ALK rearrangements-associated renal cell carcinoma (RCC) with unique pathological features in an adult.

We report an exceptional case of renal cell carcinoma (RCC) associated with ALK translocation in an adult. The tumor was located in the left kidney and measured 4cm. The tumor was composed of sheets of large eosinophilic cells with frequently intracytoplasmic vacuoles. The nuclei were large with a nucleolar grade 3. At immunohistochemistry, tumor cells were diffusely positive for PAX8 and vimentin and focally stained with CK7. ALK immunostaining was diffuse and fluorescent in situ hybridization showed a rearrangement of ALK in numerous tumor cells. To date, less than 17 cases of RCCs with ALK rearrangements are reported in children and adults. The prognosis remains uncertain but ALK rearrangement may be of potential value for target therapy with crizotinib.