropathy. With the above clinical and laboratory findings a diagnosis of neurofibromatosis type 1 accociated with bathing trunk naevus and Friedrich's ataxia was entertained.