Multilocular cystic renal neoplasm of low malignant potential: Mimicker of cystic clear cell carcinoma – urologist’s perspective

Abstract

Introduction Multilocular cystic renal neoplasm of low malignant potential (MCRNLMP) is a rare subtype of clear cell renal cell carcinoma (ccRCC) accounting for 2-4% of RCC. It is defined as a neoplasm that is composed entirely of numerous cysts surrounded by fibrous capsule and septa containing clear cells without expansile growth or mural nodules (WHO 2016). The purpose of this manuscript is to highlight that it is imperative to identify this entity by strict histological criteria and distinguish this entity from cystic ccRCC due to its low malignant potential, excellent prognosis with no recurrence or metastasis. Case report A 46-year-old male presented with continuous mild loin pain for a month. There were no lower tract urinary symptoms. Ultrasound abdomen showed left lower pole renal mass. CECT-KUB was done as a definitive investigation which showed a solitary left lower pole renal cystic lesion with enhancement of size 3.8x3.6cm (Bosniak IV). As per CT findings, the patient underwent Laparoscopic partial nephrectomy. Histopathological examination showed multiple cysts with thin septal walls possessing clear cells with low-grade nuclei. 2 years of follow-up postoperatively with imaging studies revealed no recurrence or metastasis. Conclusions The purpose of this report is to emphasize the need to identify this entity by strict histological criteria as per WHO guidelines, as imaging studies were more often inconclusive. Urologists should have an adequate understanding such an entity. Almost all cases are amenable to partial nephrectomy irrespective of size and no documented evidence of recurrence and metastasis which mandates less stringent follow up postoperatively as compared to ccRCC.

Keywords

• kidney
• tumour
• nephroma
• cystic carcinoma
• nephrectomy