[Giant cell tumors of soft tissue arising in surgical scars]

Giant cell tumor of soft tissue (GCT-ST) is a rare primary soft tissue tumor with low malignant potential. It is clinically and pathologically similar to the giant cell tumor of the bone. Two cases of GCT-ST in surgical scars are reported. Both tumors were initially regarded as tumor relapses of a leiomyosarcoma of deep soft tissue and a dermal in situ squamous cell carcinoma, respectively. The development of GCT-ST in surgical scars has not been observed previously. These findings suggest chronic inflammation and tissue repair as etiological factors in the development of GCT-ST. The period of time between initial surgical intervention and the development of the GCT-ST seems to be unusually short for the development of a "true" second neoplasm, which may underline the sometimes diffuse border between reactive "pseudosarcomatous" and neoplastic fibro-histiocytic lesions.