Granulomatous nasopharyngeal carcinoma: with emphasis on difficulty in diagnosis and favorable outcome.

Nasopharyngeal carcinoma (NPC) can provoke a local granulomatous reaction which may cause diagnostic difficulty. To further elucidate this possible diagnostic pitfall, 47 cases who were initially diagnosed as tuberculosis or granulomatous inflammation were reexamined; 7 cases (15%) were found to have NPC. In a routine histological stain, residual malignant tumor cells could be identified in 2 cases. In the remaining 5 cases, malignant tumor cells could only be accurately identified after careful examination. Immunohistochemical staining for keratin easily demonstrated the residual tumor cells engulfed in a granulomatous lesion in all 7 cases. This finding suggests that an immunohistochemical stain for keratin is useful and should be performed for any nasopharyngeal biopsy showing granulomatous lesion with suspicion of malignancy, particularly in countries where NPC is prevalent. The overall 5-year survival rate among these NPC patients was 83%, a most favorable outcome, which suggests that a granulomatous reaction may reflect a favorable local host, and a cell-mediated immune response.