Guttate psoriasis

- distinctive acute eruption of small, drop-like, 1-10mm in diameter, salmon-pink papules, usually with a fine scale
- URTI from group A beta-hemolytic streptococci often precedes the eruption by 2-3 weeks
- primarily occurs on trunk and proximal extremities

Cheiroarthropathy

- condition of limited joint mobility that occur in diabetics
- characterised by thickening of skin resulting in contracture of fingers
- unable to extend the fingers to fully flatten the hand
- treatment: pain relieve, phystiotherapy, tight glycemic control

Erythema gyratum repens

- characteristic concentric erythematous bands forming a wood-grain appearance
- associated with malignancy in up to 80% of patients
- most develop the eruption before the symptoms of malignancy

Calciphylaxis

- calcific uremic arteriolopathy seen almost exclusively in patients with advanced CKD
- heralded by livedo reticularis and advances to patches of ischemic necrosis especially on the legs, thighs, abdomen and breasts
- pathologically, there is vascular occlusion associated with extensive vascular (calcification of tunica media) and soft tissue calcification
- warfarin is a risk factor of calciphylaxis ( because warfarin decrease vitamin K dependent regeneration of matrix GLA protein which is important in preventing vascular calcification)
- optimal treatment is prevention, with rigorous and continuous control of phosphate and calcium balance
- no specific treatment

Scabies

- caused by Sarcoptes scabei, an arachnid
- transmitted by prolonged skin to skin contac with someone who has it
- fertilised female has to be transferred for infestation to take place, she will then find a place to lay eggs (burrow), 4-6 weeks later hypersensitivity rash occurs
- papular rash (on abdomen and medial thigh)
- itchy at night
- diagnosis is confirmed by one or more burrows (in digital web spaces and flexor wrist skin)
- treatment: 5% permethrin cream over whole body including scalp, face, neck and ears. Wash after 8-12 hours
- bedding, clothing and close contacts should be decontaminated (washing in hot water and drying in hot dryer)

Gestational pemphigoid

- a.k.a herpes gestationalis (not associated with herpes virus)
- thought to be caused by autoantibodies which cross react to the basement membrane
- rash can appear anytime after 12th week of pregnancy or just after delivery
- typically starts at the navel area and then spread over the entire body
- diagnosis confirmed by skin biopsy using direct immunofluorescence
- treatment: corticosteroid ointment or oral steroid

Ecthyma gangrenosum

- caused by Pseudomonas aeruginosa
- indurated plaque evolving into hemorrhagic bulla or pustule that sloughs, resulting in eschar formation; erythematous halo; most common in axillary, groin, perianal regions
- usually affects neutropenic patients

Eczema herpeticum

- a.k.a Kaposi varicelliform eruption
- primary infection of eczematous skin with herpes simplex virus
- may be caused by coxsackievirus A16 or vaccinia virus
- usually an abrupt onset with crops (umbilicated vesicles) appearing over 7-9 days and may become coalesced
- high fever for 7 days
- treatment: acyclovir

Yellow nail syndrome

- disorder of lymphatic drainage
- thickened slow growing yellow nails
- associated with pleural effusion and lymphoedema of legs
- 40% also have bronchiectasis

Pityriasis rosea

- self limiting rash commonly seen in adolescent or young adults
- thought to be viral or post-viral rash. Not caused by fungus
- begins as large single pink patch on trunk (Herald patch) followed by generalised body rash lasting for 6 weeks.
- No treatment is required. 1% menthol in aqueous cream may relieve any itch

Cutaneous larva migrans

- caused by larvae of hookworm Ancylostoma braziliense which penetrate skin
- serpiginous, itchy rash
- treatment: 15% solution of topical tiabendazole

Morphoea

- localised scleroderma characterised by firm, white, violaceous patch of skin which usually occurs on thigh, trunk or arms
- begins as erythematous or flesh-colored plaques that become sclerotic, develop central hypopigmentation and demonstrate an erythematous border
- localised morphea (one or a few lesions); generalised morphea (widespread cutaneous lesion without systemic involvement)
- physical therapy to prevent joint contracture and to maintain function
- usually resistant to therapy

Pyoderma gangrenosum

- erythematous nodules or pustules which frequently ulcerate
- typical bluish black undermined edge and a purulent surface
- biopsy: intense neutrophilic infiltrate
- causes: inflammatory bowel disease (UC > Crohn's) , RA, myeloma, leukemia, lymphoma, PBC
- treatment: potent topical steroid, tacrolimus ointment

Lichen planus

- pruritic inflammatory dermatosis commonly associated with mucosal involvement
- associated with autoimmune diseases
- rash is characterised by small, purple flat-topped, polygonal papules that are intensely pruritic
- common on flexor of wrist and lower legs
- genitalia can be affected
- fine lacy white pattern on surface of lesion (Wickham's striae)
- exhibit Koebner phenomenon
- treatment: topical steroid or topical tacrolimus ointment for painful mucosa disease

Erythroderma

- inflammatory skin disease with erythema and scaling that affects nearly entire cutaneous surface
- a.k.a exfoliative dermatitis
- most commonly due to eczema, followed by psoriasis, lymphoma/leukemia, drug (sulphonamide, gold, penicillin, allopurinol)
- complications: hypothermia, fluid loss, capillary leak syndrome, high output cardiac failure
- treatment: emollients and fluid replacement, oral methotraxate for erythrodermic psoriasis

Malignant melanoma

Clinical criteria for diagnosis (ABCDE)

A: Asymmetry of mole
B: Border irregularity
C: Colour variegation
D: Diameter more than 6mm
E: Evolving lesion with changes over time



Clarke's level (reflects level of invasion through dermis)
I : not invaded pass basement membrane
II: involvement of superficial dermis
III: involvement of deep dermis
IV: involvement of subcutis

Breslow's thickness

Tumor Depth	Approximate 5 year survival
<1 mm	95-100%
1 - 2 mm	80-96%
2.1 - 4 mm	60-75%
>4 mm	50%

Pemphigus vulgaris

- chronic blistering skin disease
- painful but rarely pruritic
- mucosal involvement with ulceration
- flaccid blister, especially on trunk
- positive Nikolsky sign
- skin biopsy: superficial intraepidermal split (between keratinocyte and basement membrane)
    - whereas in bullous pemphigoid : subepidermal (between epidermis and dermis)
- antibodies to desmosomal protein 3 (desmoglein 3)
- treatment: high dose steroid

Basal cell carcinoma

- commonest skin cancer
- seen most commonly on face of elderly patient
- predisposing factors: prolonged sun exposure, radiation, chronic scarring, Gorlin syndrome
- nodular BCC is commonest
- characteristic pearly-white raised border
- treatment: excision surgery

Palmar crease xanthoma

- pathognomonic of type III hyperlipidemia (Broad beta disease / remnant hyperlipidemia / familial dysbetalipoproteinemia) - autosomal recessive
- caused by deficiency of apoliproprotein E (ligand for chylomicron)
- characterised by increased LDL, triglyceride and cholesterol, decreased HDL
- have elevation of IDL, a VLDL remnant
- diagnosed by lipoprotein electrophoresis or genotyping of apoprotein E
- also presents with tuboeruptive xanthoma

Xeroderma pigmentosum

- autosomal recessive
- defect in nucleotide excision repair, leading to deficient repair of DNA damage by UV radiation and chromosome breakage (uv light cause formation of pyrimidine dimer and prevent enzyme DNA polymerase from replicating DNA strand beyond site of dimer formation)
- photosensitivity with severe sunburn
- suffer from multiple malignant cutaneous neoplasm at early age