Definition. A chronic, inflammatory disease involving the sebaceous glands and the lanugo hair-follicles, characterized by papules, pustules and nodules.
Symptoms. Acne is one of the commonest diseases of the skin, occurring in over 7 per cent. of all cases. It is more noticeable in private practice because that class of patients are more apt to attend to their external appearance.
Acne simplex or simple acne is usually a blemish of youth, appearing from the twelfth to the eighteenth year and lasting from five to ten years if untreated. It is most often seen on the face, especially on the forehead, cheeks and chin, but it is quite common on the upper part of the shoulders and chest and may rarely be found elsewhere. The eruption is bilateral without symmetry and consists of comedones, papules and pustules from pin-head to split-pea in size, varying in number from one or two to hundreds. The papules may appear independently of comedones, but usually the latter will be noted in the center of the papules and later may be seen in the pustule. It is the rule to find all the lesions from the comedo, the bright to dusky red papule, to the yellowish- white pustule with its red areola in the same individual. Besides these the effects of previous lesions, such as stains which disappear gradually and scars which become less distinct in time, may also be found. Except a sore feeling when pressed upon and, occasionally, a slight burning or itching, there is generally little subjective sensation. Essentially a chronic disease acne, if untreated, may last from the advent of puberty to the time of full maturity, which is a somewhat variable period. It may then disappear spontaneously but some cases develop into the deeper-seated acne indurata while in a few cases the two forms coexist in youth.
Acne indurata may occur in the same localities as acne simplex but it is much more common on the back and neck than the former. It is even more chronic in its course, rarely or never disappearing without treatment. The lesions originate as deep-seated, round, avoid or flattish indurations or nodules, often better felt than seen at their onset. They may be few or many, isolated or aggregated, vary in size from a pea to a cherry, and as they enlarge, the covering skin becomes dark red in color. Most are indolent (blind boil), contain little pus and even if incised are apt to reform. Others suppurate quickly but if not opened there is little tendency to spontaneous rupture, and hence resolution is delayed for weeks. Nearby glands may be affected and the coalescence of several suppurating lesions will often lead to the formation of linear tumors or irregularly shaped nodules which need free incision and cause permanent scarring. These scars are a purplish or deep red and the color fades very slowly. Naturally, the lesions are tender and painful to the touch. Keloidal transformations and fibroid degeneration may follow and persist. Comedones may or may not be present, but when found do not bear the direct pathological relation to pustulation that they do in acne simplex.
Seborrheic diseases often complicate either form of acne, and may slightly alter the typical picture presented. A few conditions, many of which are unlike true acne, have been designated by the term acne and because of this confusing prefix or title, it is necessary to say a word of explanation.
Acne cachecticorum usually occurs in poorly nourished, strumous or scorbutic individuals and is probably partly or wholly tubercular in nature (see scrofuloderma). The lesions are chiefly located on the trunk and extremities and are pea to cherry-sized, flat, flaccid, vivid red formations containing a little seropurulent fluid.
Acne artificialis is a papulopustular eruption produced by the internal use of the iodids or bromids, or from external exposure to tar, paraffin or petroleum (see dermatitis medicamentosa).
Acne rosacea and acne erythematosa (see rosacea).
Acne decalvans (see folliculitis decalvans).
Acne keloid (see dermatitis papillaris capillitii).
Etiology and Pathology. This disease is common, its course is varied, and although a parasitic agent may be locally causative, it would appear that predisposing factors are necessary to make possible the proper surface conditions on which this parasite may develop. Hence it does not seem fair to view acne as either a purely local or purely systemic affection but rather as a combination of both. Concerning the local agents such external factors as a lack of cleanliness, dusty or dirty atmosphere and various drug and trade, or other external irritations, should be considered. Admitting the parasitic element, Sabouraud’s microbacillus of seborrhea is readily found in the comedones and causes the seborrhea while the staphylococcus albus butyricus is added for the acne. Unna and Gilchrist have also described a bacillus that they regard as causative. There is no doubt that staphylococci cause the suppurative lesions. In fact it is positive that a few cases are due to local agents or at least their activity is the chief element in causation.