According to Crocker in two cases reported by Thibierge, the oral mucous membrane was also stained. Carrington and Crocker both record cases of permanent pigmentation following exposure to great cold. Gautier is accredited with recording in 1890 the case of a boy of six in whom pigmented patches from sepia to almost black began to form at the age of two, and were distributed all over the body. Precocious maturity of the genital organs preceded and accompanied the pigmentation, but the hair was illy developed.
Chloasma uterinum presents some interesting anomalies. Swayne records a singular variety in a woman in whom, during the last three months of three successive pregnancies, the face, arms, hands, and legs were spotted like a leopard, and remained so until after her confinement. Crocker speaks of a lady of thirty whose skin during each pregnancy became at first bronze, as if it had been exposed to a tropical sun, and then in spots almost black. Kaposi knew a woman with a pigmented mole two inches square on the side of the neck, which became quite black at each pregnancy, and which was the first recognizable sign of her condition. It is quite possible that the black disease of the Garo Hills in Assam is due to extreme and acute development of a pernicious form of malaria. In chronic malaria the skin may be yellowish, from a chestnut-brown to a black color, after long exposure to the influence of the fever. Various fungi, such as tinea versicolor and the Mexican "Caraati," may produce discoloration on the skin.
Acanthosis Nigricans may be defined as a general pigmentation with papillary mole-like growths. In the "International Atlas of Rare Skin Diseases" there are two cases pictured, one by Politzer in a woman of sixty-two, and the other by Janovsky in a man of forty-two. The regions affected were mostly of a dirty-brown color, but in patches of a bluish-gray. The disease began suddenly in the woman, but gradually in the man. Crocker has reported a case somewhat similar to these two, under the head of general bronzing without constitutional symptoms, in a Swedish sailor of twenty-two, with rapid onset of pigmentation.
Xeroderma pigmentosum, first described by Kaposi in 1870, is a very rare disease, but owing to its striking peculiarities is easily recognized. Crocker saw the first three cases in England, and describes one as a type. The patient was a girl of twelve, whose general health and nutrition were good. The disease began when she was between twelve and eighteen months old, without any premonitory symptom. The disease occupied the parts habitually uncovered in childhood. The whole of these areas was more or less densely speckled with pigmented, freckle-like spots, varying in tint from a light, raw umber to a deep sepia, and in size from a pin's head to a bean, and of a roundish and irregular shape.
Interspersed among the pigment-spots, but not so numerous, were white atrophic spots, which in some parts coalesced, forming white, shining, cicatrix-like areas. The skin upon this was finely wrinkled, and either smooth or shiny, or covered with thin, white scales. On these white areas bright red spots were conspicuous, due to telangiectasis, and there were also some stellate vascular spots and strife interspersed among the pigment. Small warts were seen springing up from some of the pigment spots. These warts ulcerated and gave rise to numerous superficial ulcerations, covered with yellow crusts, irregularly scattered over the face, mostly on the right side. The pus coming from these ulcers was apparently innocuous. The patient complained neither of itching nor of pain. Archambault has collected 60 cases, and gives a good resume to date. Amiscis reports two cases of brothers, in one of whom the disease began at eight months, and in the other at a year, and concludes that it is not a lesion due to external stimuli or known parasitic elements, but must be regarded as a specific, congenital dystrophy of the skin, of unknown pathogenesis. However, observations have shown that it may occur at forty-three years (Riehl), and sixty-four years (Kaposi). Crocker believes that the disease is an atrophic degeneration of the skin, dependent on a primary neurosis, to which there is a congenital predisposition.
Nigrities is a name given by the older writers to certain black blotches occurring on the skin of a white person--in other words, it is a synonym of melasma. According to Rayer it is not uncommon to see the scrotum and the skin of the penis of adults almost black, so as to form a marked contrast with the pubes and the upper part of the thighs. Haller met with a woman in whom the skin of the pubic region was as black as that of a negress.
