Podoconiosis, also known as nonfilarial elephantiasis,[1] is a disease of the lymphatic vessels of the lower extremities that is caused by chronic exposure to irritant soils.

It is the second most common cause of tropical lymphedema after lymphatic filariasis,[2] and it is characterized by prominent swelling of the lower extremities, which leads to disfigurement and disability.

Early on, symptoms may include itching, tingling, widening of the forefoot, and swelling which then progress to soft edema, skin fibrosis, papillomatosis, and nodule formation resembling moss, giving rise to the disease's alternate name of "mossy foot" in some regions of the world.

[8] According to the World Health Organization "Evidence suggests that podoconiosis is the result of a genetically determined abnormal inflammatory reaction to mineral particles in irritant red clay soils derived from volcanic deposits".

[9] The pathophysiology of podoconiosis is a combination of genetic susceptibility, possibly through associations with HLA-DQA1, HLA-DQB1, and HLA-DRB1 variants, and a cumulative exposure to irritant soil.

[citation needed] Lepromatous lymphedema can also mimic podoconiosis clinically, but the former will have a loss of sensation in the toes and feet, thickened nerves, and trophic ulcers.

[16][17] In 2011, podoconiosis was added to the World Health Organization's neglected tropical diseases list, which was an important milestone in raising global awareness of the condition.

[23] Once the disease has developed, rigorous foot hygiene including daily washing with soap and water, application of an emollient, and nightly elevation of the affected extremity has been shown to reduce the frequency of acute attacks.

[12] Ernest W Price, a British surgeon living in Ethiopia, discovered the true etiology of podoconiosis in the 1970s and 1980s by studying the lymph nodes and vessels of those afflicted with the disease.

After examining the same tissue using electron microscopy, he could identify the presence of silicon, aluminum, and other soil metals both in the phagosomes of macrophages and adhered to the surface of lymphocytes.

[30] Price demonstrated that the lymphatic vessels of these patients experienced subendothelial edema and eventual collagenization of the lumen leading to complete blockage.