Giant cell tumor of acromion process with secondary aneurysmal bone cyst

Giant cell tumor (GCT) or osteoclastoma develops after attaining physeal closure with the most common sites of involvement being the ends of long bones. It is uncommon in the small bones of hands and feet and extremely rare in the flat bones. GCT is a locally aggressive tumor, but in rare cases, it may metastasize to lungs, ribs, regional lymph nodes, and skull. Secondary aneurysmal bone cyst (ABC) may also develop in some cases. Histopathological appearance is pathognomonic in most of the cases of GCT with secondary ABC formation, and immunohistochemistry is rarely needed for a confirmatory diagnosis. The usual treatment is excision or curettage with an adjuvant such as bone cement, liquid nitrogen, and phenol. Involvement of the acromion process is extremely rare. Here, we report a case of a young male having GCT of the acromion process with secondary ABC, and it is the second case reported in literature.