Mantle Cell Lymphoma With Major Salivary Gland Involvement Mimicking IgG4 ‐Related Disease/Mikulicz Disease—A Case Report

Abstract

ABSTRACT Background Mantle cell lymphoma (MCL) is an uncommon subtype of non‐Hodgkin lymphoma with distinct clinical, biological, and molecular features, most commonly affecting older males. Extranodal involvement is frequent, although salivary gland presentation is rare. We report an unusual case of MCL presenting with IgG4‐related disease like features in an Oral Medicine clinic. Case Report A 49‐year‐old female was referred following ultrasound findings suggestive of Sjögren's syndrome, showing multifocal hypoechoic areas within the bilateral parotid and submandibular glands. She reported nocturnal dry mouth but denied significant sicca symptoms. Clinical examination revealed persistent, non‐fluctuating bilateral salivary gland enlargement. Blood investigations demonstrated a negative ANA and ENA panel, mild cytopenias, low folate, low complement C4, and reduced IgM levels, with normal serum IgG4 subclass and sialometry. Despite a recent ultrasound, clinical and laboratory concerns prompted repeat imaging, which identified indeterminate cervical lymphadenopathy. Ultrasound‐guided biopsy confirmed mantle cell lymphoma. Conclusion This case highlights the importance of maintaining a high index of suspicion for lymphoma in patients presenting with IgG4‐related disease/Mikulicz disease features and persistent bilateral salivary gland enlargement, and to consider repeat imaging and tissue biopsy to avoid diagnostic delay and ensure timely management.