Malignant Solitary Fibrous Tumor with Heterologous Rhabdomyosarcomatous Differentiation: A Case Report.
Malignant solitary fibrous tumor (MSFT) is a well-described entity, from which heterologous differentiation is extremely rare. We encountered a case of MSFT with rhabdomyosarcomatous differentiation in a 56-year-old man. This patient presented with a large mass in his posterior thigh. He had been treated with chemoradiation for sarcoma involving the cervical spine, right femoral head, and both lungs 6 months earlier. A wide excision was performed. The mass measured 10.6 cm and showed a fish-flesh cut surface with necrotic foci. Microscopically, the tumor showed heterogeneous cellularity with a hemangiopericytic vascular pattern. A hypercellular area showed spindle cells or epithelioid cells with high mitotic activity (63/10 high-power fields) and immunoreactivity for CD34 and CD99. A hypocellular area and a cystic area showed pleomorphic rhabdoid cells with immunoreactivity for desmin and myogenin. This is a report of a rare case of MSFT with rhabdomyosarcomatous differentiation and presents new histologic features of MSFT.
Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Jeong-Hwa
JH
Kwon
Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Joon Seon
JS
Song
Department of Radiology, Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Hye Won
HW
Jung
Department of Orthopedic Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Jong-Seok
JS
Lee
Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Kyung-Ja
KJ
Cho
Malignant; Rhabdomyosarcoma; Solitary fibrous tumors