Chondroid and osseous metaplasia in an incidental type II papillary renal cell carcinoma with extensive solid areas: an unraveled molecular character

Chondroid and osseous metaplasia in a Type II Papillary renal cell carcinoma (PRCC) with extensive solid areas is a complex histological combination that has not been reported before. A 21 years old male presented with a comminuted fracture of right femur. On hematological investigations he was found to have low RBC count and hemoglobin. Radiological examination revealed an incidental, exophytic complex solid and cystic, mass lesion measuring 7 x 6.5 x 4.9 cm with thickened walls, septation and calcification. It was completely replacing upper pole of the left kidney with extension into perinephric fat. Enlarged para aortic and hilar nodes with necrosis were also noted. Radiological diagnosis was infectious processes such as tuberculosis versus malignancy. Surgical intervention comprising left partial nephrectomy was done. Histopathology and immunohistochemical analysis yielded the above diagnosis. Cytogenetic studies did not reveal gain of chromosome 7 and/or 17 or loss of chromosome Y, a characteristic genetic profile of PRCC. This case could be representative of a unique histological variant of PRCC in which the molecular profile yet needs to be unraveled.