Azathioprine-induced squamous cell carcinoma of the kidney.

Immunosuppressive therapy with azathioprine has been documented to cause squamous cell carcinoma (SCC) at various sites. We report possibly the first case of SCC of the kidney in a young male who received azathioprine for a long time. Discontinuation of azathioprine post-radical nephrectomy probably increased the patient's metastatic disease-free survival.