Pelvic Solitary Fibrous Tumor

1.1. Introduction: Solitary fibrous tumor is an extremely rare mesenchymal neoplasia divided into pleural and extrapleural form, the latter being considered uncommon. 1.2. Presentation of Case: We report a case of a woman suffering a pelvic solitary fibrous tumor originated in the S1 nerve root, who underwent selective embolization of the left hypogastric artery and surgical excision. 1.3. Discussion: Solitary fibrous tumor is takes place in adults, presented as an hypervascularised mass which compresses adjacent structures. Histological confirmation with immunohistochemistry is required for diagnosis. Preoperative embolization facilitates surgery in most cases, and radiation should be considered. Complete resection has a good prognosis. 1.4. Conclusion: We describe a patient with a pelvic solitary fibrous tumor, which is a rare mesenchymal neoplasia.

We report a woman suffering a pelvic SFT, who underwent preoperative embolization and successful surgical excision, with no recurrence after 24-month follow-up. The importance of this report is that SFT is an extremely rare mesenchymal neoplasia.

3. Presentation of CaseA 48-year-old woman with no medical history was referred to evaluate and treat a pelvic mass found during a gynaecological examination. CT and MRI reported a well defined and hypervascularized an extraperitoneal pelvic tumor placed on the left side, adjacent to the hypogastric vessels. The mass, which measured 8.3 x 6 cm, was causing uterine and rectal medial displacement and extended towards left S1 foraminal, without affecting the bone (Figure 1) [1]. Fine needle puncture-aspiration showed predominance of spindle-shaped cells with mild atypia and isolated mitosis, compatible with SFT. The patient underwent selective embolization of the left hypogastric artery, achieving its complete occlusion (Figure 2). After 48 hours, complete resection of the neoplasia was successfully performed. The mass was originated in the left S1 nerve root and during the surgery, it was released from the adjacent organs which were not infiltrated. In the postoperative period, the patient developed neuropathic pain, disability in left foot dorsiflexion and equinus deformity, as a result of the S1 nerve root resection. The resected specimen measured 71 x 65 x 32 mm (Figure 3), exhibited mesenchymal spindle-like cells proliferation (Figure 4) and included peripheral nerves. Immunohistochemical analysis demonstrated cells positive for CD34, collagen type IV and Ki-67 less than 2%. On this basis, SFT was diagnosed. After 24-month follow-up, no recurrence has been found and neurological sequalae has significantly improved with rehabilitation.80% five-year and 70% 10-year survival rate. On the other hand, 15-20% of patients present local recurrences and metastasis (lung, bone and liver) even 10 years after surgery, therefore a long-term follow-up with chest-abdomen-pelvis CT examination should be performed [2].

5. ConclusionSFT is a rare mesenchymal neoplasia. In this case report, we describe a patient with a pelvic SFT who underwent preoperative embolization to facilitate surgery, with no recurrence after 24-month follow-up [3,4].

6. AcknowledgementsThe authors wish to thank the patient who kindly gave consent for the case to be presented in this manuscript, and staff of our Department of Surgery for their continuous support and guidance.

7. FundingThis research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

References 1. DeVito N, Henderson E, Han G, Reed D, Bui MM, Lavey R, et al. Clinical Characteristics and Outcomes for Solitary Fibrous Tumor (SFT): A Single Center Experience. PLOS ONE 2015; 10(10): e0140362. dx.doi.org/10.1371/journal.pone.0140362.

2. Yokoyama Y, Hata K, Kanazawa T, Yamaguchi H, Ishihara S, Sunami E, et al. Giant solitary fibrous tumor of the pelvis successfully treated with preoperative embolization and surgical resection: a case report. World J Surg Oncol 2015; 13(1): 164. dx.doi.org/10.1186/ s12957-015-0578-6.

3. García-Amador C, De La Plaza R, Ramia JM, Guerra M, Arteaga V, Valenzuela J. Pelvic Solitary Fibrous Tumor. J Gastrointest Surg. 2018; 22(8): 1448-1449. dx.doi.org/10.1007/s11605-017-3651-3.

4. Bruzzone A, Varaldo M, Ferrarazzo L, Tunesi G, Mencoboni M. Solitary fibrous tumor. Rare Tumors 2010;2(4):183–185. dx.doi. org/10.4081/rt.2010.e64.

Farré SP. Pelvic Solitary Fibrous Tumor . Annals of Clinical and Medical Case Reports 2021