Solitary Fibrous Tumor in the Perianal Region: Report of Two Cases With an Atypical Location

Jorge Alejandro Gonzalez,Sergio Cervera-Bonilla,Oscar Messa Botero,Elio Sanchez

doi:10.7759/cureus.12887

Abstract

A solitary fibrous tumor (SFT) is a mesenchymal neoplasm of spindle cells, initially described in the pleura. The World Health Organization (WHO) classifies the solitary fibrous tumor as a neoplasm with intermediate biological potential. Diagnostic images are essential for the diagnostic and therapeutic approach in this entity. The standard of treatment for this type of lesion is surgical resection with oncological margins larger than 1 cm. The solitary fibrous tumors located in the perianal, perineal, and pelvic regions are infrequent and represent a challenge in the clinical approach, mainly because the manifestations are nonspecific. Given the low incidence of this type of neoplasm, we present two cases of SFT in the perianal region managed in a high-complexity hospital.

Highlights

A solitary fibrous tumor (SFT) is a mesenchymal neoplasm of spindle cells, which was initially described in the pleura and has received different names according to the histological findings that are observed; it has been described in other locations such as the abdominal region and soft tissues [1,2,3]
Several studies have attempted to identify clinical and paraclinical factors that allow the differentiation of the SFTs with benign behavior from those that behave more aggressively and with malignant characteristics; among them stand out: age, location, large size tumors, high mitotic rate (>4/10 high-power field (HPF)), high cellularity, and cell pleomorphism [2,5,6]; there is much controversy and heterogeneity in the available literature regarding the factors associated with malignancy and increased risk of relapse
It has been described that surgical resection remains the standard treatment, approximately 20% of the patients who are taken to surgical treatment have a subsequent local recurrence [7]; for this reason, the use of adjuvant therapy in SFT has been proposed from some time ago

Summary

Introduction

A solitary fibrous tumor (SFT) is a mesenchymal neoplasm of spindle cells, which was initially described in the pleura and has received different names according to the histological findings that are observed; it has been described in other locations such as the abdominal region and soft tissues [1,2,3]. The anatomopathological findings described a tumor of 4 x 3 cm, of spindle-cell type, predominantly hypocellular with abundant extracellular collagen (Figure 5) with less than four mitoses x 10 HPF, without the presence of necrosis or anaplasia, and no dedifferentiation areas were identified; the immunohistochemical study showed reactivity for CD34 and STAT-6 (Figure 6) with negativity for S-100, SOX-10, and CD31. With these findings, it was concluded that it was a solitary fibrous tumor of low risk. No clinical or imaging signs of locoregional or distant relapse have been identified and there was no compromise of fecal continence

Discussion

Conclusions

Disclosures

Findings

Fletcher CDM

Chan JK