Occult MALT lymphoma masquerading as benign cysts in Sjögren's syndrome: A case report of diagnostic dilemma.

Abstract

Introduction: Sjögren's syndrome (SS) significantly elevates the risk of salivary gland lymphoma, primarily mucosa-associated lymphoid tissue (MALT) type, arising within chronic lymphoepithelial sialadenitis (LESA). Benign lymphoepithelial cysts (BLECs), common in SS, can radiologically mimic malignancy, posing diagnostic challenges when occult lymphoma develops.

Case presentation: A 53-year-old woman with established SS developed progressive bilateral parotid enlargement over years. Initial ultrasonography and CT imaging revealed bilateral septated cysts, ductal calculi, and heterogeneous gland architecture, interpreted as benign inflammatory disease or sialolithiasis. Subtotal parotidectomy performed for cosmetic concerns on the larger side yielded histopathology confirming MALT lymphoma arising within LESA and BLECs.

Discussion: This case underscores the diagnostic dilemma of cystic parotid lesions in SS, where benign-appearing BLECs can harbor or be adjacent to occult MALT lymphoma. The malignant transformation highlights the inherent risk within chronic LESA. Imaging features of BLECs and cystic lymphoma often overlap; key discriminators like restricted diffusion on MRI warrant attention. Fine-needle aspiration has limitations, necessitating histopathological evaluation of tissue for definitive diagnosis, especially with persistent gland enlargement.

Conclusion: Persistent or progressive parotid enlargement in SS, even with cystic features suggestive of benign disease, necessitates a high index of suspicion for occult lymphoma. Histopathological verification remains paramount for accurate diagnosis and timely intervention, emphasizing the critical need for integrated clinical, radiological, and pathological assessment in these high-risk patients.