Skin and its Inflammatory pathologies.

Skin is the largest external organ of the body.

It consists of 3 layers;
1) Epidermis
2) Hypodermis
3) Dermis

Epidermis can be further classified into 5 sublayers;
i) Stratum corneum (outermost part, dead cells)
ii) Stratum lucidum
iii) Stratum granulosum
iv) Stratum spinosum
v) Stratum germinativum (innermost layer, all the above layers originate from this layer)

Any injury which does not involve stratum germinativum, will lead to complete healing without scarring.

Otherwise, any injury involving stratum germinativum will lead to scarring formation.

The scar will be less visible if the injury is perpendicular to the sophisticated linings of the skin, called Langer's lines.

These layers are made up of keratinocytes.

Apart from the structural part of the skin, the other functional cells are;
i) Melanocytes (produces melanin, which gives colour to the skin)
ii) Langerhans cells (antigen-transporter from skin, act as phagocytes)
iii) Merkel cells (touch-receptor cells)

melanocytes are stimulated by Melanocyte-stimulating hormone (MSH) from the anterior pituitary. in humans, it is less abundant compared to animals. That is why animals can change their colour of the skin abruptly, but not for humans, unless if you lie on a sunny beach for a whole-day long!

moreover, these MSH does not influence the melanocytes like ACTH does. thus in humans, melanocytes are known to be stimulated more by ACTH, not MSH.

Langerhans cells play an important part in immunity of the skin. And it plays a major role in initiating allergic reactions of the skin.

Merkel cells detect touch. if you do not have any, than you cannot feel anything that touches your skin!

Inflammatory pathologies of the Skin.

Acute Inflammatory Dermatoses
i) Urticaria
ii) Eczema
iii) Erythema Multiforme

Chronic Inflammatory Dermatoses
i) Psoriasis
ii)Lichen Planus
iii) Lichen Simplex Chronicus



Urticaria

Urticaria (hives) is a common disorder mediated by localized mast cell degranulation resulting in dermal microvascular hyperpermeability. Gives rise to wheals.

Character:
-Erythematous (kulit merah)
-Edematous (kulit berair)
-Pruritic (gatal2)

Pathogenesis:
-type I hypersensitivity reaction as a result of IgE sensitization (allergic reaction)
-results of mast cell degranulation
-in turn, releases chemical inflammatory mediators

the allergens (benda yg buat alergi) are mainly;
-pollens
-foods
-drugs
-insect venom

clinical features
-common in 20-40 years of age
-usually heals in a day

treatment (tak payah pun takpe, tapi kalau teruk sangat....)
-antihistamines
-steroids


Eczema

Eczema is a clinical term that embraces a number of conditions with different underlying etiologies.

characterised by;
- red (merah)
- papulovesicular (bintik2 berair)
- oozing (keluar nanah)
- crusted lesions (luka berkerak)

Pathogenesis
-allergens bind to Langerhans cell
-Langerhans cell goes to draining lymph nodes
-presents to naive T cells
-on re-exposure, CD4 cells release cytokines
-inflammatory cells gather to the site
-mediate epidermal damage

clinical features
-pruritic (gatal2)
-edematous (berbonjol. dan berair)
-oozing plaques (bernanah)
-vesicles and bullae
persistence of this leads to;
-scaly skin (kulit macam ada layer baru, sebab hyperkeratosis)
-epidermal thickening (acanthosis)

treatment
-avoid the underlying cause of the source of allergens (jauhi benda yg buat alergi)


Erythema Multiforme

Uncommon, hypersensitivity response to certain infections and drugs.

Characterised by;
-multiform lesions (bengkak bervariasi tempat dan bentuk)

Pathogenesis
-cytotoxic T-cells damages the basal layer of skin, from the stimulation of the infection or drugs

clinical features
-associated with infections
-associated with antibiotics (penicillin, sulfonamides, salicytes, hydantoins, antimalarials)
-associated with NSAIDs (aspirin, diclofenac, ibuprofen)

treatment
-insyaAllah hilang lepas infection subsides
-jangan overdose ubat
-doa byk2 la ye :)

ok, nak pergi ke kelas, chronic inflammatory dermatoses saya sambung bila ada kelapangan, insyaAllah!