Extranodal diffuse large B-cell lymphoma presenting as a rapidly growing palatal mass in a patient with prior breast carcinoma.

A rapidly growing palatal swelling poses a diagnostic challenge due to its wide differential, including odontogenic, epithelial, salivary gland, mesenchymal and haematolymphoid pathologies. We report the case of an elderly female with a history of treated breast carcinoma who presented with a solitary palatal mass. Clinical and radiographic findings initially raised suspicion of a metastatic lesion because of the patient's previous malignancy, rapid lesion enlargement, firm fixation, bone erosion, sinus extension and cervical lymphadenopathy. However, histopathological examination and immunohistochemistry confirmed a diagnosis of extranodal diffuse large B-cell lymphoma rather than metastatic breast carcinoma, establishing it as a second primary malignancy. The patient was placed on palliative care due to her advanced age and compromised systemic condition but succumbed within 1 month. This case underscores the importance of including lymphoma in the differential diagnosis of rapidly enlarging oral swellings, even in patients with a remote history of solid-organ malignancy, and highlights the critical role of immunophenotyping in distinguishing lymphoid neoplasms from more common oral pathologies.