Nasal infection caused by Mycobacterium avium is rare and is a diagnostic challenge due to the non-specific symptoms and absence of pathognomonic signs.

We report the case of a 72-year-old patient with chronic rhinitis persisting for 4years and refractory to conventional treatments. ENT examination revealed irregular nasal mucosa with an inflammatory nasopharyngeal polyp. Histological analysis showed epithelioid granuloma, and Ziehl-Neelsen staining highlighted acid-fast bacilli. Mycobacterial culture confirmed M. avium infection. Treatment with rifampin, azithromycin and ethambutol led to significant clinical improvement, with resolution of local inflammation.

Nasal infection by M. avium is exceptional, with only a few cases reported in the literature. Diagnosis relies on histological examination and mycobacterial culture. Treatment combines surgical resection of the polypoid tumor and prolonged antibiotic therapy.

M. avium infection should be considered in cases of atypical chronic rhinitis resistant to treatment. Thorough microbiological evaluation is essential for accurate diagnosis and appropriate management.