To classify NHL as a bone primary disease, it is important to exclude any other evidence of visceral or lymphatic involvement and no other site lesion at least 6 months after diagnosis. Oral lymphomas account for 2.5% of all cases of lymphomas, and when there is involvement of soft tissues, salivary gland, cheeks, paranasal sinuses, and gingiva are the most affected sites [1, 10]. Bone involvement of the jaws is rare and occurs more frequently in the maxilla than in the mandible [1, 4, 6, 10]. Primary NHL of the mandible represents 0.6% of all NHL, 5% of all bone NHL, and 8% of all mandibular tumors [1, 7, 12]. It presents predilection for more men, occurring more frequently in the sixth decade of life [6, 7]. The present case affected exclusively bones (mandible and clavicle) in a 56-YO man.
Mandible lymphomas may be misdiagnosed as an odontogenic infection or tumor. Consequently, delay in the diagnosis is commonly observed, with a mean time of 2 to 3 months [1, 4, 5, 8, 10,11,12]. The most frequent clinical manifestations are localized bony growth, dental mobility, pathological fracture, pain and neurological disturbance [1, 2, 6, 7, 10, 12]. In the current case, the patient had a history of tooth extraction 4 months previous to the diagnosis, with pain appearing as the chief complain. Radiographic examination usually shows diffuse bone destruction, alveolar bone resorption, periodontal disease, and loss of cortical definition or enlargement of the mandibular canal [1,2,3, 6, 7, 10, 12]. In this case, an extensive osteolytic lesion and pathological condyle fracture were the main findings. Furthermore, loss of the definition of the mandibular canal was also observed. All features are strongly suggestive of a malignant neoplasm.
Treatment for jaw lymphomas usually consists of a combination of chemotherapy and radiation therapy. The prognosis of these lesions is favorable when localized diseases. However, maxillary lymphoma has a higher rate of recurrence when compared to other sites of involvement [3]. The present patient was submitted to chemotherapy and radiotherapy (only in mandibular fields), with no disease relapse after 6 years.
In conclusion, radiolucent lesions with ill-defined margins associated with pain are important features of a malignant neoplasm, including DLBCL. Thus, the radiologist should keep in mind that, although DLBCL is rare, it may occur in the mandible. Additionally, despite of rarity, the DLBCL should be included in the differential diagnosis of lesions with such features.