01 April 2026
: Case report 
A 64-Year-Old Man Presenting With Diplopia and Right Orbital Swelling Due to Mucosa-Associated Lymphoid Tissue Lymphoma
Challenging differential diagnosis, Rare disease
Lubna M. Altamimi ABDEF 1, Farjah H. Algahtani
ABDEF 1,2*, Mohammed Ghannam Alharbi ABD 1,2,3, Fadi S. Alakeel ABE 1,4, Beshayer A. Alhentti ABD 1,4
DOI: 10.12659/AJCR.951426
Am J Case Rep 2026; 27:e951426
Figure 5 Immunohistochemical stains showing negative markers supporting the diagnosis of extranodal marginal lymphoma (MALT type). (A) CD10 immunostain was negative, excluding follicular lymphoma (×200). (B) BCL6 immunostain was negative, further arguing against follicular lymphoma (×200). (C) CD5 highlighted background T cells without abnormal expression in neoplastic B cells (×200), helping exclude mantle cell lymphoma and chronic lymphocytic leukemia. (D) MUM1 immunostain was negative, supporting a non–activated B-cell phenotype (×200). (E) Cyclin D1 immunostain was negative, excluding mantle cell lymphoma (×200). MALT – mucosa-associated lymphoid tissue.