ABSTRACT
BACKGROUND: Mucosa associated lymphoid tissue (MALT) lymphoma of the orbit is rare, often indolent, but can recur, and spread to extra-nodal sites. Pleural and retroperitoneum recurrences of MALT lymphoma are rare. CASE: A 65-year-old man was referred to our hospital due to right pleural effusion and difficulty in breathing. He had a medical history of having undergone surgery for MALT lymphoma of the left orbit. A chest computed tomography (CT) scan showed right pleural thickness, pleural effusion, and a retroperitoneal mass, spreading from the muscular layer to the subcutaneous layer. The thickened pleural lesion was surgically biopsied and diagnosed as a recurrence of MALT lymphoma. CONCLUSION: Pleural effusion should be carefully examined and monitored for the possibility of recurrence in MALT lymphoma patients.