Rare Tumors of Kidney

INTRODUCTION: Collecting duct carcinoma (CDC) is an extremely rare type of renal epithelial tumor that arises from the distal convoluted tubule of kidney. Prognosis of CDC is poor due to its rapid growth and widespread metastasis. It is often difficult to distinguish CDC from pelvic urothelial carcinoma and high grade papillary Renal Cell Carcinoma. Mucinous tubular and spindle cell carcinoma (MTSCC) of kidney is also a rare but low grade epithelial neoplasm. It is often misdiagnosed as sarcomatoid renal cell carcinoma, papillary renal cell carcinoma or other aggressive renal neoplasms. MATERIALS AND METHODS: This is a study of two extremely rare cases of kidney tumors conducted in a tertiary care hospital. We studied clinical presentation, location within the kidney, radiological findings, histopathological findings, immunohistochemical findings and treatment provided. CASE REPORT: A case of CDC involving the renal medulla extending up to the cortex of upper pole of right kidney and another case of MTSCC involving the middle and upper part of left kidney have been studied. Patient with CDC was a 71 year old male presented with gross hematuria, backpain, fatigue and weight loss. MTSCC was incidentally detected in a 62 year old female. Histopathological examination of the formalin fixed paraffin embedded tissue sections were done for the diagnosis of these two rare entities. Immunohistochemistry was done for exclusion of other diagnostic entities. CONCLUSION: CDC is a rare aggressive renal neoplasm which is commonly associated with nodal and distant metastasis at the time of presentation. Early diagnosis of this tumor is essential to improve the survival of the patients. Immunohistochemical analysis helps to differentiate CDC from other renal cell carcinoma (RCC) subtypes. MTSCC is a low grade hypovascular renal tumor. The diagnosis of MTSCC fundamentally depends on histopathological examination (HPE) findings. Surgical resection of the tumor is essential for long term survival. Keywords: Collecting duct carcinoma, hematuria, histopathological examination, immunohistochemistry, laparoscopic nephrectomy, renal cell carcinoma.