In this case report, a 68-year-old woman, with known insulin-dependent diabetes and myelomatosis, presented with ear pain in her right ear. Otomicroscopy showed exposed bone in the external auditory canal. The patient was examined with wound swab, biopsies, MRI and PET-CT scans to rule out necrotizing external otitis, cholesteatoma and malignancy. Later, the patient's bisphosphonate treatment for myelomatosis was suspected, because osteonecrosis of the external auditory canal is a rare side effect to this treatment. The bone lesion improved after local debridement and cessation of the bisphosphonate treatment.