, may be found in the subcutaneous tissue in the shape of small nodules, covered by unaffected skin. When young these tumors are tense and elastic, but are subject to calcareous changes. They occur frequently on the back.
Echinococcus Cysts
are also found in the skin, where they may attain a size which will make them fluctuate. The treatment for all such lesions is complete eradication.
Trophoneuroses.
Perforating Ulcer of the Foot.
—This has already been alluded to in the chapter on Ulcers and Ulceration. The lesion apparently begins as a thickening or callosity, usually beneath the head of the first metatarsal bone, at a point where much pressure is made, owing to the natural position of the foot. Beneath the thickened skin there develops an adventitious bursa, in which, or in the skin itself, the first degeneration may take place. The result is a deep ulcer, with overhanging borders, and a thin, often foul discharge. The lesion is not painful, and patients are less likely to spare the foot. It is usually associated with some central spinal disease, or with a peripheral neuritis. It is more common in those patients who have had disease leading to loss of sensation in the foot.
The treatment consists in excision of the ulcer down to healthy tissues, with careful protection. Skin grafting is often found successful.
Ainhum.
—Ainhum is essentially a disease of the negro and of tropical climates. It usually begins in the little toe or little finger, and goes on to spontaneous amputation, the result of an anemia caused by the formation of a sclerotic ring, which encircles the digit and shuts off the blood supply. It is an annular scleroderma, or keloid, which produces the disturbance.