Solitary fibrous tumor of the anterior abdominal wall. A case report and review of the literature.

Background: Solitary fibrous tumor (SFT) is a rare mesenchymal neoplasm affecting soft tissues with a not well defined biological behavior. SFT occurs mostly in the pleura and the thorax, while extra-thoracic localization is uncommon and abdominal localization is very rare. Histologically, SFT is a well defined mass with splindle-cell proliferation in collagenous matrix with staghorn vascular network and CD34 reactive.

Case Report: A 64 years-old man with a history of recurrent gastric cancer previously treated with total gastrectomy, was admitted with contrast enhanced CT-scan diagnosis of a well demarcated oval mass of 4.8 cm with microcysts, vascularized in the arterial phase and with wash out in the tardive phase, located in the peritoneal side of right rectus abdominis muscle, suspected for metastatic gastric tumor. The patient underwent minilaparotomy and en-bloc excision of the lesion. Histologically the tumor was characterized by a hemangiopericitoma like growth pattern and the immunostaining was positive to CD34, CD99, BCL-2 and Vimentin. The definitive diagnosis was SFT with a proliferation index (Ki-67/MIB-1) <3%. In our case, chemotherapy was not indicated. At the 6-month follow-up, the patient is in good clinical conditions with no recurrence or metastasis.

Conclusions: We reported a rare case of primitive SFT located in peritoneal side of the of right rectus abdominis muscle treated surgically, in a patient previously affected by gastric adenocarcinoma. In this case, SFT showed a benign behaviour during a short term follow-up. Dimensional pattern, histopathological features and curative surgery remain the most important indicators of clinical outcome.

Key Words: Abdominal wall, Hemangiopericitoma, SFT, Solitary fibrous tumorSpindle cell.