[Clinicopathological features and prognosis of marginal zone lymphoma with aberrant CD10 expression]

Objective: To investigate the associations of aberrant CD10 expression with clinicopathological features and prognosis of marginal zone lymphoma (MZL). Methods: A retrospective analysis was conducted on 13 cases of MZL with aberrant CD10 expression, diagnosed at the First Affiliated Hospital of Zhengzhou University, Zhengzhou, China between April 2015 and July 2024. Clinical features, morphological findings, immunohistochemical profiles, and molecular testing results were analyzed. The patients were also assessed via telephone follow-up. Results: There were 7 male and 6 female patients, aged 55.0 (51.5,70.0) years on average. Subtypes comprised 10 extranodal MZLs of mucosa-associated lymphoid tissue (EMZL), 2 splenic MZLs (SMZL), and 1 nodal MZL (NMZL). Histologically, tumor cells exhibited diffuse (10 cases) or nodular (3 cases) growth patterns. In all three nodular cases, the proportion of CD10-positive cells was 50% or higher. Under high-power magnification, most cases (12 of 13 cases) were dominated by proliferation of small lymphocyte-like cells. One case was characterized by a mixed proliferation of monocytoid B cells and small lymphocyte-like cells. Histological features included follicular colonization (8 cases) and lymphoepithelial lesions (2 gastric cases and 2 pulmonary cases). Plasma cell differentiation was observed in 10 cases (9 EMZLs and 1 NMZL) and scattered interstitial hemosiderin deposits were seen in 7 cases (5 EMZLs and 2 SMZLs). Immunophenotypically, tumor cells expressed CD20 (13/13 cases), CD79α (11/13 cases), and bcl-2 (12/13 cases), whereas CD3, bcl-6, and Cyclin D1 were all negative. All 13 cases were positive for CD10, with the proportion of positive cells ranging from 5% to 80%. Among them, 6 cases exhibited CD10 positivity in less than 50% of tumor cells, and 7 cases showed CD10 positivity in 50% or more of tumor cells. The Ki-67 proliferation index ranged from approximately 5% to 30%. Molecular testing revealed monoclonal immunoglobulin gene rearrangement in 2 cases, MALT-1 gene break in one EMZL case, and no bcl-2 gene break in 10 MZL cases. Follow-up durations ranged from 11 to 122 months. Favorable post-treatment outcomes were observed in all 13 patients. Conclusions: MZL with aberrant CD10 expression is a rare variant, demonstrating clinicopathological features similar to conventional MZL and a generally favorable prognosis. Its immunophenotype may mimic other CD10-positive small B-cell lymphomas, particularly follicular lymphoma. An accurate diagnosis appears to require integration of histologic, immunophenotypic, and molecular findings to avoid misdiagnosis.