A 30 year-old woman who lived in the southern highlands of Tanzania presented with a 5-year history of progressive bilateral foot and ankle swelling. Mossy-like papillomata and block-shaped toes involving both feet were apparent, and the swelling had the consistency of a “water-bag” (Figure 1). The patient denied travel to Tanzania's coastal region. The symptoms of elephantiasis in the absence of exposure to areas where the mosquito vector for Wuchereria bancrofti is found make lymphatic filariasis unlikely and suggest podoconiosis.
Podoconiosis is known as “mossy-foot” because the papillomata have a moss-like appearance. It is caused by long-term barefoot exposure to volcanic soils high in silica. These soils are found in the highlands of tropical Africa, Central America, and northwest India.1 Seasonally heavy rains in these regions lead to soil erosion. Chronic, recurrent barefoot exposure to exposed silica leads to lymphatic obstruction resulting in ascending lymphedema.2
Podoconiosis is clinically distinguished from filarial elephantiasis. Unlike filarial elephantiasis, podoconiosis characteristically presents with block-shaped toes, mossy-like papillomata, and an ascending edema that stops at the knee without groin involvement (Figure 2). It is important to recognize that the presentation of podoconiosis can vary from the classic hard, nodular edema to a soft “water-bag” edema.1
Podoconiosis is preventable with consistent shoe wearing and good foot hygiene practices. Treatment includes use of compression bandages and elevation of the affected limbs.3 With time and proper treatment the edema and moss-like papillomata can diminish (Figure 2).
Davey G, Tekola F, Newport MJ, 2007. Podoconiosis: non-infectious geochemical elephantiasis. Trans R Soc Trop Med Hyg 101: 1175–1180.
Price EW, Henderson WJ, 1978. The elemental content of lymphatic tissues of barefooted people in Ethiopia, with reference to endemic elephantiasis of the lower legs. Trans R Soc Trop Med Hyg 72: 132–136.
Negussie H, Kassahun MM, Fegan G, Njuguna P, Enquselassie F, McKay A, Newport M, Lang T, Davey G, 2015. Podoconiosis treatment in northern Ethiopia (GoLBet): study protocol for a randomised controlled trial. Trials 16: 307.