A case of sacro-coccygeal chordoma masquerading as pilonidal sinus.

Chordoma is a rare, slow-growing, but locally aggressive malignant tumour derived from the primitive notochord. Pilonidal sinus disease, characterised by communicating granulating natal cleft tracts and abscesses, is a common condition. We report a case of a sacro-coccygeal chordoma diagnosed incidentally on surgical exploration of a case of presumed pilonidal disease.