Rare case of mixed epithelial and stromal tumor (MEST) of the kidney and its diagnostic and therapeutic approach: A case report

INTRODUCTION AND IMPORTANCE: Mix epithelial and stromal tumor (MEST) is a benign biphasic renal lesion composed of solid as well as cystic components lining tubular and cystic spaces of kidney. There are very few cases of such variety have been reported with perspective to renal involvement. Herein we have reported a rare case of MEST involving left renal tissue and sparing surrounding tissues. CASE PRESENTATION: A 20 years old female presented to surgical outpatient department with complaint of amenorrhea and left flank pain as well as heaviness for 1 year. Patient was vitally stable and cooperative. On physical examination left flank mass was palpated and ultrasound and CT scan imaging was also showing left renal mass confined to upper, middle and lower portion of the kidney while renal capsule, adrenal gland and ureter were spared. On histological examination showed multi-cystic structures with variably sized simple cysts lined by hobnailed epithelium with clear cells. Septa show ovarian type fibrous stroma with variable inflammation and immature nephrogenic elements. A final diagnosis of MEST was made. Therefore, radical nephrectomy with trans-peritoneal approach was done. CLINICAL DISCUSSION: MEST is a benign tumor of renal tissue that is confined to the renal parenchyma rather than involvement of surrounding structures as occurred in our case. Due to benign nature of the disease involvement of renal capsule and adrenal gland is less likely. The choice of treatment is radical nephrectomy through transperitoneal approach. CONCLUSION: MEST is a rare diagnosis thought case now start reporting since last decade, however, it’s still a rare entity to be reported. USG and CT scan are investigating modalities along with histopathological correlation to reach the diagnosis.