Marked IgE elevation and eosinophilia in a COPD patient ultimately diagnosed with mycobacterium intracellulare pulmonary disease.

BACKGROUND

Marked eosinophilia and elevated total IgE levels usually suggest allergic, fungal, or parasitic diseases. Non-tuberculous mycobacterial (NTM) infections are rarely considered in these cases.

CASE PRESENTATION: A 65-year-old man with COPD and emphysema was referred for persistent eosinophilia (550-630/µL) and markedly elevated total IgE (2912 IU/mL). Evaluation for allergic diseases, including allergic bronchopulmonary aspergillosis, was negative. Chest computed tomography showed severe emphysema with patchy pulmonary consolidations. Three separate sputum cultures grew Mycobacterium intracellulare.

CONCLUSION

This case highlights that pulmonary Mycobacterium intracellulare infection may rarely present with eosinophilia and markedly elevated IgE levels, mimicking allergic disease. NTM infection should be considered in the differential diagnosis of unexplained eosinophilia and elevated IgE, particularly in patients with structural lung disease.