Asian Journal of Andrology | 2019
Solitary fibrous tumor of the prostate: a case report and 5-year follow-up
Abstract
showed a yellow-white, circumscribed, homogeneous rubbery mass (6 cm × 7 cm × 6 cm), with a normal compressed prostate (4 cm × 3 cm × 2 cm), without hemorrhage or necrosis on the cut section. Frozen section examination showed negative resection margins and no invasion of the seminal vesicle or regional lymph nodes. Microscopic analysis revealed proliferative spindle-shaped neoplastic cells arranged in a storiform pattern with a heterogeneous cellular density intermixed with a sclerotic collagenous matrix. The tumor cells exhibited nuclear atypia in the form of mild mitotic activity (2–5 mitoses per 10 high-power fields [HPFs]). Variation in the nuclear size and shape was not associated with normal prostatic tissue. No vascular embolus, necrosis, lymphovascular invasion, or capsula effraction were observed (Figure 1d). Immunohistochemistry showed that the neoplastic cells strongly expressed CD34 (Figure 1e), and stained positive for CD99, B cell lymphoma-2, and Ki-67 expression, but negative for progesterone receptor (PR), smooth muscle actin (SMA), tyrosine-protein kinase kit (CD117), cytokeratin-8/18 (CK8/18), and discovered on gist 1(DOG-1). After surgery, no adjuvant treatment was given. Local recurrence and progression were not found within 4 years of active clinical and radiological surveillance. However, in October 2017, CT and MRI of the abdomen and pelvis found an approximately 7.0 cm × 6.0 cm × 4.0 cm mixed signal mass in the pelvic cavity located anterior to the first sacral vertebrae level. The mass was hyperintense on T1(Figure 1f) and T2-weighted images (Figure 1g) and distinctly heterogeneous hyperintense on diffusion-weighted images with an irregular lobule margin (Figure 1h). Neoplastic invasion was not found in adjacent organs or abdominal or pelvic lymph nodes. The mass was considered a recurrence of the primary prostatic SFT without presentation of any urinary or abdominal symptoms. The patient again underwent complete surgical resection of the tumor. Histopathological analysis revealed the spindle tumor cells with more distinctly atypical hyperplasia and mitotic activity compared with the previous pathological presentation (Figure 1i). Immunohistochemistry findings were almost identical to those obtained for the primary tumor. The patient rejected further chemoradiation therapy and chose to continue active surveillance. SFTs account for <2% in the soft-tissue neoplasms of the body, commonly to see in the pleural cavity. SFTs have no gender predominance, occurring with equal frequency in men and women, with a median age at diagnosis of 60 (range 21–87) years. Prostatic SFT is not concomitant with urinary symptoms and can be difficult to differentiate from benign prostatic hyperplasia or prostate cancer.1–3 Similar to prostate cancer, MRIs can aid localization of the site of SFT Dear Editor, Solitary fibrous tumors (SFTs) originating from the prostate are extremely rare. The prognosis of patients with SFTs who undergo surgical treatment is good, but aggressive SFTs can recur, so patients should be closely followed up.1 Here, we report a 46-year-old male patient with prostatic SFT who was followed up for 5 years after surgical treatment. This study was approved by the Ethics Committee of Lanzhou University Second Hospital (Lanzhou, China). The patient provided written informed consent. In August 2012, a suspicious echoic pelvic mass arising from the prostate was detected by transabdominal ultrasound on a routine examination of a patient with no urinary symptoms or other personal or familial medical history. The patient’s renal function and serum prostate-specific antigen were normal. Computed tomography (CT) of the abdomen and pelvis revealed a 7-cm solid, circumscribed mass located closely above and possibly arising from the prostate (data not shown); the thoracic and cranial CT and bone scan were normal. Pelvic magnetic resonance imaging (MRI) showed a 6.6 cm × 6.0 cm × 6.3 cm round, circumscribed, heterogeneous mass arising from the posterosuperior of the prostate, with a distinct margin between the posterior wall of the bladder and the anterior wall of the rectum, without a distinct border from the prostate base. The bladder was repressed forward. Fat tissue between the mass and adjacent organs showed no sign of involvement, and the seminal vesicles and pelvic lymph nodes were not invaded. The mass was isointense on T1-weighted images (Figure 1a), inhomogeneous hyperintense on T2-weighted images as Prostate Imaging Reporting and Data System (PI-RADS) 3 (Figure 1b and 1c), and slightly hyperintense on fat-suppression images. Core needle biopsies guided by transrectal ultrasonography confirmed that the tumor is derived from mesenchymal tissue, resulting in a diagnosis of a prostatic solitary fibrous tumor. The patient underwent complete surgical resection of tumor and prostatectomy in September 2012. The macroscopic specimen Solitary fibrous tumor of the prostate: a case report and 5-year follow-up