ĐẶC ĐIỂM MÔ BỆNH HỌC VÀ HÓA MÔ MIỄN DỊCH LYMPHÔM TẾ BÀO LỚN THOÁI SẢN VỚI ALK DƯƠNG TÍNH: NGHIÊN CỨU ĐA TRUNG TÂM VÀ HỒI CỨU Y VĂN

Abstract

Background: Anaplastic large cell lymphoma (ALCL) with ALK positivity is a distinct subtype of T-cell lymphoma, typically occurring in younger patients and characterized by heterogeneous histologic patterns and immunophenotypic profiles. Describing the histopathological and immunohistochemical features of ALK-positive ALCL contributes to diagnostic accuracy and therapeutic orientation. This study aimed to evaluate the histologic characteristics and immunophenotypic expression patterns of ALK-positive ALCL cases diagnosed at medical institutions in Ho Chi Minh City. Methods: A descriptive case series was conducted on patients diagnosed with ALK-positive ALCL between January 2020 and January 2025 at Ho Chi Minh City Oncology Hospital, Children’s Hospital No.1, and the Department of Embryology, Histology, and Pathology, University of Medicine and Pharmacy at Ho Chi Minh City. Results: A total of 38 cases were recorded. The mean age in the pediatric group (<16 years) was 8.2 ± 3.8 years, while in the adolescent/adult group (≥16 years) it was 27 years, with a male-to-female ratio of 1,2:1. Nodal involvement accounted for 68.4% and extranodal lesions for 31.6%. The histologic subtypes included classic (76.3%), lymphohistiocytic (13.2%), small-cell (7.9%), and other variants (2.6%). Regarding immunophenotype, ALK-1 staining showed both nuclear and cytoplasmic expression in 78.9% of cases and cytoplasmic-only expression in 21.1%. Positivity rates for T-cell lineage markers were CD2 (31.6%), CD3 (36.1%), CD5 (52.4%), CD45 (84.6%), and EMA (84.2%). EMA expression was predominantly focal (<25% of tumor cells) in 50% of cases. Conclusion: ALK-positive ALCL predominantly affects patients within the first three decades of life, with nodal involvement being most common and the classic subtype representing the majority of cases. ALK-1 expression is mainly nuclear and cytoplasmic. CD45 and EMA show high positivity rates and are useful adjunctive markers in diagnosis. Notably, EMA expression was mostly focal, differing from previous reports in the literature.