Skin darkening

Introduction Pigmentation, which is mainly caused by an increase in the number of melanocytes, can cause skin darkening. It is a group of skin diseases characterized by diffuse pigmentation in exposed areas such as face, including Riehl melanosis, occupational melanosis, tribological melanosis, and Sivat skin color ( Civatte heterochromia black disease. Black disease is good for facial brown, dark brown, gray-black pigmentation spots. Some people think it is a photosensitive dermatitis or phototoxic dermatitis after the mutation. It has not been clarified that many cases have a history of contact with coal tar or asphalt, so it can be a toxic black disease.

Cause

(1) Genetic factors

Black skin disease is associated with pigmentation of the plaque, sunspot, and perioral blackspot disease.

(2) Diseases

Color-derived juvenile melanoma congenital color nevus nerve skin blackening disease, blue disease, animal skin and so on.

(3) Congenital or unexplained reasons

Albright syndrome Mongolian plaque, Ota disease Ito, malignant freckle-like melanoma.

an examination

Related inspection

Dermatological microscopy, surgical examination, fungal histopathology

First, the clinical features: occur in adults, more common in women. Beginning with erythema or pale brown spots, it gradually enlarges into dark brown or blue-gray diffuse patches, sometimes with mild itching. Symptoms of the rash are distributed symmetrically, especially in the forehead, cheeks, back of the ears, neck and light. It can also be seen in the chest, hands, and chest. Skin lesions develop slowly, for months or years, and then stop developing. In addition to pigmentation spots, limited telangiectasia, follicular keratotic papules and a little fine desquamation can be seen, resulting in a lead gray. The disease does not involve the mucosa.

Second, histopathology: epidermal basal cells liquefaction metamorphosis, perivascular lymph, tissue cells infiltration in the superficial dermis, visible melanocytes and free melanin.

Differential diagnosis

Dark spots on the skin: What are dark spots, dark spots can be divided into congenital and acquired two kinds.

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