The cause is unknown, and the condition tends to come and go. (ICD-10 L30.0)

Venous
Venous eczema (gravitational eczema, stasis dermatitis, varicose eczema) occurs in people with impaired circulation, varicose veins, and edema, and is particularly common in the ankle area of people over 50. There is redness, scaling, darkening of the skin, and itching. The disorder predisposes to leg ulcers. (ICD-10 I83.1)

Herpetiformis
Dermatitis herpetiformis (Duhrings disease) causes an intensely itchy and typically symmetrical rash on arms, thighs, knees, and back. It is directly related to celiac disease, can often be put into remission with an appropriate diet, and tends to get worse at night. (ICD-10 L13.0)

Neurodermatitis
Neurodermatitis (lichen simplex chronicus, localized scratch dermatitis) is an itchy area of thickened, pigmented eczema patch that results from habitual rubbing and scratching. Usually, there is only one spot. Often curable through behaviour modification and anti-inflammatory medication. Prurigo nodularis is a related disorder showing multiple lumps. (ICD-10 L28.0; L28.1)

Autoeczematization
Autoeczematization (id reaction, auto sensitization) is an eczematous reaction to an infection with parasites, fungi, bacteria, or viruses. It is completely curable with the clearance of the original infection that caused it. The appearance varies depending on the cause. It always occurs some distance away from the original infection. (ICD-10 L30.2)

Viral
There are eczemas overlaid by viral infections (eczema herpeticum or vaccinatum), and eczemas resulting from underlying disease (e.g., lymphoma). Eczemas originating from ingestion of medications, foods, and chemicals, have not yet been clearly systematized. Other rare eczematous disorders exist in addition to those listed here.
The small red bumps experienced in this type of dermatitis are usually about 1 cm in size, red in color and may be found symmetrically grouped or distributed on the upper or lower back, buttocks, elbows, knees, neck, shoulders and scalp. The symptoms of seborrhoeic dermatitis, on the other hand, tend to appear gradually, from dry or greasy scaling of the scalp (dandruff) to scaling of facial areas, sometimes with itching, but without hair loss. In newborns, the condition causes a thick and yellowish scalp rash, often accompanied by a diaper rash. In severe cases, symptoms may appear along the hairline, behind the ears, on the eyebrows, on the bridge of the nose, around the nose, on the chest, and on the upper back. Complications
People with eczema should not receive the smallpox vaccination due to risk of developing eczema vaccinatum, a potentially severe and sometimes fatal complication. Other major health risks for people with dermatitis are viral and bacterial infections because atopic dermatitis patients have deficiencies in their proteins and lipids that have barrier functions along with defects in dendritic cells and as a result are unable to keep foreign invaders out leading to recurring infections. If left untreated, these infections may be life-threatening, so skin barrier improvement (such as daily moisturizing to minimize transepidermal water loss) and anti-inflammatory therapy are recommended as preventative measures. Cause
The cause of dermatitis is unknown but is presumed to be a combination of genetic and environmental factors.