Giant cell fibroblastoma in a 3-year-old boy.

Giant cell fibroblastoma (GCF) is a rare soft tissue tumor most often discovered during the first two decades of life. We present a case of a 3-year-old boy with a history of a recurrent lesion in the knee, the tumor growth progressively and enlarged to 2.1 cm in the previous two years before diagnosis. It involved the subcutaneous tissue, had infiltrative borders and extended into the superficial dermis. The tumor was surgically excised with free margins. There was no evidence of local recurrence, and a metastatic workup was negative after 10 years of follow up. We review herein the clinicopathologic features, histogenesis, differential diagnosis and relationship to dermatofibrosarcoma protuberans (DFSP).