Solitary Fibrous Tumor of the Soft Tissue:An Immunohistochemical and Ultrastructural Study

Abstract

Solitary fibrous tumor is a rare spindle cell neoplasm of adults that usually arises in the pleura, recently reported in other locations. The tumors occurring at soft parts are poorly recognized and often confused with other neoplasms.The CD34 antigen, originally expressed on the surface of human hematopoietic progenitor cells, has subsequently been detected in vascular endothelial cells and a diverse group of neoplasms, such as leukemias and vascular, nerve sheath, and smooth muscle neoplasms.24 ' 25 CD34 immunoreactivity has been found in other miscellaneous lesions, including hemangiopericytomas, epithelioid sarcomas, dermatofibrosarcoma protuberans, and solitary fibrous tumors of the pleura and other sites. This marker has been used as an adjuvant in the diagnosis of solitary fibrous tu- m o r 13.18.19.23.26-28 j n t n j s r e p o r t w e p r e s e n t clinicopathologic, immunohistochemical, and ultrastructural features of solitary fibrous tumors of the soft tissue in three patients, and describe its differential diagnosis for distinction from other histologically similar tumors. MATERIALS AND METHODSThe cases were collected from the files of the First Department of Pathology, University ofTokushima School of Medicine. Representative tissue samples obtained at surgery were fixed in 10% buffered formalin and embedded in paraffin. Sections of 4 |tm thickness were prepared both for staining with hematoxylin-and-eosin and for immunohistochemical examination.

Malignant Solitary Fibrous Tumor of Pleura Accompanied with First Symptoms of Chest Pain and Hemoptysis: A Case Report

“…A positive CD34 result is suggestive of an epithelial origin, and the tumor is considered to arise from differentiated mesenchymal cells in the subpleural connective tissue. 14) However, immunohistochemical expression of CD34 tends to be reduced in malignant SFTs, 15) just like ours. In some cases, it was reported that c-kit, CAM 5.2, factor XIIIa, HMB-45, AE-1, SMA, CD31 and Fli-1 were immunohistochemical negative, while there was the emergence of high-expression in Ki-67.…”

Low-grade Sarcomas with CD34-Positive Fibroblasts and Low-Grade Myofibroblastic Sarcomas

“…SFT is increasingly recognized in soft tissues [45][46][47][48]. Typically, the tumor is circumscribed but rarely encapsulated, and is composed of plump or slender spindle or rounded cells in a collagenous background ( Figure 7).…”

“…In SFT, the cells are fibroblast-like without external lamina, with rare myofibroblasts [46,60]. Occasionally myofilaments are seen in pericytes, and recently a group of tumors has been described with perivascular myoid differentiation [72].…”

Clinicopathological and immunohistochemical study of extrapleural and pleural solitary fibrous tumors: A special emphasis on the comparison between ordinary tumors and their malignant variant

“…This tumor also arises in extra-pleural sites such as the deep soft tissue of the extremities, the head and neck (especially the orbit), the peritoneum and the retroperitoneum (4,5,7,11,12). Previously, most cases of extrapleural SFTs were termed hemangiopericytoma (2,13).…”