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(Podoconiosis from the Greek podos, a foot and konia, dust.)


Endemic elephantiasis. Nonfilarial elephantiasis. Bigfoot disease. Idiopathic elephantiasis. Microcrystal disease. Mossy foot. Lymphostatic verrucosis.


Nonfilarial, noninfective, usually crystalline blockage of the limb lymphatics, almost always affecting the lower limbs and especially the feet.

Geographic Distribution

Podoconiosis is most prevalent in Africa and especially in the higher altitude regions in the eastern and central part of the continent (Ethiopia, Rwanda, Burundi, Cameroon, and Tanzania). The disease also occurs in West Africa (equatorial Guinea), Canary and Cape Verde Islands, Central America, northern South America, Colombia, Ecuador, Brazil, northwest India, and Sri Lanka. Cases have been seen in visitors who have returned to Europe.

Etiology and Pathology

Podoconiosis is a disease of agrarian people who work barefoot, particularly on red clay soil in the neighborhood of volcanoes, either inactive or active, especially at altitudes over 1000 m. Tiny microparticles of silica from the volcanic soil and aluminosilicates penetrate the skin of all who work in this manner. These soils are cytotoxic to macrophages, causing lymphatic obstruction. Depending on the size of the particles (usually 2-25 um), the local lymphatics in the foot may be obstructed or there may be more proximal regional lymph node entrapment, fibrosis, and subsequent obstruction at the lymph nodes. The end result, sometimes referred to as "big foot disease;" is chronic lymphatic obstruction and fibrosis (Fig. 26.40). Fibrosis and hyperkeratosis of the skin is common, as is superinfection with M. tuberculosis, other fungi, or bacteria. (It must be noted that not all histopathologists accept this "soil" theory, while others seem convinced of this explanation.)

Clinical Characteristics

Podoconiosis first becomes symptomatic in the early teens. Both sexes are equally affected. Nocturnal leg and foot pain in a young person is a classic feature. Symptoms flare with exertion, usually starting with itching, burning, and swelling in the sole of the foot, and then spreading proximally up the leg to the level of the knees. The thighs are rarely involved and leg swelling tends to be asymmetrical although both legs are involved. Femoral and inguinal lymphadenitis is common. As in filarial elephantiasis, there is a spectrum of leg findings, from simple lymphedema to a large, leathery, pigmented foot and lower leg (Fig. 26.41).

Imaging Diagnosis and Treatment

When there is gross elephantiasis, there will be underlying bone changes and the marked soft tissue thickening can be demonstrated. In some patients it may be necessary to exclude both bone and deep soft tissue infection, and ultrasonography will be helpful. But apart from these complications, imaging has little to contribute for the majority of patients. Lymphangiograms have shown small filling defects and blockage of regional lymph nodes, bypassed by collaterals.

Surgical removal of a thick layer from the foot and lower leg, resembling a thick sock, has been used to make walking easier. Radiographs of the leg to exclude underlying bone infection are a wise precaution before such a procedure.

Podoconiosis could be completely prevented if those at risk were to wear shoes.



Fig. 26.41 A-D. Idiopathic elephantiasis (podoconiosis). A A young Ethiopian with bilateral idiopathic elephantiasis and marked lymphostatic verrucosis on both feet. The most severe changes affect the ankles and feet. B-D Three views of the left lower leg and foot of an African from Zimbabwe. There is thick diffuse hyperkeratotic swelling, again confined to the lowest part of the leg, ankle, and foot. The calf and above the knee were almost normal. The other foot was normal and radiographs of the left foot were normal except for the soft tissue changes. (A courtesy of Dr. E. W. Price, from Itakura 1995.

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