Odontogenic Maxillary Sinusitis With Sequestrum-Like Bone Formation Mimicking Fungal Sinusitis: A Case Report

Calcified materials in an opacified maxillary sinus often suggest fungal sinusitis, particularly aspergillosis. However, odontogenic maxillary sinusitis may rarely be associated with a bone-like calcified mass, creating diagnostic difficulty. We report a case of chronic odontogenic maxillary sinusitis with sequestrum-like bone formation that mimicked fungal sinusitis. An 88-year-old man was referred for mobility and occlusal pain of the maxillary left first molar. He had no nasal obstruction, rhinorrhea, headache, facial pain, or history of maxillary sinus surgery. Intraoral examination showed marked periodontal destruction, root exposure, tooth mobility, and percussion and occlusal pain. A hard structure was palpable through the periodontal pocket. Panoramic radiography showed increased opacity of the left maxillary sinus and a well-defined, horseshoe-shaped, bone-like radiopaque mass near the root apex. Computed tomography revealed a capsular calcified structure adjacent to the root apex within soft tissue occupying the left maxillary sinus, with extension toward the ethmoid sinus and thickening of the sinus wall. Fungal maxillary sinusitis was considered in the radiographic differential diagnosis. Under local anesthesia, extraction of the affected tooth, removal of the calcified mass, and maxillary sinus fenestration were performed. The mass, identified through the extraction socket, was not adherent to the tooth and was easily separated from the surrounding tissue. No fungal organisms, including Aspergillus species, were identified on histopathological examination. The excised specimen was a hard bone-like mass measuring approximately 20 × 15 mm. Histopathological examination revealed a sequestrum with areas suggestive of pre-existing lamellar bone and newly formed, incompletely mineralized bone. At one-year follow-up, maxillary sinus mucosal thickening had improved. This case illustrates that odontogenic maxillary sinusitis may be associated with a bone-like calcified mass and may radiographically mimic fungal sinusitis. When surgical treatment is clinically indicated, histopathological examination of the removed lesion can help establish a definitive diagnosis.