Important tumor types with low or absent Napsin A immunostaining included various squamous cell carcinomas (e.g. lung, larynx, esophagus), different subtypes of breast carcinomas, adenocarcinomas of the prostate, non-invasive papillary urothelial carcinomas, various soft tissue tumors, and bone tumors. The gene discussed is NAPSA; the disease is squamous cell carcinoma.