An uncommon presentation of aneurysmal bone cyst in spine of scapula: a rare case report

Aneurysmal bone cyst is locally aggressive benign osteolytic lesion of the bone. It is more common in second decade of life with slight inclination to female gender. Metaphysis of long are most commonly affected. Incidence in flat-bones is <2% especially in scapula. We present a rare case of aneurysmal bone cyst of scapula with atypical radiological finding that was confirmed with pathological correlation. A 45 years old female, right hand dominant, presented with 3 months old swelling over left shoulder. There was painful restriction of terminal shoulder range of movements. On examination the swelling was 8×7 cm cystic, non-trans illuminant, fixed to scapula, no neurovascular deficit. X-ray shown eccentric lytic lesion over the supraspinous fossa with relatively more prominent soft tissue shadow. MRI image shown well defined cystic swelling with fluid filled level, lacking septations. Excision and extended curettage of lesion revealed hematogenous fluid as content. Histopathology confirmed aneurysmal bone cyst. Our case presented with all atypical features of ABC with regards to age, location and imaging. High degree of clinical suspicion and ruling out other closest possibilities like telanectatic osteosarcoma is necessary when cystic swelling around the scapula is encountered. Excision and extended curettage of the lesion is satisfactory. Periodic follow up with MRI and long-term clinical assessment for recurrence is needed.