Hyperreactive malarious splenomegaly (tropical splenomegaly syndrome).

Hyperreactive malarious splenomegaly (HMS), formerly known as tropical splenomegaly syndrome (TSS), was recognized some 20 years ago as an entity distinct from the splenic enlargement resulting directly from malarial parasitaemia. Its basis appears to be a disturbance in the T-lymphocyte control of the humoral response to recurrent malaria, possibly linked to particular HLA Class II antigens. Gross overproduction of IgM antibodies leads to the formation of high molecular weight immune complexes, persistent gross splenomegaly recurrent episodes of profound anaemia and increased susceptibility to infections. Those with gross disease experience a high mortality, which constitutes a major public health problem in communities where the syndrome affects a majority of adults.