Cutaneous Eruptions and Parasitic Conditions of the Anus

These are quite numerous, and they almost invariably produce much distress and excite painful pruritus, which is augmented rather than relieved by scratching or friction of any sort. The application of the leaves of Rhus toxicodendron after defecation is capable of exciting considerable inflammation upon and around the anus, accompanied by small pearly vesicles, which, when ruptured by scratching, seem to spread the disease wherever the contained serum flows. Eczema, when found in the anal region, is usually due to parasitic growth. Erythema intertrigo is caused by the friction of moist opposing surfaces, as between the nates of stout persons, who perspire freely, and infants. The abraded derma exudes a sero-purulent fluid which excites troublesome pruritus. When this condition exists about the anus it causes painful defecation and spasm of the sphincters. Erythema chronicum occurring in this locality is frequently a sequel to chronic eczema and chronic lichen: the skin cracks, is moist, thickens, and the epidermis exfoliates. The proximate cause in both of these conditions is congestion of the vascular rete of the derma. In prurigo podicis papules appear which itch intensely, and when scratched bleed, the summit of each papule bearing a small black scab. If not cured, in time a true psoriasis may develop. Herpes of the anus occurs similar to herpes at the other mucous outlets of the body, and is usually symptomatic of slight disorder of digestion. Wetherill has seen a case of herpes zoster, (var. proserpens,) in which the vesicles extended from the side of the scrotum along the perineum to the verge of the anus. This condition was accompanied with neuralgia of the rectum, painful defecation, and spasm of the sphincters. Furunculi sometimes form at the verge of the anus, causing spasm, pain at stool, and occasionally marginal fistulæ. Various syphilodermata also appear in this region. Gross was the first to describe a condition of trichiasis of the anus—a very irritating complication to fissure—due to a perverted recurvation of the hairs usually found in the anal region. Villermé states that hairs have been found growing from the mucous membrane of the rectum. The colonization of pediculus pubis about the anus occasions a certain amount of irritation. Sarcoptes hominis is sometimes found in this region, having been carried there by hands infested with this parasite. The result is very distressing. The peculiar tracks or burrows made by this little animal, and the use of the microscope, make the diagnosis certain. The Acarus autumnalis, or mower's mite, has been found in the skin of this part, and it is capable of causing great distress. These do not furrow the integument longitudinally, but burrow vertically, and may be picked out of the summits of the wheals, where they appear as small red points.