Axillary Reactive Lymphoid Hyperplasia, Likely Due to Unicentric Castleman Disease, and the Concurrent Presence of Orbital Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma: A Six-Year Follow-Up Study.

Castleman disease is a lymphadenopathy of unknown cause at a single site, which is designated as unicentric Castleman disease, or at multiple sites designated as multicentric Castleman disease. We present a patient who showed axillary reactive lymphoid hyperplasia, likely due to unicentric Castleman disease, and orbital extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) lymphoma in a six-year follow-up. A 76-year-old man had a painless left axillary mass for an unknown period and also left complete blepharoptosis with no other systemic symptoms. Suspected of lymphoma, iliac bone marrow biopsy showed no anomalous cells, and positron emission tomography demonstrated abnormal uptake at the left axilla and in the left superior anterior orbit. Incisional biopsy of the left axillary mass demonstrated hyperplastic lymphoid follicles with an atrophic germinal center and prominent small vessels in the follicular center, indicative of unicentric Castleman disease. One year later, annual follow-up positron emission tomography disclosed a high uptake site, next to the previously-identified cyst, in the pancreatic body. Trans-gastric fine needle pancreatic biopsy proved adenocarcinoma and he underwent subtotal stomach-preserving pancreaticoduodenectomy with jejunal anastomosis. He was well for six months after the surgery and thus, underwent resection of the left orbital lesion at 78 years old. The pathology of the orbital lesion showed ambiguous nodular structure with massive infiltration with CD20-positive medium-sized lymphoid cells which were κ monotype in immunoglobulin light chain restriction, indicative of MALT lymphoma. In the four-year period of the COVID-19 pandemic, he was healthy and followed with no treatment until the age of 82 years when he underwent radiation (46 Gy) to the left axillary lesion which did not regress. He then underwent eyelid levator muscle plication for left blepharoptosis since the left orbital lesion remained unpalpable. The six-year follow-up showed that concurrent and independent orbital MALT lymphoma and axillary reactive lymphoid hyperplasia, likely due to unicentric Castleman disease, were both stable. The present case illustrates how important it is to make pathological diagnoses in different anatomical lesions after the initial diagnosis of Castleman disease.