Tropical splenomegaly in a migrant-in-transit crossing the Darien gap, Panamá: A probable case of hyper-reactive malarial splenomegaly

Hyper-reactive malarial splenomegaly (HMS), or tropical splenomegaly syndrome, is a severe complication of chronic and recurrent infections caused by Plasmodium spp. This condition typically results in splenomegaly greater than or equal to 10 cm and a constellation of laboratory findings, including the absence of identifiable parasites in peripheral blood smears. However, patients with HMS demonstrate serological or molecular evidence of infection. Despite being a familiar entity in malaria holoendemic countries in Africa, and regions of Papua New Guinea, the pathophysiology, natural history, and treatment of the syndrome remains to be fully elucidated. Herein, we describe a highly suggestive case of HMS in a Senegalese patient migrating northbound to reach the U.S.-Mexico border and for whom we provided medical care during his crossing of the Darien Gap in Panama. We also reviewed the literature on diagnosing and treating HMS in-depth.