Stesura Seveso 177Archivio Italiano di Urologia e Andrologia 2015; 87, 2 CASE REPORT Extraintestinal gastrointestinal stromal tumor of undetermined origin: Is the mass resection a wrong approach? A case report and review of the literature Özgür Haki Yüksel, Serkan Akan, Çaglar Yildirim, Ahmet Ürkmez, Ayhan Verit Fatih Sultan Mehmet Research & Training Hospital, Dept. of Urology, Istanbul, Turkey Gastrointestinal stromal tumor (GIST) was first defined by Mazur et al. in 1983. GIST is evaluated among tumoral lesions that can be acquired or congenital. Those not associated with gastroin- testinal system are termed as extragastrointestinal stromal tumor (EGIST). EGISTs can develop on intraperitoneal spaces as omentum, mesenterium and gallbladder and they can occur on retroperitoneum, extraperitoneal (prostate) and intrapelvic organs. Herein, we present a case with EGIST in a 65-year-old male patient located in intrapelvic and retropro- static area which had no connection with gastrointestinal sys- tem as assessed by radiological methods and we discuss its treatment. We reviewed the literature and observed that ours is the first case report on a patient in which the mass was only extirpated rather than performing radical surgery. He is still at the 2. year of his follow-up period without any disease recurrence. KEY WORDS: Extragastrointestinal stromal tumor; Prostate; Mass extirpation. Submitted 10 January 2015; Accepted 19 March 2015 Summary No conflict of interest declared. CASE REPORT A 60 year-old male patient presented to the clinic of gen- eral surgery with complaints of epigastric pain, jaundice and difficulty in defecation. When radiological evidence of intrapelvic retroprostatic mass was found, he was referred to our clinic. He had undergone hypophysecto- my 16 years before with the diagnosis of pituitary ade- noma. His laboratory test results were as follows: hema- tocrit: 36%, platelet count: 373.000/mm3, serum creati- nine: 0.67 mg/dL, total testosterone: 0.24 ng/ml, pro- lactin: 0.8 ng/ml, baseline cortisol: 9 mcg/dL, total PSA < 0.01 ng/ml. Decreased luteinizing hormone levels were detected, while T3, T4, follicle stimulating hormone and results of complete urinalysis were within normal limits. The patient was receiving daily doses of 0.1 mg levothy- roxine and 2.5 mg bromocriptine. General physical examination revealed a slight rebound tenderness (Murphy’s sign positivity). Scrotal examination revealed decreased bilateral testicular volumes. During digital rec- tal examination, a rectal fibrotic mass in the prostatic lodge that could be partially palpated and presumably extending up to the proximal part of the rectum was pal- pated. Magnetic resonance imaging (MRI) of the abdomen revealed a mass lesion measuring nearly 65x68x95 mm with a central cystic and necrotic area. This mass was located on the left posterolateral part of the prostate gland associated with a decrease in the pro- static volume and its post-contrast images demonstrated a space-occupying lesion with an intense contrast uptake (Figure 1). The lesion was adjacent to the left posterolat- eral wall of the bladder. Demarcation line between some part of the mass and layers of the bladder walls was dis- rupted and also the lesion extended to the mesorectum. The adipose tissue interposed between the lesion and the rectum was effaced and the mass compressed the rec- tum. Multiple reactive lymph nodes were observed in bilateral inguinal regions. Degenerative changes consis- tent with the patient’s age were observed in bony struc- tures, which did not suggest metastases. Report of the flexible colonoscopic examination performed by the department of gastroenterology denied the presence of a macroscopic mass lesion. Positron emission tomography (PET/CT) disclosed a left paramedian mass lesion with a soft-tissue density over the prostatic lodge with its largest DOI: 10.4081/aiua.2015.2.177 INTRODUCTION Interstitial cells of Cajal (ICCs) have been defined by Ramon Cajal nearly 120 years ago as primitive neurons of the intestines (1). Various studies have shown that ICCs are pacemaker cells which ensure control of peristaltism in the gastrointestinal system (GIS) (2). Presence of ICCs in the urinary system was firstly demonstrated in 1999 (3). In two separate studies performed by Exintaris and Shafik, the authors proposed the presence of sponta- neous contractile activity in the stromal layers of the prostate of guinea pigs and dogs (4, 5). Similarly pres- ence of c-kit positive staining interstitial cells in the human prostate has been shown (6). It has been demon- strated that these cells can be pacemaker cells triggering slow-wave spontaneous electrical activity. It has been also suggested that they can be responsible for the trans- port of glandular secretion from prostatic acinar cells into its major and minor ducts and finally into urethra (4). Herein, a case of EGIST located in retroprostatic area without any association with gastrointestinal system was discussed and evaluated in the light of the literature. Yuksel_Stesura Seveso 02/07/15 11:40 Pagina 177 Archivio Italiano di Urologia e Andrologia 2015; 87, 2 Özgür Haki Yüksel, Serkan Akan, Çaglar Yildirim, Ahmet Ürkmez, Ayhan Verit 178 dimensions reaching 87 x 61 mm. On PET/CT, efface- ment of fat planes interposed between the mass and the rectum posteriorly, and left obturator internus muscle laterally was observed. The result of transrectal ultrasound guided biopsy was reported as gastrointestinal stromal tumor. With the aid of these data, surgical intervention was planned and real- ized under general anesthesia. Intraoperatively, a mass measuring nearly 8 cm posterior to the left side of the bladder without any association with genitourinary sys- tem and rectum was detected and resected as an intact mass from its suitable surgical cleavage and sent to pathology. pecimens excised from the anterior wall of the rectum and retroprostatic region were sent for frozen section evaluation. Frozen section examination was reported as tumor-negative, so we also excised tissues from surgical margin and sent them for histopathological examination. Immunohistochemical evaluations of the specimen were reported as follows: CD-34, CD-117 (C-KIT), vimentin positive; S-100, desmin, SMA, HHF-35, panceratinine negative and Ki-67 score was 11-12%. Histopathological and immunohistochemical findings were evaluated as high-risk malignant gastrointestinal stromal tumor (Figure 2). Postoperatively, imatinib treatment was planned. At 2 year follow-up period no radiologically detected metas- tasis was observed. Discussion and supplementary references are posted on www.aiua.it REFERENCES 1. Cajal SR. Sur les ganglions et plexus nerveux d’intestin (Abstract). CR Soc Bio. 1893; 5:217-223. 2. Rumessen J, Thuneberg L. Pacemaker cells in the gastrointestinal tract: interstitial cells of Cajal. Scand J Gastroenterol. 1996; 216:82-94. 3. Klemm MF, Exintaris B, Lang RJ. �dentification of the cells underlying pacemaker activity in the guinea-pig upper urinary tract. J Physiol. 1999; 519:867-884 4. Exintaris B, Klemm FM, Lang JR. Spontanous slow wave and concractile activity of the guinea pig prostate. J Urol. 2002; 168:315-322. Correspondence Özgür Haki Yüksel, MD (Corresponding Author) ozgurhaki@gmail.com Serkan Akan, MD Çaglar Yildirim, MD Ahmet Ürkmez, MD Ayhan Verit, MD. Prof, Dept. of Urology, Fatih Sultan Mehmet Research & Training Hospital Içerenköy/Ataşehir Tr- 34752 Istanbul, Turkey Figure 1. Magnetic resonance imaging of the mass lesion measuring nearly 65 x 68 x 95 mm. Figure 2. Histopathological appearance of the mass lesion. Yuksel_Stesura Seveso 02/07/15 11:40 Pagina 178