[The pathological diagnosis and differential diagnosis of hematopoietic cell tumors of ambiguous lineage].

Objective: To explore the key points of the pathological and differential diagnoses of extra-medullary masses of hematopoietic cell tumors of ambiguous lineage, and to discuss the possible solutions. Methods: Five hematopoietic cell tumors of ambiguous lineage cases were collected, including myeloid sarcoma, mixed phenotype acute leukemia, B/myeloid, T-lymphoblastic lymphoma combined with acute myeloid leukemia, acute undifferentiated leukemia with cutaneous MPDCP and early T-precursor cell acute lymphoblastic leukemia. The data including morphology, immunostaining, and flow cytometry analysis were collected, and we explored the problems and differential diagnosis in the diagnosis of hematopoietic cell tumors of ambiguous lineage. Results: The five cases showed that the accurate pathological diagnosis and classification of hematopoietic cell tumors of ambiguous lineage should be based on lineage-specific antigens. Moreover, tumor cells have the potential of multi-directional differentiation. In different sites or different periods, the differentiation of tumor cells may be different. Biopsy and detection of all related markers should be performed for the initial diagnosis, and the detection should be repeated when the condition of the patient changes. Combined application of multi-techniques, including morphology and flow cytometry analysis, is recommend for the diagnosis of hematopoietic cell tumors of ambiguous lineage, since the conventional morphology and immunophenotyping methods are limited. Conclusion: Hematopoietic cell tumors of ambiguous lineage are derived from hematopoietic stem cells with a potential of multi-differentiation. The differentiation of tumor cells is variable. We need to integrate cell morphology, flow cytometry, pathology, clinical data, and molecular genetics to make a comprehensive diagnosis.