Solitary Fibrous Tumor in a Female Urinary Bladder

Abstract

Solitary fibrous tumors of the bladder are extremely rare especially in the females. This is the third case of SFT in a female urinary bladder. We are presenting a case of 36-years-old female who underwent a procedure for what thought to be cervical myoma. Cystectomy and bilateral ureteral re-implantation were performed. Mass showed to be solitary fibrous tumor of the urinary bladder. These tumors are rarely occur in extrapleural spaces. Only few cases had been reported in the urinary bladder including 2 in the female and 10 in the male bladder.

Introduction

Solitary fibrous tumor (SFT) comprises a histologic spectrum of rarely metastasizing fibroblastic mesenchymal neoplasm.1, 2

Overall they account for less than 2% of all soft tissue tumors.

Complete resection is required for full histopathologic evaluation.

Immunohistochemistry (IHC) is an extremely useful tool to differentiate SFT from other tumors, such as mesotheliomas and other sarcomas.³ Conventional IHC markers of SFT are helpful but they are not specific for SFT. More recently, IHC demonstration of strong nuclear expression of the C-terminal of STAT6 has been shown to be a highly sensitive and specific marker for SFT.

Case

We are presenting a case of 36 years old female who thought to have cervical myoma. She presented to ED with symptomatic anemia due to menorrhagia. Patient also reported urgency, occasional straining to void and increased abdominal girth for the past 1 year.

Imaging done including ultrasound (Fig. 1) and MRI (Fig. 2) which showed large heterogeneous solid nodule in the pelvis measuring 6.7 × 7.5 × 7.2 cm.

Figure 1.

Ultrasound shows 75 mm × 64 mm solid nodule noted abutting the anterior surface in the lower uterine segment and is protruding into the urinary bladder lumen. This has increased in size compared to the prior exam which was 52 mm × 47 mm.

Figure 2.

Sagittal MRI images showing large heterogeneous solid T2 signal intensity nodule in the pelvis measuring 6.7 cm (transverse) by 7.5 cm (AP) by 7.2 cm (craniocaudal). It demonstrates iso-enhancement of the uterine parenchyma and there appears to be connection to left aspect of cervix. It's difficult to determine if there's connection to the urinary bladder.

Her BUN and creatinine was noticed to be elevated and renal ultrasound showed severe bilateral hydronephrosis.

Successful placement of 8F 25 cm bilateral percutaneous nephrostomy catheter with pigtail in renal pelvis. Drainage of blood tinged urine on left 400 mL and minimally blood tinged urine on right 11 mL, unsuccessful attempt at ureteral stent placement due to severe ureteral tortuosity.

Later on patient underwent total abdominal hysterectomy, bilateral salpingectomy, excision of 10 cm pelvic mass noted posteriorly to the bladder with no clear attachment to the uterus, cystectomy, bilateral ureteral re-implantation and bilateral ureteral sent placement.

Pathology showed the mass to be bladder solitary fibrous tumor (uniform spindle cells in collagenous stroma, not encapsulated and focally extends to a margin of resection, mitotic activity is low (<2 mitosis/10 high power field)), no necrosis, focal staghorn vascular pattern noted. + for vimectin, CD34, BCL -2, CD99, focally mildly + for Desmin, negative for cytokeratins AEI/AE3, S100, CD10, SMA, MSA, CD117, KI-67 stains <1% of nuclei. Staining pattern confirmed solitary fibrous tumor (Fig. 3).

Figure 3.

Solitary fibrous tumor. This low power view shows a spindle cell proliferation in a dense collagenous stroma. Staining pattern confirmed SFT.

Discussion

We are presenting a very rare case of solitary fibrous tumor for few reasons:

• •SFT arising in the urinary bladder is extremely rare as only few cases had been reported.⁴
• •The case is described in a young female as this is the third reported case in a urinary bladder of a female patient.

Consent

Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

Competing interests

The authors declare that there is no financial support or relationship that may pose any conflict of Interest. The research was funded by the authors.