Objective: To discuss the challenges in diagnosis and appropriate management of critical underlying pathoses if a patient presents with signs and symptoms indicative of different conditions that may coexist. Summary: This case features clinical and radiographic challenges in reaching a diagnosis in a middle-aged man undergoing bisphosphonate therapy for multiple myeloma. The patient had history of bisphosphonaterelated osteonecrosis of the jaw (BRONJ) in the mandible. The patient presented with pain and swelling in the anterior maxilla, associated with paresthesia of upper lip. The radiographic features were suggestive of BRONJ and invasive fungal sinusitis. MRI appearance was suggestive of malignant involvement by plasmacytoma or lymphoma. Although biopsy is usually not advocated in bisphosphonate-affected jaws, it was advised in this case and was positive for multiple myeloma. Vigilance is required to correlate clinical and radiologic findings and further investigations must be considered if malignancy is suspected. Schlagwörter: bisphosphonate-related osteonecrosis of jaw, invasive fungal sinusitis, multiple myeloma