contagiosum is a disease more common in childhood than in after-life. It is often seen in London children, especially amongst the poor, but appears to be less prevalent in country districts, or even in other large towns in England. The contagious nature of the disease is now well established. It may be communicated by one child to another, or by a sucking infant to its mother's breast, and Dr. R. Liveing states that he has seen nine children of the same school all affected with molluscum at the same time. In addition to being contagious the disease may also arise spontaneously.
_Morbid exact seat of molluscum contagiosum is still a matter of debate. Many observers hold the view that the little tumours have their seat in the sebaceous glands of the skin. This was long ago denied by Virchow, and after this authority others have supported the opinion that the bodies consist of a morbid growth of the cells of the cutis. Sections of the tumours show that some are simple cyst-like bodies, others are lobulated and surrounded by a fibrous capsule from which fine septa pass between the lobules. The subject has been lately investigated anew by Dr. Sangster, who concludes, as a result of his observations, that mol luscum contagiosum is a disease of the epidermis in which three layers take part. The external portion is formed by the cells of the rete, for on care ful vertical section of the earliest specimens procurable the rete is seen in direct continuity with the lobular expansions of the new growth. The cells probably undergo simple hyperplasia, and those placed at the border are elongated and vertical. Next to these is a granular layer composed of polygonal cells more or less infiltrated with fat-globules. In the centre are roundish bodies, translucent and watery-looking, which are called "molluscum corpuscles." All these are arranged in masses which lie in the meshes of a granular reticrdum. The tumour is covered by the more
superficial layer of the corium, and at its base is a network of fine ves sels.
contagiosum appears in the form of small, white, hard, translucent swellings which gradually increase in size until they reach the dimensions of a pea, or even a nut. Their form is circular, with a flattened top, and at this part is seen a minute depression, which is supposed by those who recognise the sebaceous origin of the tumours to be the mouth of the sebaceous cyst. The smaller growths are usually sessile ; the larger are pedimculated. A. milky-looking thickish juice can be squeezed out of the central depression, especially if a puncture has been previously made with the point of a lancet.
There is no itching or uneasiness connected with the growths in their ordinary state, but sometimes one will inflame and be converted into a pustule. When left alone the tumours gradually dry up, leaving some thickening at their site. The older ones are usually succeeded by a fresh crop.
Their seat is usually the skin of the face, the eyelids, or the neck, but they may be also seen on the chest, abdomen, genitals, and inner part of the thighs.
Diagnosis.—These tumours must not be confounded with the mollus cum fibrosum, which is altogether a different disease. These are small bodies of solid, somewhat gelatinous structure, and consist, according to Rokitansky, of a protrusion of the corium, "which is pushed forwards by accumulation of young, gelatinous connective tissue in one of its deepest meshes." They have no umbilication like the contagious molluscum, and no milky juice can be obtained from them by pressure.
Treatment.—The smaller tumours must be touched with nitric acid or other strong caustic. The larger must be divided with a lancet and the contents squeezed out. A little caustic can be afterwards applied.