Atypical radiological presentation of bizarre parosteal osteochondromatous proliferation (BPOP) of the great toe.

Bizarre parosteal osteochondromatous proliferation (BPOP), or Nora's lesion, is a rare benign bone tumour that most commonly affects the bones of the hands and feet. It presents diagnostic challenges due to its aggressive imaging features, high recurrence rate and histological overlap with malignant lesions. We report the case of an adolescent girl who presented with a hard, ulcerated swelling over the distal phalanx of the right great toe. Imaging revealed corticomedullary continuity of the lesion with the underlying phalanx, raising suspicion for osteochondroma or subungual exostosis. Surgical excision was performed, and histopathology confirmed BPOP, showing binucleated chondrocytes, endochondral ossification and the characteristic 'blue bone'. No recurrence was observed during a 1-year follow-up period. This case highlights the importance of considering BPOP in the differential diagnosis of toe lesions particularly when atypical radiological features are present. Histopathological examination remains the cornerstone for definitive diagnosis.