PMC10083421_01
Bone marrow smear: active proliferation. The positive rate of periodic acid-Schiff staining was 75%. Some heteromorphic lymphocytes were small to moderate in size with mature aggregated chromatin, scant cytoplasm, and irregular nuclear contours. The smear suggested lymphoproliferative diseases.
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Bone marrow smear showed an increase in mature heteromorphic lymphocytes ( Figure 1 ), suggesting a chronic lymphoproliferative disease.
(A) Immunophenotype of bone marrow by flow cytometry. Method: sample staining (lyse and wash) by fluorescent-labeled monoclonal antibody was performed, a BD FACSCanto II flow cytometer was used, and the data were analyzed using BD FACSDiva software. Result: P2 (red) was lymphocytes, accounting for 38.5% of non-erythrocytes in the sample. B cells accounted for 85% of lymphocytes and mainly expressed CD19, CD20, CD22, CD5, CD23, and CD200 but did not express CD10, FMC7, and sIg (surface immunoglobulin), with lambda light-chain restriction. The immunophenotype of B cells was abnormal phenotype. (B) Immunohistochemistry and histopathology of lymph node biopsy. The neoplastic follicles were closely packed, showing an almost back-to-back pattern, and lacked mantle zones (low power, x40). Most of the cells in the field were centrocytes (high power, x400). Immunostaining showed that the tumor cells were positive for CD20, CD10, BCL-6, and BCL-2 and negative for CD3, CD5, and CD23, and the Ki-67 index was about 20%. CD3 and CD5 were positive for background T cells, and CD23 was positive for follicular dendritic cells, while follicular lymphoma cells did not express CD5 and CD23.
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The immunophenotype of bone marrow by flow cytometric analysis ( Figure 2A ) was an abnormal B-cell phenotype: CD19+CD20+CD5+CD23+CD200+CD22+CD10-FMC7-sIg-. Biopsy of the left inguinal lymph node was scheduled (see pathological details in  Figure 2B ), and the patient was finally diagnosed with follicular lymphoma (FL) in the leukemic phase.
Results of positron emission tomography (PET)-CT. PET-CT scan revealed multiple lymphadenopathy (SUVmax 5.0) in the bilateral cervical, bilateral axillary, mediastinal, retroperitoneal, supra-mesenteric, iliac vessel, and bilateral inguinal region, and the maximum cross section of the lymph node mass was 10.9 cm x 10.2 cm. Liver (SUVmax 3.2) and spleen (SUVmax 3.0) were significantly enlarged. Metabolism of central and peripheral bone marrow was diffusely increased, with SUVmax of 3.6.
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PET-CT scan revealed multiple (cervical, axillary, inguinal, retroperitoneal, etc.) lymphadenopathy (maximum cross section: 10.9 cm x 10.2 cm) and obvious hepatosplenomegaly, with a maximum SUV of 5.0 ( Figure 3 ).