Chest wall hamartoma. Report of two cases with secondary aneurysmal bone cysts.

Summary Chest wall hamartoma is a rare non-neoplastic benign lesion occurring in the neonatal period with particular clinical, radiological and pathological features. Histologically, it is composed of a mixture of bone trabeculae with spindle-cell stroma, chondroblast-like cells, and mature and immature hyaline cartilage. Aneurysmal bone cyst is a benign lesion that may arise secondary to several bone processes, such as giant cell tumor, chondrosarcoma, non-ossifying fibroma or osteosarcoma. We present two new cases of chest wall hamartoma with secondary aneurysmatic bone cyst formation studied with histological and immunocytochemical methods.