Subsequently occurring leiomyosarcoma and desmoid tumor of the right thigh.

We present the case of a 44-year-old patient with a primary leiomyosarcoma of the right upper thigh, who developed a second mesenchymal lesion at the same thigh, diagnosed as an extra-abdominal desmoid tumor, some months after surgical treatment of his leiomyosarcoma. Clinically, histomorphologically, DNA cytometrically, immunohistochemically and radiologically the different histogenetic origin of the two lesions could be proven. The patient died 17 months after his first tumor diagnosis of lung metastases of his leiomyosarcoma.