Erythema (from the Greek erythros, meaning red) is redness of the skin or mucous membranes, caused by hyperemia (increased blood flow) in superficial capillaries. It occurs with any skin injury, infection, or inflammation. Examples of erythema not associated with pathology include nervous blushes. Types
Erythema ab igne
Erythema chronicum migrans
Erythema induratum
Erythema infectiosum (or fifth disease)
Erythema marginatum
Erythema migrans
Erythema multiforme (EM)
Erythema nodosum
Erythema toxicum
Erythema elevatum diutinum
Erythema gyratum repens
Keratolytic winter erythema
Palmar erythema

Causes
It can be caused by infection, massage, electrical treatment, acne medication, allergies, exercise, solar radiation (sunburn), photosensitization, acute radiation syndrome, mercury toxicity, blister agents, niacin administration, or waxing and tweezing of the hairs—any of which can cause the capillaries to dilate, resulting in redness. Erythema is a common side effect of radiotherapy treatment due to patient exposure to ionizing radiation. Diagnosis
Erythema disappears on finger pressure (blanching), while purpura or bleeding in the skin and pigmentation do not. There is no temperature elevation, unless it is associated with the dilation of arteries in the deeper layer of the skin. See also
Hyperemia
Flushing (physiology)
List of cutaneous conditions

References


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Congenital
Congenital lung cavities, or lung cavities present at birth, include bronchogenic cysts, congenital pulmonary airway malformation, and pulmonary sequestration. These congenital lesions are the most common cause of lung cavities in infants, children, and young adults. Bronchogenic cysts are due to abnormal budding of the bronchial tree. About 70% are found in the mediastinum, which is the central part of the chest where the heart is. Another 15 to 20% are intrapulmonary (within the lung), usually in the lower lobes. Congenital pulmonary airway malformation, formerly called congenital cystic adenomatoid malformation, is a benign tumor the results in the formation of single or multiple cysts. Pulmonary sequestration refers to abnormal lung tissue that gets its blood supply from the systemic circulation instead of the pulmonary circulation, like the rest of the lung. This lung tissue is also not connected to the trachea. See also
Focal lung pneumatosis, article comparing lung blebs, bullae, cysts, and cavities


== References ==