Thumb Schwannoma : A Frequent Misdiagnosis.

A 32 year-old Malay lady presented with a swelling over the dorsal surface of her right thumb for 6 months. The swelling was non-tender, smooth surfaced, mobile and nonfluctuating with no bony involvement. The provisional diagnosis was ganglion cyst. Excisional biopsy did not show features of ganglion cyst as it appeared to be wellencapsulated, multi-lobulated and yellowish in colour. Histopathological examination showed that it was a schwannoma. Schwannomas are relatively rare benign tumours which are frequently misdiagnosed. In this case, it was misdiagnosed both as a ganglion and a lipoma.