A 78-year-old male, undergoing acalabrutinib treatment for chronic lymphocytic leukemia, presented with a persistent cutaneous ulcer on his left leg. Initial empirical antibiotic therapy failed. Histopathological examination revealed granulomatous inflammation, and subsequent culture of a biopsy specimen identified *Mycobacterium abscessus*. The patient was diagnosed with cutaneous atypical mycobacteriosis. Treatment involved surgical debridement and a combination of amikacin, imipenem, and clarithromycin, leading to significant improvement. This case highlights the importance of considering atypical mycobacterial infections in immunocompromised patients with non-healing skin lesions, especially those on targeted therapies like acalabrutinib.
Key note: Atypical mycobacterial infections should be considered in immunocompromised patients on targeted therapies presenting with non-healing cutaneous ulcers.