Podoconiosis (''dust in the feet') presents as bilateral asymmetrical swelling of the feet and lower legs. It is seen in susceptible families of bare-footed farmers in well-defined fertile volcanic highland zones of Africa, Central and South America, and Indonesia, and also in the lowlands irrigated by rivers from these highlands. It is due to the absorption of silica particles from the soil, through the feet of someone from a susceptible family. This causes the patient's lymphatics to fibrose, and obstruct, and his femoral nodes to enlarge. This in turn makes his legs and feet swell, and progress through stages which are described as ''water bag', ''rubbery', and ''wooden'. Finally, his leg becomes hyperkeratotic, ''mossy', and nodular. Lymph may ooze through his skin, which may be secondarily infected by fungi or bacteria. The disease may progress steadily, or there may be a succession of acute episodes which resolve incompletely. Villagers in endemic areas are often able to recognize the early stages.
Elevation, elastic stockings, and long leather boots help in the earlier stages, but once the ''wooden' stage has developed, the only treatment is surgical. If you see a patient early, persuade him to wear boots or shoes which will minimize further progression. The main preventive measure is wearing fully protective shoes from childhood. Sandals, or shoes with many open spaces on their uppers, may not protect.
Podoconiosis is disfiguring, and may make the patient a social outcast, so treatment is important. Unfortunately, by the time you see him, his lymphatics will probably be incurably blocked, so that medical treatment is unlikely to be effective. Surgically, you can: (1) Compress the leg of a ''soft' case in a decompression machine (if you have one), excise the folds of superfluous skin and subcutaneous tissue that are left after decompression, and then bring his skin edges together. (2) Excise the thickened tissue of a ''hard case', and graft the bare area. (3) Excise individual nodules. Or you can combine these procedures. Surgery is said to be simple and beneficial, but opinions differ.
Price EW, ''The pre-elephantiasic stage of non-filarial elephantiasis of the lower legs: podoconiosis'. Tropical Doctor 1984;14:115[nd]119[-3] Price EW, ''Management of endemic (non-filarial) elephantiasis of the lower legs'. Tropical Doctor 1975;5:70[nd]75. Fig. 31-3 DIAGNOSING PODOCONIOSIS. A, ''block toes'. Early oedema of a patient's forefoot affects the plantar aspect of his metatarsal pad, as well as his toes, which appear rigid, as if they were wooden and nailed on to his forefoot. They may be lifted off the floor by plantar oedema, and lack the usual curve of normal toes. B, ''knocking' big toes on walking, due to splaying of the forefeet as the result of deep oedema at the level of the metatarsal heads. C, and D, increased skin markings, which become more evident if his toes are compressed, as in D. Flies, attracted by exuded lymph to an otherwise clean foot, are characteristic. E, a wet ''waterbag' foot, which is readily reduced by compression or elevation; its skin is soft, and you can pinch it off the bone. F, the dry ''wooden' type, which cannot be reduced by compression or elevation; it is hyperkeratotic, and often nodulated. After EW Price.
PODOCONIOSIS EARLY DIAGNOSIS. After a long day's work in the fields, or a long walk, one of a patient's feet becomes swollen, and feels tense. His lymph nodes are enlarged and firm. For the differential diagnosis see the previous section. Try to recognize the following early stages:
''Burning leg' He has a burning sensation in his lower leg, from in front of his medial malleolus to behind the medial condyle of his knee, sometimes extending upwards into his thigh. His femoral nodes may be tender. Pain is usually worst at night, and is relieved by uncovering his leg. Each episode usually affects the same leg, and the second leg does not usually become involved until the first one shows clear signs of disease. Although the burning area of the leg may be tender, few patients seek help at this stage.
''Itchy foot' is a persistent localized itching, usually on the dorsum at the base of the first or second toe clefts, or below the middle malleolus. Thickening of the skin (pachydermia), from constant scratching, may bring him to the clinic. When his toes start swelling, the itchy area precedes the upper level of the swelling, and indicates progression of the disease.
''Splayed forefoot' is a widening of his forefoot, and separation of his toes, which gives his foot a spatula-like appearance, on one or both sides (B, in Fig. 31-3). It is due to deep oedema between his metatarsal heads. His skin is unusually resistant to being lifted by your fingers.
Plantar oedema is asymmetrical (unlike cardiac or renal oedema). Press with your thumb on his sole over the head of his first metatarsal. Test for it when he has recovered from any temporary physiological oedema, which may be the result of walking a long way to the clinic. You may see mild lymphatic oozing, tiny blebs of lymph, or an an unusual number of flies attracted to it.
A pachydermic forefoot shows an excessive deposit of keratin on the dorsum at the base of the first or second toe cleft. The clefts themselves usually remain normal, even in advanced disease.
Increased skin markings at the base of the first toe cleft and running longitudinally rather than laterally (as is normal). Compressing them, as in D, Fig. 31-3, shows them more clearly.
''Block toes' lack their normal curves, and look wooden and rigid, as if they were nailed on the forefoot (A).
Fig. 31-4 TREATING PODOCONIOSIS. A, an intermittent compression machine in use (the foot has been lowered for ease of illustration, and should be raised). B, a ''waterbag' foot before decompression in the machine. C, the same foot, after the machine has reduced the swelling over the lower leg, but not over the dorsum of the foot. D, excess skin and tissue have been removed and the bare area grafted. E, the grafted leg protected in a boot. F, nodulation. G, how to excise a nodule. After EW Price, by kind permission of the Editor of Tropical Doctor.
EARLY TREATMENT. Advise him like this: ''(1) Raise the foot of your bed to the height which relieves the discomfort; a hammock is suitable. (2) Put on ankle-length elastic socks before rising in the morning; or apply wide (10 cm) one-way stretch elastic bandages; crepe bandages are inadequate. (3) Protect the skin of your feet from the soil, preferably in shoes. (4) Choose another occupation which does not involve contact with the soil (difficult). (5) Move to a non-endemic area (even more difficult)''. Meanwhile, treat whatever other conditions he has (parasites, anaemia, etc.).
CAUTION ! Don't try to remove his femoral nodes.
EXCISION OF FOOT NODULES. Excise them for aesthetic reasons, or to make wearing shoes easier. They have no sensory nerves, so you can remove them without anaesthesia, which is useful, because they are so thickly indurated that infiltration may be impossible.
INTERMITTENT COMPRESSION AND THE EXCISION OF REDUNDANT TISSUE. Start by reducing the size of the swellings with the intermittent compression machine in A, Fig. 31-4.
Have blood cross-matched. With a tourniquet applied (essential), make an incision from the upper level of the loose skin behind his medial malleolus, along the medial side of the dorsum of his foot, and then lateraly across the dorsum. Excise the loose skin. If bringing the skin edges together is difficult, graft the raw area (D, 31-4). Advise him to wear stockings and boots (E).
EXCISION ALONE. See also Charles' operation in Section 31.6.
Fig. 31-5 SOME FILARIAL LESIONS A, extensive filarial involvement of the leg. After the operation she could walk without support. B, an East African woman with an axillary swelling; needle puncture showed that this was a lymphatic varix. C, this filarial mass required amputation; after the operation the patient only weighed only half as much as he did before. D, elephantiasis of the scrotum with involvement of the groin glands, but without involvement of the penis. E, a lymphocele of the cord. F, an encysted lymphocele. G, a strangulated hernia with an encysted lymphocele (rare). After R. Mahadevan, and John Spencer, with the kind permission of the editor of ''Tropical Doctor'.