NAPSA and papillary renal cell carcinoma: Napsin A is mainly expressed in the cytoplasm of type II pneumocytes, intra-alveolar macrophages, proximal and convoluted renal tubules, and pancreatic acini and ducts [4, 5] as well as adenocarcinomas of the lung, papillary renal cell carcinomas, and ovarian clear cell carcinomas [1, 6, 7].