What is a Macular Rash?

Macula refers to a localized or diffuse change in skin color. Generally, it is not raised or sunken. It is one of the most common primary lesions in dermatological symptoms. Generally smaller, less than 1-2cm, those greater than 2cm are called patches. Macular rash can be divided into two types: inflammatory and non-inflammatory. Some rashes also have scaly, called scaly rash, such as the rash of pityriasis versicolor.

Basic Information

English name

macula

Visiting department

dermatology

Common causes

Inflammatory macular rash is caused by infection, physical, and chemical factors. Non-inflammatory macular rash is caused by changes in pigment, abnormal development of skin blood vessels, and bleeding in the skin.

Common symptoms

Localized or diffuse skin color changes, not raised or sunken

Common causes of macular rash

The most common causes of macular rash are:

1. Infections, such as measles, rubella, viral rash, infantile rash, and infectious mononucleosis caused by viruses; scarlet fever, erysipelas, erysipelas, typhoid, leprosy, etc. caused by bacteria; syphilis, lime Disease, etc .; rickettsial typhus, etc. Others are infections such as chlamydia, which cause rashes of macular rash.

2. Macular rash caused by physical factors, such as fire-induced erythema, frostbite, solar dermatitis, chronic actinic dermatitis, and plant-solar dermatitis.

3. Macular rash caused by allergic diseases, the most common are drug rash caused by drug allergy, seasonal contact dermatitis, contact dermatitis, facial recurrent dermatitis, etc., all are caused by allergic rash and patches .

4. Macular rash caused by autoimmune diseases, such as lupus erythematosus facial erythema, periorbital erythema of dermatomyositis, etc.

5. Macular rash caused by animal factors, common rash-like erythema, jellyfish dermatitis, rice field dermatitis and so on.

6. Congenital hereditary diseases, such as congenital ichthyosis erythroderma, nodular skin sclerosis of tuberous sclerosis, and coffee spot of neurofibromatosis.

7. Spotted rash caused by metabolic and nutritional disorders, such as scaly spotted rash on exposed areas caused by folate deficiency, with clear boundaries.

8. Unexplained macular rash, such as simple circular erythema, lame circular erythema, telecentric circular erythema, persistent pigmented abnormal erythema, etc.

9. Tumor: Carcinoid Syndrome: The peptide hormone serotonin is produced by carcinoids, causing paroxysmal erythema on the face, neck and chest. Glucagonoma Syndrome: Migratory necrolysis and erythematous erythema can occur repeatedly.

Differential diagnosis of macular rash

Through careful observation, check the characteristics and distribution of the rash shape, and combine with the medical history summary analysis to make a correct diagnosis. The histopathological changes of macular rash are relatively shallow, and generally only invade the epidermis and superficial papillae of the dermis, so the damage does not bulge, there is no obvious infiltration when touched, and only the color changes. When we observe spot rash, we mainly check from the following aspects: the shape of the damage: whether it is single or polymorphic. Distribution: systemic symmetry or limited asymmetry; extension or flexion; distribution of those special parts; dense or scattered distribution; strip, band, or nerve distribution; The exposed part is still the covered part. Specific skin lesion characteristics: including size, color, shape, smooth or rough surface, scale characteristics, ecchymosis characteristics, whether there is erosion, exudation, and whether there is ulcer. Must pay attention to observe the oral mucosa, tongue, genital mucosa damage. There are special lesions on the mucosa due to many diseases, such as psoriasis pustular psoriasis is often accompanied by grooved tongue. Oral mucosal plaque is often associated with secondary syphilis.

The histopathological features of macula also have their own characteristics. For example, the pathology of allergic purpura is characterized by leukocyte fragmentation vasculitis and tube wall fibrinoid degeneration in the superficial dermis.

Macular rash treatment principles

Avoid scratching, avoid excessive washing, and keep the skin moisturizing and barrier function.

Treat the cause and control the vector and its potential host.