RESUMO
Non-Hodgkin lymphomas (NHLs) are malignant neoplasms of the lymphatic system, typically occurring in the fifth through seventh decades of life. Tumors develop from abnormal lymphocyte proliferation and accumulation. Although a majority of NHLs occur in nodal regions, 40% of cases appear in extranodal sites involving the stomach, spleen, Waldeyer's ring, central nervous system, lung, skin, and bone. Extranodal NHL presents a diagnostic challenge because it may mimic endodontic disease when occurring in intraosseous and soft tissue sites. This case report presents misdiagnosis of a diffuse large B-cell lymphoma (DLBCL) of the anterior maxilla in a 72-year-old man with a history of Waldenstrom's macroglobulinemia, where the lesion was thought to be associated with a necrotic pulp and a chronic apical abscess on tooth #7. Clinical findings of a facial sinus tract, a nonresponsive pulp, large periapical radiolucency, and history of trauma were in support of this diagnosis for tooth #7. On encountering vital pulpal tissues during cavity access of tooth #7, a cone-beam computed tomography scan and lesion biopsy were obtained. Through immunohistochemistry and histologic analysis, a diagnosis of DLBCL was made. During evaluation of lesions with suspected endodontic etiology, the clinician should consider all factors of the patient's health history, hereditary risk, and comprehensive clinical testing to attain a differential diagnosis. A nonodontogenic etiology of disease should always be considered unless ruled out otherwise. Atypical presentation or testing may prompt the need for biopsy and interspecialty assessment.