Trigger 1

A 30 years old woman, presented to the General Medical clinic, complaining of an itchy rash on her head. Having noticed the rash about 2 months ago, it had worsened recently where she had scaly lesions in her elbows, knees and in the buttocks.
Her husband died from a road traffic accident a month ago.

Trigger 2

She went on to report that following abrasions to her elbow when she accidentally slipped and fell down a few days ago, more lesions had appeared there. Systemic review was unremarkable, and she was not on any medication. Her mother was being treated for Arthritis.

Trigger 3

On examination she looked well and was afebrile. Her pulse was 76/min and BP 110/60 mmHg. There were eythematous, sharply demarcated plaques coverd by silvery scales on her scalp, elbow, knees and gluteal cleft. Ther was also some punctuate pitting of her fingernails. The rest of the examination revealed no other significant abnormalities. A provisional diagnosis of psoriasis was made.
A skin biopsy was performed and histopathological features were observed.
She was offered advice on skin care, and commenced treatment with topical Glucocorticoids. She did not improve favorably and thus oral gucocorticoids and topical psoralens with ultraviolet light-A (PUVA) were added.

Trigger 4

15 years later, when she attended the Rheumatology clinic, she was much worse. Her skin lesions were widespread and now had an asymmetrical arthritis involving her proximal and distal interphalangeal joints, ankles, knees , hips and temperomandibular joints. He finger nails were separated from the nail bed. She was also found to have iritis. She was not cushingoid and was nomotensive.

Trigger 5

Investigations included:
ESR 60 mm/hr
CRP positive 2+
RhF negative
Autoantibodies negative
Uric Acid: 6 mg/100ml ( normal 2.0 _ 6.0 mg/100ml )
Fasting serum glucose 90mg/100 ml
X-ray of the hands: showed proliferative erosions plus increased sclerosis of small bones ( ivory phalanx )
Bone Densitometry: No evidence of osteoporosis seen
A diagnosis of a seronegative psoratic arthritis was made.

Trigger 6

Following an Ophthalmology consult for her iritis review of her investigations, she was commenced on a NSAID in addition to Methotrexate 5mg/week and Folic Acid 1mg/day with careful monitoring of her CBC, renal profile and liver biochemistry.

Objectives :
1. causes of scaly lesions
2. Histology of skin & function of skin
3. Psycological trauma skin disease
4. History taking in skin disease
5.psorasis ( def, epidemo, type,.........etc)
6. skin biopsy (types, indications,teq,finding ..)
7.ttt of psorasis
8. psorasis Arthritis (clinical features , investigation , treatment)
9. complication+follow up+ prognosis
10. ttt of iritis
11. nail abnormalitiy


1- Non- infectious, chronic inflammatory disease of the skin, with defined erythematous plaques with silvery scales.
2- Starts at any age. / but unusual before age 5.
3- Two pathophysiological aspects:
* Keratinocytes hyperproliferate...involving retention of nuclei in St. Corneum.
* Large inflammatory cell infiltrate.
4- Patholoy :
- Parakeratosis
- Dilated & tortuous capillary loops
-Irregular thickening of epidermis
- & upper dermal T-lymphocyte infiltrate.
5- Types...( plaque psoriasis, Guttate psoriasis, Erythrodermic psoriasis, Pustular psoriasis)

The following medical conditions are some of the possible causes of Scaly skin:-

Fungal skin infection
Bowen's disease
Exfoliative dermatitis
Nummular eczematous dermatitis
Seborrheic dermatitis
Hodgkin's disease
Malignant lymphoma
Chronic parapsoriasis
Pityriasis rosea
Pityriasis rubra pilaris
Systemic lupus erythematosus
Tinea versicolor


Psoralen and ultraviolet A phototherapy (PUVA) combines the oral or topical administration of psoralen with exposure to ultraviolet A (UVA) light.

Mechanism of action:

probably involves activation of psoralen by UVA light which inhibits the abnormally rapid production of the cells in psoriatic skin.


nausea, headache, fatigue, burning, and itching.
Long-term treatment is associated with squamous-cell and melanoma skin cancers.

Types of Psoriasis:

Plaque psoriasis (psoriasis vulgaris):

- Is the most common form of psoriasis.
- It affects 80 to 90% of people with psoriasis.
- Plaque psoriasis typically appears as raised areas of inflamed skin covered with silvery white scaly skin.
- These areas are called plaques.

Flexural, Inverse psoriasis:

- Appears as smooth inflamed patches of skin.
- It occurs in skin folds, particularly around the genitals (between the thigh and groin), the armpits, under an overweight stomach (pannus), and under the breasts (inframammary fold).
- It is aggravated by friction and sweat, and is vulnerable to fungal infections.

Guttate psoriasis (Raindrop Psoriasis):

- Is characterized by numerous small oval (teardrop-shaped) spots.
- These numerous spots of psoriasis appear over large areas of the body, such as the trunk, limbs, and scalp.
- Guttate psoriasis is associated with streptococcal throat infection.

Pustular psoriasis:

- Appears as raised bumps that are filled with non-infectious pus (pustules).
- The skin under and surrounding pustules is red and tender.
- Pustular psoriasis can be localised, commonly to the hands and feet (palmoplantar pustulosis), or generalised with widespread patches occurring randomly on any part of the body.

Erythrodermic psoriasis:

- Involves the widespread inflammation and exfoliation of the skin over most of the body surface.
- It may be accompanied by severe itching, swelling and pain.
- It is often the result of an exacerbation of unstable plaque psoriasis, particularly following the abrupt withdrawal of systemic treatment.
- This form of psoriasis can be fatal, as the extreme inflammation and exfoliation disrupt the body's ability to regulate temperature and for the skin to perform barrier functions.

Nail psoriasis :

- Pitting is the most common finding.

- Loosening (Onycholysis) with subangual hyperkeratosis.

- Oil spot (specific).

- Discolouring under the nail plate.

- Lines going across the nails.

- Thickening of the skin under the nail.

- Crumbling of the nail.

Skin biopsy


Surgical sampling of the skin.

Advantage: can distinguish other elements of the differential diagnosis
Disadvantages: those of minor surgery

Inflammation, vascular ectasia, acanthosis.

Cause of abnormal result:

Inflammatory component and epidermal hyperproliferative response.

Medications, disorders and other factors that may alter results


A shave biopsy takes a thin slice off the top of the skin and can be used to remove superficial abnormal areas (lesions).

A punch biopsy takes a core (a small cylindrical fragment of tissue from the area of interest) and can be used to remove small lesions as well as diagnose rashes and other conditions.

Excisional biopsies are usually larger and deeper and are used to completely remove an abnormal area of skin such as a skin cancer.