Clear Cell RCC with Lytic Bony Lesions: Metastasis or Multiple Myeloma, A Diagnostic Dilemna

Abstract

Introduction: The existence of two malignancies together is very rare. Multiple myeloma and RCC occurring together is highly uncommon. Possible reason for co-existence may be similar cytokine growth requirements however no etiology has been proven for sure. Case Presentation: We present a case with a renal lesion and bony lytic lesions suspected of being secondary osseous metastasis. However on further evaluation the bony lesions were found to be due to co-existent multiple myeloma. Conclusion: The occurrence of RCC and MM together is higher than the expected incidence. The causative etiology may be genetic abnormalities, environmental exposures or immune-related mechanisms that predispose the patient to the second malignancy. These findings are particularly relevant in the management of patients with known RCC and lytic bone lesions.