Giant Perineal Solitary Fibrous Tumor: A Rare Case Report

Abstract

Background. Solitary fibrous tumor (SFT) is a fibroblastic mesenchymal tumor that was initially described from the pleura but currently arises at almost every anatomic site. It is usually benign, and surgical resection is curative. SFT involving the perineum is extremely rare. This is the third case report of a perineal SFT in the literature. Case Presentation. We reported an uncommon case of a 64-year-old man presenting with a huge perineal mass that started growing 3 years before his arrival in our service. He was asymptomatic. A contrast-enhanced CT scan revealed a heterogeneous well-circumscribed perineal mass with soft-tissue density. Invasion of the surrounding organs, distal metastasis, and lymph node swelling were absent. The complete resection of mass was done successfully. The specimen was a 23.0 × 14.0 × 8.0 cm encapsulated tumor. Mass weight was 1,170 g. After pathological analysis, we confirmed that the mass was a solitary fibrous tumor. The diagnosis was based on clinical findings and histological morphology and immunohistochemistry study. Conclusion. SFTs are usually indolent tumors with a favorable prognosis. The perineal location is extremely rare. Complete resection of the mass is the treatment of choice.

Figure 1

Perineal mass prior to surgery.

Figure 2

CT scan showing a large smoothly marginated perineal mass with uniform soft-tissue attenuation.

Figure 3

Surgical incision.

Figure 4

Perineum after mass resection.

Figure 5

Perineum after mass resection.

Figure 6

Surgical specimen.

Figure 7

Surgical specimen.

Figure 8

Hematoxylin and eosin-stained section.

Figure 9

Immunohistochemistry CD34.

Figure 10

Immunohistochemistry Ki67.

Figure 11

Immunohistochemistry STAT6.

Figure 12

CT scan done 1 year after resection: no evidence of recurrence.

Figure 13

Perineal appearance after one year of tumor resection.