Blue, bluish-gray, or bluish-black papules

Introduction Common blue nevus (common blue nevus) Women are more common, usually acquired, from childhood, occur in the face and extremities, especially the back of the hand and waist and hip. Skin lesions are mostly single, even or several, often no more than 1cm in diameter, grayish blue or blue-black nodules, top round, solid texture, can be fused into a piece, the boundary is clear. Expressed as blue, blue-gray or blue-black pimples. It can occur anywhere, but half of it occurs on the back of the hand and the back of the foot. This type of blue dragonfly is generally not malignant. It is a clinical manifestation of blue dragonfly.

Cause

(1) Causes of the disease

Blue sputum is caused by the accumulation of abnormal melanocytes in the dermis, which is rare, and is often associated with pigmented nevus, cardiac myxoma, mucocutaneous mucosa (LAMB syndrome), and associated with nodular mast cell proliferation. Its histology has a certain relationship with pigment cells and mast cells.

Through ultrastructural and acetylcholinesterase activity analysis, it is speculated that blue mites may originate from Schwann cells or endogenous nerves. However, blue sputum cells can synthesize melanin and suggest a melanocyte source. It is considered that normal melanocytes appear in abnormal parts and have abnormal functions. Therefore, it is speculated that both common blue mites and cell sputum are benign proliferation from abnormal pigment cells of neural crest.

The blue-gray appearance of the blue dragonfly is mainly the visual effect produced by the dermal melanin covering the epidermis. The long wave of visible light is absorbed by the pigment cells through the deep dermis, while the short wave (blue) cannot be absorbed, and then reflected to the viewer's eye in blue. The occurrence of explosive blue sputum is related to sun exposure, and pigmented tumors with histological features of blue sputum can be induced by DMBA in hairless mice or guinea pigs.

(two) pathogenesis

The pathogenesis is still unclear. There are three kinds of histopathological forms of blue dragonfly:

1. Common blue nevus The number of dermal melanocytes is large, mainly in the dermis, deep, even or down to the subcutaneous tissue or up close to the dermal papilla. Melanocytes are long spindle-shaped, fibroblast-like, containing melanin, positive for Dopa. The dermal mesh layer has a wide range of fibrous tissue production. In the melanocyte aggregation, unequal amounts of fibroblasts and melanocytes are often mixed. The latter is different from melanocytes in that the cell body is larger, the melanin particles are thicker, and the dendritic Dopa reaction is negative.

2. Cellular blue nevus can be seen in common blue scorpion components, such as pigmented dendritic cells. In addition, some spindle cells are common, their cell bodies are large, the nucleus is oval, the cytoplasm is rich, the staining is light, and the melanin is rare or absent. These cells are often closely arranged in an island or cord, and melanocytes rich in melanin are seen around them.

3. Combined blue nevus Blue scorpion itself can be either normal or cell type. Concurrent sputum cell sputum, which can be junction , intradermal or mixed , rarely Spitz.

an examination

Related inspection

Physical examination of skin fungus microscopic examination of skin diseases

According to clinical features, the diagnosis of blue sputum is not difficult, but the diagnosis requires pathological examination.

Differential diagnosis

Differential diagnosis of blue, blue-gray or blue-black papules:

1. Blue rubber blisters: Blue rubber bleb nerus syndrome: This syndrome is rare, characterized by simultaneous spongiform or capillary hemangioma in the skin and digestive tract. It is blue-spotted. If a rupture occurs, it can cause bleeding.

2, facial hemispherical blue-black nodules: capillary or venous thrombosis clinical manifestations: hemispherical or mildly lobulated nodules, medium hardness, ranging from 2 to 10 mm, the color is blue-black.

3, heel blue black or black spots: heel ecchymosis damage is clustered blue black or black spots.

4, blue sputum malignant transformation in addition to melanocytes atypical, common necrotic foci, and see residual melanocytes.

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