Sandbox: T cell

Adult T‐cell leukaemia/lymphoma (ATLL) is a mature T‐cell neoplasm of post‐thymic lymphocytes Etiologically linked to the human T‐cell lymphotropic virus, HTLV‐I, HTLV‐I serology is a mandatory investigation The disease manifests in 75% of cases with leukaemia and in the remaining as a pure lymphomatous form

anaemia and thrombocytopenia is variable Neutrophilia and eosinophilia Present hypercalcaemia

Diffuse infiltration of the lymph node leading expansion of the paracortical area Infiltration of the dermis skin infiltration, epidermotropism present and Pautrier's microabcesses

antibodies to HTLV‐I are demonstrable

+3, +7, +21, monosomy X,deletion of chromosome Y anf chromosomes 6 and 14q; 14q11 and break points e TCR‐alpha and ‐delta chain genes TCRA and TCRD 14q32 of TCL1 mutations of tumour‐suppressor genes CDKN2A (p16), CDKN2B (p15) and TP53 (p53)

pleomorphic, a medium size lymphocyte conndensed chromatin convoluted or polylobated nucleus nucleoli are not visibl cytoplasm agranular “flower cell”

CD4 positive CD8 positive CD2 and CD5 positive CD7 negativ CD3 and T‐cell receptor (TCR)‐β may be down‐regulated