Abstract
Clear Cell Sarcoma of Kidney (CCSK) is known for its morphologic diversity, aggressive behaviour, tendency to recur and metastasis to bone. Amongst the various morphologic subtypes, anaplastic CCSK is associated with worse prognosis. Here, we report a case of this rare variant of CCSK. A five-year-old boy presented with history of lump and pain in abdomen since one week. The Computed Tomography (CT) scan revealed a large mass occupying the middle and inferior pole of right kidney. The clinical impression was Wilms tumour. Nephrectomy specimen was received and the diagnosis of CCSK anaplastic variant was offered only after excluding the differentials and after performing ancillary tests such as Immunohistochemistry (IHC). Thus, this case emphasizes the diagnostic challenges on morphology and the essential role of IHC in arriving at a definitive diagnosis, because failure to do so may deprive the child from optimal treatment.