Clinicopathological Correlates of CD56 Expression in Multiple Myeloma: Insights from a Cross-Sectional Study in an Indian Cohort

Abstract

Background: Multiple myeloma (MM) is a heterogeneous plasma cell neoplasm characterized by clonal proliferation of plasma cells within the bone marrow and associated end-organ damage. CD56, also known as neural cell adhesion molecule (NCAM), is aberrantly expressed in most cases of MM and has been implicated in plasma cell adhesion, bone marrow homing, and disease dissemination. The prognostic significance of CD56 expression in MM remains incompletely understood, particularly in Indian patients. Objectives: To evaluate the correlation between CD56 expression and clinicopathological as well as radiological parameters in patients with multiple myeloma. Methods: This prospective observational study was conducted in the Department of Pathology at Maharishi Markandeshwar Institute of Medical Sciences and Research, Mullana, Haryana, from May 2024 to October 2025. Thirty newly diagnosed patients fulfilling International Myeloma Working Group (IMWG) criteria for MM were included using convenient sampling. Bone marrow aspiration and biopsy specimens were subjected to histopathological examination and CD56 immunohistochemistry. Clinical details, biochemical parameters, International Staging System (ISS) stage, and radiological findings were recorded. Statistical analysis was performed using SPSS software. Categorical variables were analysed using Chi-square/Fisher exact test, while continuous variables were analysed using Student's t-test or Mann-Whitney U test depending on normality distribution. A p-value <0.05 was considered statistically significant. Results: Among 30 patients, 23 (76.7%) were CD56 positive and 7 (23.3%) were CD56 negative. The majority of patients belonged to the 61-70-year age group with male predominance. CD56-negative cases demonstrated relatively aggressive clinicopathological features including advanced ISS stage, elevated serum creatinine, increased B2-microglobulin, elevated LDH levels, anemia, and higher marrow plasma cell burden. Radiologically, extensive osteolytic lesions and vertebral involvement were more common in CD56-negative patients. Follow-up data available in 13 patients revealed comparatively poorer clinical response among CD56-negative cases. Conclusion: CD56 expression was observed in the majority of multiple myeloma cases. CD56-negative myeloma demonstrated aggressive clinicobiochemical and radiological characteristics, suggesting its potential utility as a prognostic biomarker. Evaluation of CD56 by immunohistochemistry may aid in risk stratification and prognostic assessment in resource-limited settings.