Solitary fibrous tumor (SFT) is a mesenchymal fibroblastic tumor that occurs anywhere in the body. Klemperer and Rabin first described it in 1931 as a localized fibrous mesothelioma [1]. Although SFT has been considered limited to affect pleura, they have also been reported to develop in various extra-pleural sites including extremities like the head and neck region, thoracic wall, mediastinum, pericardium, retroperitoneum, abdominal cavity, and other organs [2,3].

It is often difficult to make a definite diagnosis of abdominopelvic tumors by imaging alone [4]. In such a case, pathological information obtained by biopsy is useful. It seems that compared to laparotomy biopsy, laparoscopic biopsy might be more feasible for pelvic tumors. However, there is no evidence stating that laparoscopic biopsy is safer than laparotomy biopsy. Here the authors report a case with a large SFT of the mesometrium, in which a laparoscopic biopsy caused uncontrolled hemorrhage.

A 70-year-old woman was diagnosed with uterine tumor at another clinic three years ago. She was referred to Kobe University Hospital, and pelvic ultrasound examinations revealed a tumor with a 10-cm diameter in the uterus. On physical examination, a palpable tumor near the uterus was well mobile. MRI showed a well-circumscribed mass with high signal intensity by virtue of T2-weighted images and 102 mm diameters in the pelvis (Figure 1). Fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) revealed an abnormal uptake (SUVmax = 6.43) and hydroureteronephrosis (Figure 2). However, blood tumor markers were within the normal ranges, including carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), and cancer antigen 125 (CA125).

Figure 1.

— MRI of a SFT in pelvis. Pelvic MRI shows a well-circumscribed mass adjacent to the uterus. The tumor has a high signal homogeneous intensity, 102 mm in diameter on a T2-weighted image.

Figure 2.

— PET/CT of a SFT in pelvis.

PET/CT shows abnormal uptake (SUV_max = 6.43) and hydroureteronephrosis (red arrow) of the left side.

The present authors assumed that tumor resection had a high risk of ureteral injury. The pathological diagnosis made by laparoscopic biopsy was necessary for planning therapeutic strategy. Laparoscopic biopsy with three ports was performed on the patient in the lithotomy position with a gentle head-down tilt. The tumor was located in the retroperitoneum. Furthermore the authors accomplished a biopsy from tumor surface (Figure 3A). It caused spouting and massive bleeding (Figures 3B, 3C). Therefore, the authors immediately performed laparotomy and applied pressure with gauze to stop the bleeding, as it was difficult to control the bleeding using any sealing device. However, there was still continuous bleeding from tumor surface. Therefore, hysterectomy and bilateral salpingo-oophorectomy were performed that led to bladder injury. The tumor was completely removed with ureterovesiconeostomy by urologists. The operation time was 543 minutes, and the blood loss volume was 6,108 ml. The patient was then transferred to intensive care unit.

Figure 3.

— Laparoscopic biopsy.

(A) The tumor is located in the retroperitoneum. (B, C) A biopsy was performed from the tumor’s surface due to spouting and massive bleeding.

The resected tumor size was 10.7×9.7×5.7 cm. Macroscopically, the resected specimen was covered with a fibrous capsule (Figure 4A), and fibrous tissue was seen between the uterus and the tumor. The appearance of intact myometrium of the uterus suggested that the tumor originated from the mesometrium. The cut surface of the tumor showed focal hemorrhage with no necrosis and it appeared as solid yellowish-white. There were diffused proliferating short spindle cells comprising a capillary vessel histologically, which exhibited a hemangiopericytoma-like pattern without significant cytological atypia (Figure 4B).

Figure 4.

— Macroscopic, microscopic, and immunohistological tumor findings. (A) The resected tumor measures 10.7×9.7×5.7 cm. (B) Microscopic findings show diffuse proliferating short spindle cells containing a capillary vessel, which exhibit a hemangiopericytoma-like pattern without significant cytological atypia (H&E, original magnification ×100). (C, D) Immunohistological staining reveals tumor cells are positive for CD34 and STAT6 (original magnification ×100).

The mitosis rate was low (<1/10 high-power fields), and only 2% of tumor cells were MIB-1 positive. On immunostaining, the tumor cells tested strongly positive for CD34 (Figure 4C) and STAT6 (Figure 4D). On the contrary, they tested negative for cytokeratin AE1/AE3, α-smooth muscle antigen (SMA), desmin or S-100.

Written informed consent was obtained from this patient for publication of this case report and any accompanying images. The patient’s anonymity has been preserved.

The definite diagnosis of abdominopelvic tumors is quite difficult by imaging alone [4]. Abdominopelvic tumors are considered to be larger, with a higher malignant potential than those in the pleura [5]. Histological criteria of malignancy composed of high cellularity, high mitotic activity (> 4/10 HPF), nuclear pleomorphism, and necrosis [6]. In the present case, the tumor was histologically diagnosed as benign extrapleural SFT. The tumor was completely resected from the pelvic cavity. There was no regional recurrence within the 24 months of the operation.

The present authors perform laparoscopic biopsy for the diagnosis of ovarian cancer before initiating the first-line therapy in several cases for safety reasons. The definitive diagnosis by imaging is often difficult, especially in cases where tumor is present in deep pelvis. Therefore, biopsy findings are crucial to determine a therapeutic strategy. In cases of high risk of injury to the adjacent organs, surgery should automatically be avoided, Depending on the results of biopsies, the present authors usually adopt interval cytoreductive debulking surgery after neoadjuvant chemotherapy for an ovarian malignant tumor; an operation on deliberate preparation including the support of other medical divisions for a uterine malignant tumor; and gonadotropin-releasing hormone agonists (GnRHa) therapy before surgery for hormone-dependent tumors such as the uterine leiomyoma. SFT in a pelvic cavity is a rare case [2,3]. The biopsy is essential for the definitive diagnosis of SFT because the imaging adjacent to the uterus is extremely difficult in the case of SFT. However, blind biopsy should be avoided when there is strong potential of malignancy.

Prophylactic artery embolization is recommended to resect a hypervascularized tumor [7]. Laparoscopic treatment after the diagnosis of a benign tumor is technically feasible for certified surgeons [8]. However, there is no evidence regarding the efficacy of prophylactic artery embolization before the biopsy. Also, resection of SFT in the pelvis is likely to cause massive hemorrhage during surgery [9]. In the present case, the bladder was injured as resection of the tumor was performed without controlling the hemorrhage. The pathological results confirmed it as benign tumor, and the resection was accomplished. As SFT is hypervascularized tumor, laparoscopic biopsy should be performed with careful preparation of countermeasures for hemorrhage.

The authors would like to thank Enago (www.enago.jp) for the English language review.