Precursor T-lymphoblastic lymphoma: Speedy diagnosis in FNA and effusion cytology by morphology, immunochemistry, and flow cytometry.

BACKGROUND Precursor T-lymphoblastic lymphoma (T-LBL) is a rare lymphoma presenting clinically in children and adolescents with a rapidly enlarging mediastinal mass, dyspnea, and cervical lymphadenopathy requiring quick diagnosis. The objective of the current study was to report on the spectrum of cytomorphology and flow cytometric immunophenotyping (FCI). METHODS The clinical profile, cytomorphological features, FCI, and cell block immunocytochemistry (CB-ICC) of all cases of T-LBL diagnosed from 2011 through 2013 were reviewed. RESULTS Fifteen cases of precursor T-LBL (10 fine-needle aspiration samples and 5 pleural/pericardial fluid samples) were evaluated. Smears demonstrated dispersed lymphoblasts, with a high nuclear:cytoplasmic ratio and scanty basophilic cytoplasm. Nuclei demonstrated notches, clefts, and indentations. The chromatin was condensed in small and intermediate-sized blasts and dispersed in larger blasts. Nucleoli were present only in the larger blasts. Hand mirror-shaped cells and mitoses were variable. With regard to immunophenotyping, flow cytometry demonstrated positivity for CD2 (15 of 15 cases), surface CD3 (14 of 15 cases), cytoplasmic CD3 (15 of 15 cases), terminal deoxynucleotidyl transferase (TdT) (8 of 15 cases), CD5 (13 of 15 cases), CD10 (7 of 15 cases), and human leukocyte antigen-D related (HLA-DR) (1 of 15 cases). Dual CD4/CD8 positivity was observed in all cases forming a tight cluster, which is consistent with the cortical T-LBL subtype. CB-ICC demonstrated a uniform CD3-positive/TdT-positive/CD20-negative phenotype. In 7 cases in which TdT was negative by flow cytometry, CB-ICC was positive. CONCLUSIONS Combining cytomorphology and FCI enables the accurate and rapid diagnosis of T-LBL on fine-needle aspiration and effusion cytology specimens, thereby obviating the need for a biopsy. Cancer (Cancer Cytopathol) 2015;123:557–565. © 2015 American Cancer Society.