Invasive squamous cell carcinoma of the mandible presenting as a chronic osteomyelitis: report of a case. A case of invasive squamous cell carcinoma of the mandible initially thought to be chronic osteomyelitis is reviewed. Discussion of the origin of the tumor and several imaging techniques used for differentiating maxillofacial infection from neoplasm are discussed. The difficulty of diagnosis of chronic painful maxillofacial lesions illustrates the need for a high degree of suspicion concerning any inflammatory lesion not responding to appropriate therapy. Accurate diagnosis and treatment of such lesions most often necessitates microscopic examination. 