Learning Objectives: To highlight the need to be vigilant for unusual diagnoses that may mimic common otological conditions.

Introduction: To report a case of temporal bone B cell lymphoma.

Methods: Review of inpatient case notes of patient with atypical presentation of lymphoma.

Results: Temporal bone involvement by malignancies, primary or secondary, is rare. Diagnosis is frequently delayed as the symptoms mimic more common otological conditions like otitis external or media. Involvement of cranial nerves or cochleovestibular system may occur in advanced cases. More commonly, the bone involvement is due to direct extension of locally invasive squamous or adenocarcinomas of ear. Primary B cell bone lymphomas are also a rare entity and the presentation is usually with pain, swelling or fracture of involved bones. Mastoiditis due to destruction of underlying temporal bone by malignant lymphoma has only been reported in about 20 cases in the literature. We describe a case of primary B cell lymphoma presenting with radiological evidence of mastoiditis, skull base osteomyelitis and sigmoid sinus thrombosis. Patient was initially treated with broad-spectrum antimicrobials and it was not until development of facial palsy that a decision of mastoid exploration was made. Histopathological examination confirmed infiltration of temporal bone by malignant B cells. Staging studies including a diagnostic bone marrow biopsy diagnosed the patient with stage IV primary diffuse large B cell lymphoma of the bone. Treatment was initiated with multi-agent chemotherapy with good results.

Conclusion: Atypical presentation of otological signs and symptoms refractory to medical management requires a thorough evaluation and consideration of uncommon differentials. A high index of suspicion towards temporal bone malignancies may be helpful in timely diagnosis.