[Chest wall hamartoma of infancy: a clinicopathologic observation of five cases].

Objective: To study the clinicopathologic features, diagnosis and differential diagnosis of chest wall hamartoma of infancy. Methods: The clinical data, histopathologic features and immunophenotype of five chest wall hamartomas were analyzed, and the relevant literature was reviewed. Results: The patients' age ranged from seven months and eight days to 20 months at time of resection, although the lesions were detected in the neonatal period. The male-to-female ratio was 4∶1. Three cases were unilateral, two presented with multiple lesions; and four were located on the right side. CT-scan of the chest showed expansile soft tissue masses with heterogeneous density containing calcifications or ossifications in one or more ribs showing partial bone destruction. Patients were all treated by complete resection. Grossly, the lesions comprised solid and cystic areas, the latter showing hemorrhage. Microscopic examination revealed the solid areas were composed of islands of multilobulated hyaline cartilage interspersed within spindle or oval mesenchymal cells, waved bone and collagen fibers. Around the chondroid tissue, there were focal endochondral ossification and mucus-like background. In addition, there were areas of aneurysmal bone cyst-like changes formed by hemorrhagic dilated cystic spaces. Immunohistochemistry was generally not necessary to establish the diagnosis. Conclusions: Chest wall hamartoma is a rare but benign lesion of infancy, showing characteristic clinicopathologic features. The prognosis are excellent after complete surgical excision.