Clinicopathological analysis of fibrous hamartoma of infancy: report of 12 cases

Abstract

Objective To investigate the clinicopathological features and prognosis of fibrous hamartoma of infancy (FHI). Methods Totally, 12 confirmed cases of FHI were collected from 2009 to 2014 at the Department of Dermatology, Beijing Children's Hospital. The clinicopathological features of FHI were analyzed. Results Of the 12 patients, 7 were male and 5 were female. The median age of patients was 8 months (range, 5-20 months) , with a median age at onset of 3.5 months (range, 1-12 months) , a median clinical course of 5 months (range, 1-12 months). Skin lesions were skin-colored or pink subcutaneous nodules or plaques, and were located on the trunk in 5 patients, on the extremities in 6 patients, and on the scrotum in 1 patient. Ten patients had solitary lesions, and two had multiple lesions. The largest diameter of skin lesions varied from 2 to 25 cm. Lesions rapidly progressed in 10 patients, which were soft or hard on palpation, and were usually mistaken for hemangioma, lipoma and fibroma. All the patients were treated by surgical excision. After the operation, relapse occurred in 3 patients, but not in the other 9 patients. After secondary resection, the 3 patients experienced no relapse again. Histopathological examination revealed fibrous tissue and mature fat tissue arranged in an interwoven pattern, as well as mesenchymal cells arranged in concentric circles. The tumor mainly consisted of fibrous tissue and mature fat tissue at varying ratios. Immunohistochemically, the fibrous tissue expressed smooth muscle actin (SMA) , fat tissue expressed S100, and mesenchymal cells expressed CD99. The mesenchymal cells were differentiated into fibrous tissue and fat tissue to different extents. Conclusions FHI often manifests as solitary, rapidly growing benign tumor of soft tissue located on the trunk or extremities, and mostly occurs during the first 6 months of life. The skin manifestations of FHI are usually various, but the pathological changes are characteristic. Surgical resection is usually effective for its treatment. Key words: Hamartoma; Fibrous hamartoma of infancy