Objective: Four cases of nasopharyngeal granulomatous inflammation after radiotherapy for undifferentiated carcinoma were analyzed for tuberculosis, and the histologic features were compared.
Study design and setting: We conducted a retrospective study with analysis of tuberculosis by Ziehl Neelsen staining and polymerase chain reaction analysis for Mycobacterium tuberculosis DNA on histologic materials.
Results: Three patients had previous nasopharyngeal undifferentiated carcinoma, one had previous metastatic undifferentiated carcinoma to cervical lymph nodes, and all patients received similar radiotherapy regimen. The light microscopic features were similar with epithelioid histiocytes and granulomas with Langhan's giant cells. In 3 cases, acid-fast bacilli were identified by Ziehl Neelsen stain, and 1 was negative. The results of 2 cases were confirmed by polymerase chain reaction analysis for Myocbacterium tuberculosis DNA.
Conclusion: Granulomatous reaction after radiotherapy of nasopharyngeal undifferentiated carcinoma can be caused by tuberculosis.
Significance: Diligent search for organisms in postirradiation granulomatous inflammation is warranted to avoid missing an occult tuberculosis infection.