Dermatology Made Simple : Eczema Pathophysiology,Types of Eczema and Endogenous Eczema

Eczema Pathophysiology  and Types of Eczema:

There is a recognized association with genetic predisposition in patients with atopic eczema.

In these patient,an abnormality of T helper lymphocyte exists (especially TH 2 cells) that have important role in the disease.

These abnormal TH2 cels interact with Langerhan”s cells causing increased levels of interleukins/IgE and reduction in interferon (INF Gamma) resulting in release of pro-inflammatory cells.

Pathology:

There is oedema in epidermis that cuases separation of keratinocuyes and vesicle formation.

Epidermis becomes thickened and blood vessels become dilated.

There would be inflammatory cell infiltrate in dermis ( of eosinophils).

Types of Eczema:

As discussed before Eczema canbe broadly divided into two types:

Endogenous and Exogenous Eczema

Endogenous Eczema/ Constitutional Eczema :

Atopic Eczema

This usually presents in infancy or early childhood.

It affects face and flexural regions.

There is a strong family history and it is associated with Asthma.

Venous Eczema:

This appears on the lower limbs of patients with venous insufficiency

These patients have backflow of blood from deep to superficial veins leading to venous hypertension.

Patients have peripheral oedema and ulceration may occur as well.

There would be brown haemosiderin pigmentation of skin.

Compression is used for treatment.

Asteatotic Eczema:

This occurs on lower legs of elderly people who have dry skin.

Discoid Eczema:

This occurs on lower limbs and is characterized by annular lesions .

Vesicles may also develop.

It is more common in men that women.

Pompholyx Eczema:

It affects fingers palms and soles.

There are itchy vesicular lesions that develop on these areas.