The histopathology of adult T-cell lymphoma/leukaemia in blacks from the Caribbean.

The histopathological features of seven cases of adult T-cell lymphoma/leukaemia (ATLL), all occurring in black patients from the Caribbean, are described. Lymph node infiltrates are initially restricted to the paracortical zone, with preservation of the nodal shape and subcapsular sinus, and accompanied by a proliferation of post-capillary venules. Cytologically, a range of cell types is present, from smaller cells with irregularly shaped nuclei and clumped nuclear chromatin to larger cells with dispersed chromatin and more prominent nucleoli, apparently corresponding to the stages of peripheral T-lymphocyte transformation. The proportion of each cell type present varies from case to case, as do the numbers of admixed eosinophils, plasma cells and interdigitating reticulum cells. These histological appearances are very similar to those of the pleomorphic T-cell lymphoma described in Japan, which also shows many clinical similarities, including a high incidence of complicating hypercalcaemia. There is a strong association in both Japanese and Caribbean patients with a recently described human retrovirus, HTLV, which occurs endemically in those areas where the disease clusters. Morphological similarities exist between ATLL and other peripheral T-cell lymphomata and leukaemias. These are illustrated by one notable 'linking' case. However, while related to other disorders of mature T-lymphocytes, ATLL nevertheless represents an identifiably separate clinicopathological entity.