[Cell morphological analysis of hepatosplenic T-cell lymphoma gamma-delta type]

Objective: To analyze the cell morphological features of hepatosplenic T-cell lymphoma (HSTCL) gamma-delta (γδ) type, differentiate from acute leukaemia (AL). Methods: This was a retrospective study. The clinical data of four cases of HSTCL γδ type who were treated in Hebei Yanda Ludaopei Hospital from 2009 to 2014 were collected. Their initial morphology diagnoses in other hospitals were all acute leukemia or myelodysplastic syndrome (MDS). Morphological analysis and cytochemical stains to their bone marrow (BM) aspiration and peripheral blood (PB) smears were completed when they had no response to previous chemotherapies, and the morphological reports were compared with results of immunophenotyping, chromosome, and T cell receptor (TCR) gene rearrangement. Results: The percentages of malignant cells in four patients' BM aspirations were 7.6%-40.0%, and in two patients' PB was 9% and 10%, respectively. The morphology of four cases had a very high similarity in Wright's stain. Predominantly medium-sized cells were seen, with rich cytoplasm and frequently one big conspicuous nucleolus. The malignant cells resembled blasts, especially monoblasts, but with coarse granular chromatin, more compact than that in monoblasts. When comparing to malignant myeloblast and lymphoblasts, HSTCL cells were larger and more irregular in cell shape, with more abundant cytoplasm and prominent nuclear irregularity. The cytochemistric stain played an important role in differential diagnosis. HSTCL malignant cells showed non-specific esterase (NSE) negative or focal punctate activity which couldn't be inhibited by sodium fluoride. Periodic acid-Schiff (PAS) stain was negative or positive with a form of coarse granules. The myeloperioxdase (MPO) stain was negative. Conclusion: Malignant cells of HSTCL γδ type have very distinct morphological features of mature lymphocytic neoplasm. The quality of Wright's stain, being short of complete cytochemical stains, lacking of awareness of this disease, and acute leukemia or MDS like appearance in some cases, result in the possibility of diagnostic error as malignant blast, and probably are main causes of misdiagnosis of HSTCL γδ type.