TAILIEUCHUNG - Chapter 054. Skin Manifestations of Internal Disease (Part 12)

In the diffuse forms of hyperpigmentation, the darkening of the skin may be of equal intensity over the entire body or may be accentuated in sun-exposed areas. The causes of diffuse hyperpigmentation can be divided into four major groups—endocrine, metabolic, autoimmune, and drugs. The endocrinopathies that frequently have associated hyperpigmentation include Addison's disease, Nelson syndrome, and ectopic ACTH syndrome. In these diseases, the increased pigmentation is diffuse but is accentuated in the palmar creases, sites of friction, scars, and the oral mucosa. An overproduction of the pituitary hormones α-MSH (melanocyte-stimulating hormone) and ACTH can lead to an increase in. | Chapter 054. Skin Manifestations of Internal Disease Part 12 In the diffuse forms of hyperpigmentation the darkening of the skin may be of equal intensity over the entire body or may be accentuated in sun-exposed areas. The causes of diffuse hyperpigmentation can be divided into four major groups endocrine metabolic autoimmune and drugs. The endocrinopathies that frequently have associated hyperpigmentation include Addison s disease Nelson syndrome and ectopic ACTH syndrome. In these diseases the increased pigmentation is diffuse but is accentuated in the palmar creases sites of friction scars and the oral mucosa. An overproduction of the pituitary hormones a-MSH melanocyte-stimulating hormone and ACTH can lead to an increase in melanocyte activity. These peptides are products of the proopiomelanocortin gene and exhibit homology . a-MSH and ACTH share 13 amino acids. A minority of the patients with Cushing s disease or hyperthyroidism have generalized hyperpigmentation. The metabolic causes of hyperpigmentation include porphyria cutanea tarda PCT hemochromatosis vitamin B deficiency folic acid deficiency pellagra malabsorption and Whipple s disease. In patients with PCT see Vesicles Bullae below the skin darkening is seen in sun-exposed areas and is a reflection of the photoreactive properties of porphyrins. The increased level of iron in the skin of patients with hemochromatosis stimulates melanin pigment production and leads to the classic bronze color. Patients with pellagra have a brown discoloration of the skin especially in sun-exposed areas as a result of nicotinic acid niacin deficiency. In the areas of increased pigmentation there is a thin varnish-like scale. These changes are also seen in patients who are vitamin B6 deficient have functioning carcinoid tumors increased consumption of niacin or take isoniazid. Approximately 50 of the patients with Whipple s disease have an associated generalized hyperpigmentation in association with diarrhea weight .

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