From the fact that it is possible to inoculate a person by rubbing verruga material on a scarified surface it would seem that the infection might be transmitted by insects.
As regards the pathology of verruga, Cole has noted involvement of the lymphatic channels, which become obstructed by a cellular exudate, around which lymphatics are found plasma cells and fibroblasts. There is marked dilatation of the capillary blood vessels. The structure of these granulomatous tumors is very vascular, almost cavernous, hence the tendency to haemorrhage. The haemolysin may also be operative in the liability to haemorrhage.
Strong and his colleagues found the early lesions to consist of newly formed blood vessels lying in an oedematous connective tissue. The endothelial cells lining them may be in more than one layer. Around these blood vessels we have aggregations of cells which are considered as angioblasts. These angioblasts show frequent mitotic figures. There is a resemblance to a fibrosarcoma.
Symptomatology and Treatment
The period of incubation is about two weeks as shown by experimental inoculation but may be as long from the standpoint of clinical observation as forty days. At the onset we have rather severe pains of joints, especially the knees, ankles and wrists, together with a fever sometimes reaching 104°F. but usually not above 100°F. Following the eruption, the temperature usually subsides to normal in a few days. The eruption shows two types, the one with numerous, small, wart-like lesions, not exceeding the size of a small pea (2 to 5 mm.)—the miliary type, and the other, with less numerous but much larger nodular masses—the nodular type. The latter type is more rarely seen than the former.
Fig. 136.—Verruga Peruviana. (From Ruge and zur Verth.)
The Miliary Type.—The eruption is most abundant on the face and extensor surfaces of the extremities and less common on the trunk. In this type a pink macule appears which rapidly takes on a bright red color and becomes nodular. These nodules may be flat or somewhat pedunculated and bleed easily. At first smooth and shiny, it later on shrivels up without leaving a scar. This form of the eruption may involve the mucous membranes, as of conjunctivae, nose, pharynx, etc. In children the disease is usually of a mild type.
The Nodular Type.—The nodular eruption develops slowly and the lesions may become as large as a pigeon’s egg. They tend to become strangulated and then show as ulcerating, fungating masses which are a source of danger from haemorrhage. The nodular eruption does not invade mucous membranes and is usually confined to the regions of joints, as flexures of elbows, knees, etc.