Ciclosporin

- calcineurin inhibitor
- inhibit calcium dependent second messenger signals in T cells following activation via TCR
- inhibits IL-2 production by T-lymphocytes
- adverse effects (4HRT)
  H - hyperkalemia, hypertension, hypertrichosis, hypertrophy of gum
  R - renal toxicity (chronic interstitial nephritis)
  T - tremor

Glucagonoma

- rare alpha cell tumor
- 90% associated with skin rash (necrolytic migratory erythema)
- 70% are malignant, metastasis are common at presentation
- treatment: combination chemotherapy (streptazocin and 5-FU)

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

Diphtheria

- caused by Corynebacterium diphtheriae (Gram positive bacillus)
- produces a toxin which affects myocardium, nervous and adrenal tissues
- most common presentation is with pharyngitis
- areas of grey or white fibrinous exudate coalesce to produce a tough grey-yellow membrane that bleeds when removed (pseudomembrane)
- regional lymphadenopathy produces "bull-neck"
- cutaneous diphtheria may occur, typically ulcer is punched-out with undermined edges covered with a greyish white to brownish adherent membrane
- neuritis frequently follows bulbar distribution
- treatment: anti-toxin (risk of anaphylaxis) and benzylpenicillin 1.2gm QID for 1 week

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

Hyper IgM syndrome

- X-linked defect in CD40 ligand
- B cells are trapped at immature level producing only IgM
- Levels of other types of immunoglobulin are low/absent
- Opportunistic infections (PCP, cryptosporidium, candida) occurs.

Autoantibodies

- dsDNA : SLE

- anti-histone : drug-induced lupus

- anti-centromeric : limited scleroderma

- anti-Ro (SS-A) : SLE, primary Sjogren (anti-Ro only= SLE)

- anti-La (SS-B) : SLE, primary Sjogren

- anti-Sm : SLE

- anti-RNP : SLE, MCTD

- anti-Jo : polymyositis, dermatomyositis

- anti-Scl70 (topoisomerase 1) : diffuse scleroderma

Serotonin syndrome

- toxic hyperserotonergic state can be caused by ingestion of 2 or more drugs that increase serotonin levels (eg: SSRI with MAOI, dopaminergic drug or TCA)
- presents with agitation, confusion, tremor, diarrhea, tachycardia, hypertension and hyperthermia
- treatment: supportive,removal of causative agent, drugs with serotonin antagonist activity (cyproheptadine, methysergide)