BENIGN SOLITARY FIBROUS TUMUOR OF RETROPERITONEUM – A CASE REPORT.

Abstract

Solitary brous tumuor (SFT) are rare variety of mesenchymal tumours. Most common location of SFT is pleura. 30% to 40% of SFTs occurs in extra-pleural regions (1). Retroperitoneal SFTs are very rare tumours with around 9 cases reported worldwide (2-7). It can be benign or malignant depending on cellularity, mitotic activity, necrosis and ki-67%. More than 4/mitosis per HPF is considered malignant (8). A 34-year-old lady presented with mass in right side of abdomen measuring 20x10cm, hard in consistency, mobile, no movement with respiration and crossing the midline. Ultrasound abdomen showed 20x11.5cm mass in retroperitoneum with compression of right kidney pelvis causing hydronephrosis. CECT abdomen showed 19.5x16.3x13.6cm mass in the retroperitoneum closely abutting right renal pelvis, adjacent pancreas, duodenum, inferior vena cava, psoas muscle posteriorly and abdominal wall anteriorly. After multidisciplinary tumour discussion surgery was planned for the patient. Patient underwent laparotomy with excision of retroperitoneal mass and right nephrectomy as the mass was densely adherent to right kidney. On histopathological examination of tumour spindle cells arranged in loose fascicles, thinned out wavy nuclei, eosinophilic cytoplasm with less than 3mitosis/ HPF was seen. On immunohistochemistry (IHC) tumour was diffusely positive for CD34 and STAT 6. Tumour was negative for SMA, Desmin, S-100, MUC4 and Beta-catenin. Ki-67% was 0-1%. Thus, a diagnosis of benign solitary brous tumour of retroperitoneum was made