Department of Hematology, Zhongnan Hospital of Wuhan University, 169 Donghu Road, Wuchang District, Wuhan, Hubei, 430071, People's Republic of China.
Department of Pathology, Zhongnan Hospital of Wuhan University, Wuhan University Center for Pathology and Molecular Diagnostics, 169 Donghu Road, Wuchang District, Wuhan, 430071, People's Republic of China.
Diagn Pathol. 2020 Apr 3;15(1):31. doi: 10.1186/s13000-020-00932-0.
Reverse Variant of Follicular Lymphoma (RVFL) is one of the rare morphological variants of FL, characterized by dark staining small centrocytes in the center and pale staining large centroblasts at the periphery of the neoplastic follicles. Only rare cases of RVFL have been described to date. The histological appearance of this little known variant of FL may be misinterpreted if pathologists are unaware of its existence. The main purpose of this study is to draw pathologists' attention to such an uncommon growth pattern of FL so that this variant can be correctly recognized and the clinical significance further studied in the future.
Four cases of FL with unusual morphologic features were evaluated for the expression pattern of CD20, CD10, BCL6, BCL2, CD21, CD23, CD3, CD5, Cyclin D1, IgD and Ki67 by immunohistochemistry. Fluorescence in situ hybridization (FISH) with break-apart probes was performed to detect BCL2 gene rearrangement.
All four cases showed distinctive morphologic pattern of RVFL; in addition, each also exemplified unique morphological features. Immunohistochemical stains confirmed the cells in both the central areas and the peripheral cuffs had the same immunophenotypic profiles, contrasting to the FL with marginal zone differentiation in which only the center of the nodules showed expression of CD10. FISH demonstrated BCL2 gene rearrangement in all cases.
The growth pattern of this rare FL variant may mimic FL with marginal-zone differentiation and other entities including but not limited to marginal zone lymphoma (MZL), progressive transformation of germinal centers (PTGC) and nodular lymphocyte predominant Hodgkin lymphoma (NLPHL). Pathologists should be familiar with this unusual morphological variant to avoid diagnostic pitfalls.
滤泡淋巴瘤反向变异型（RVFL）是 FL 的罕见形态学变异型之一，其特征是肿瘤滤泡中心的暗染小中心细胞和周边的淡染大中心母细胞。迄今为止，仅描述了少数 RVFL 病例。如果病理学家不知道这种 FL 的罕见变异型的存在，其组织学表现可能会被误解。本研究的主要目的是引起病理学家对 FL 这种罕见生长模式的注意，以便正确识别这种变异型，并在未来进一步研究其临床意义。
对 4 例具有不典型形态特征的 FL 病例进行 CD20、CD10、BCL6、BCL2、CD21、CD23、CD3、CD5、Cyclin D1、IgD 和 Ki67 的免疫组化表达模式评估。采用断裂探针荧光原位杂交（FISH）检测 BCL2 基因重排。
所有 4 例均显示出独特的 RVFL 形态模式；此外，每例还表现出独特的形态特征。免疫组化染色证实，中央区域和外周袖套中的细胞具有相同的免疫表型特征，与具有边缘区分化的 FL 不同，只有结节的中心显示 CD10 表达。所有病例均显示 BCL2 基因重排。
这种罕见的 FL 变异型的生长模式可能类似于具有边缘区分化的 FL 和其他实体，包括但不限于边缘区淋巴瘤（MZL）、生发中心进行性转化（PTGC）和结节性淋巴细胞为主型霍奇金淋巴瘤（NLPHL）。病理学家应熟悉这种不寻常的形态学变异型，以避免诊断陷阱。
