Rare tumour presenting as a cystic lesion in an infant.

A previously healthy male infant presented with a painless skin-coloured subcutaneous upper midline back mass overlying the spine. Initial differential diagnosis included dermoid cyst and pilomatrixoma. He underwent wide excision, with histopathology confirming a plexiform fibrohistiocytic tumour with positive margins. Re-excision achieved clear margins. This case highlights a rare presentation and emphasises the importance of including this tumour in the differential diagnosis of paediatric cystic masses.