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.
There are also several cancers that have been shown to be linked with mutations in the AKT pathway, including melanoma and lung cancer. Pur-alpha
Pur-alpha (purα) is a sequence-specific single-stranded DNA and RNA-binding protein. Studies have shown that the protein is primarily active during early development and is believed to have a role in brain enlargement. Although the exact function is still controversial, it is believed that pur-alpha is responsible for neuronal proliferation during neurogenesis as well as the maturation of dendrites. Thus, pur-alpha is also considered a potential root cause of megalencephaly and brain overgrowth. Pathophysiology
One impact of megalencephaly is the complete lack of motor development. One medical study assessed three patients presenting megalencephaly who showed severely impaired motor and speech development as well as distinct facial abnormalities including skull bossing, a low nasal bridge and large eyes. Diagnoses
Diagnosis of megalencephaly has changed over the years, however, with the development of more advanced equipment, physicians have been able to confirm the disorder with better accuracy. Usually, a physical exam is first performed when characteristics of megalencephaly have appeared. This typically occurs at birth or during early child development. A physician will then take head measurements in order to determine the circumference. This is known as the head circumference. Then a family background will be recorded in order to determine if there has been a history of megalencephaly in the family.A neurological exam will then be performed using the technology of an MRI machine in order to confirm the diagnosis of megalencephaly.