Rash - ACEM Fellowship Notes

#paeds #infectious_diseases see: [bear rashes](bear://x-callback-url/open-note?id=66A1CF75-1B26-4BE2-99FC-84BEC103CB25-34582-00008F9245D58F4A) see also: [[Henoch-Schonlein Purpura|HSP]], [[measles]], [[Kawasaki Disease]], [[SJS and TENs]] see: [Hayes' SJS and TEN](x-devonthink-item://9D454E32-8E85-4067-A299-6D2DC1ECB185) > [!DDx paeds rash]- > - red and scaly rashes > - eczema/seborrheic dermatitis > - psoriasis > - neonatal SLE > - syphilus > - ichthyosis - autosomal recessive congenital ichthyosis > - immunodefficiency > - pustular > - infections > - s aureus > - group A srep > - candida > - benign inflammatory causes > - erythema toxicum > - neonatla cephalic pustulosis > - eosinophilic pustular folliculitis > - miliaria (heat rash) > - vesicles and bullae > - infections > - varicella > - HSV > - s aureus (impetigo, pustules, staphylococcal scalded skin syndrome) > - genetic - epidermlysis bullosa > - inflammatory > - miliaria (heat rash) > - langerhans cell histocytosis > - mastocytosis > - autoimmune > - arthropod > - scabies > - bed bugs > - fleas > - other insects > - traumatic -- burns and scalds > - birthmarks > - epidermal naevia > - vascular lesions > - transient - cutis marmorata, harlequin colour change > - macular - salmon patch, capillary malformation, early haemangioma > - palpable - haemangioma of infancy, vascular malformations, other vascular tumours > - brown/black > - naevi > - dermal melanocytosis (mongolian spot) > - blue/purple lesions > - dermal melanocytosis > - congenital infection > - rubella > - toxoplasmosis > - CMV > - HSV > - etc > - tumours - congenital leukaemia cutis, neuroblastoma, langerhans cell histiocytosis > - purpura > - bruising -- trauma, bleeding disorder, [[haemolytic disease of newborn]] > - vascular tumours or malformations > - s/c fat necrosis of newborn > **Rash description:** > 1. appearance > 2. distribution (eg dermatomal, cross midline) > 3. special features # Blistering rashes ## erythema multiforme - erythema multiforme, stevens-johnson syndrome (SJS), and toxic epidermal necrolysis (TEN) are thought to share a similar immunological mechanism - however, erythema multiforme is considered a separate disease, while SJS and TEN are considered a spectrum of the same disease - prodromal non-specific malaise and fever a few daus - rash first on backs and hands or tops of feet, spread along the limbs towards trunk - upper limbs > lower limbs - can be macules, papules, wheals, vesicle,s bullae - **target lesions** are diagnostic **causes** - *infections* cause 90% of cases - HSV - mycoplasm - varicella (chickenpox) - adenovirus - hepatitis - CMV - viral vaccines - drugs - <10% of cases (more commonly cause SJS) - penicillins - sulfa - carbamazapine - NSAIDS - lamotrigine - allopruinol ## SJS / TEN see also: [[SJS and TENs]] > - an immune-complex–mediated hypersensitivity reaction. > - Not just “bad erythema multiforme” > - involvement with **2 or more mucosal surfaces** (usually **eyes** and mouth) → conjunctivitis may be presenting issue! - drugs (90% of cases in adults) - more common if HIV also present - anticonvulsants: lamotrigine, carbamaepine, phenytoin - NSAIDS - antimicrobials: sulfa, penicillins, cephalosporins, TMP - omeprazole - allopurinol - HIV - lymphoma / leukema - The commonest infection associated with SJS is *Mycoplasma pneumonia*, particularly in *children*. - onset *within 1 week of abx therapy* or 1 month of anticonvulsant therapy - onset can help differentiate it from DRESS - prodrome illness a few days prior to rash: sore throat, fever - full thickness epidermal necrosis - rash starts on trunk -- extends rapidly over hours to days onto face and limbs - rarely affects scalp, palms, or soles - **large flaccid bullae which rapidly desquamate** (+ve Nikolsky sign) - mucous membranes often involved **classification** - SJS - area of skin detachment <10% TBSA - erythematous or purpuric macules or flat atypical targets - SJS/TEN - 10-30% TBSA - TEN with spots - area of detacment > 30% TBSA - TEN without spots - area of detachment >10% TBSA - large epidermal sheets and no purpuric macules **investigations** - *skin biopsy *required* - ==only definitive diagnostic investigation== - look for keratinocyte aka *epidermal necrosis* - [[Anaemia]] usually present - lymphopaenia - neutropenia sign of poor prognosis - eosinophilia does not appear **Treatment** - stop agent - protect patient from hypothermia as with burns - sterile handling - ppx abx not recommended, but ↑ risk of infection - wound care eg acticoat Ag - avoid silver sulfadizine if SJS/TEN due to concern of sulfa - ?immunosuppression ? d/w DERM - IVIG - ciclosporin - infliximab - plasmapheresis - ? Ocular steroids? (D/w ophthal/derm) > **SCORTEN Scale** (1 point each) > - age > 40 > - heart rate >120 > - associated malignancy > - serum urea >10 > - detatched or compromised BSA > 10% > - serum HCO3 <20 > - serum glucose > 14 mortality 35% with score of 3, 60% with 4, 90% if >5 ![[Pasted image 20241102165056.png|Toxic epidermal necrolysis]] ![[Pasted image 20241102164912.png]] ## Toxic shock syndrome - colonisation with toxin producing staph aureus - desquamating erythroderma - shock - multiple organ failure - pharyngitis - conjunctiviis ## staph scalded skin - 60% cases children <2 years old - staph aureus phage infexion - may be non-cutaneous - epidermolytic toxin - *no mucosal involvement* - less severe illness than TEN; small skin loss - bloods normal ESR elevated **treatment** - as cutaneous burn - *do NOT give glucocorticoids* - fluclox 50mg/kg (up to 2g) Q6H ## Bullous pemphigoid vs Pemphigus vulgaris "pemphig*oid* is is pemphigus-*oid* aka, it's the less bad one." | | pemphigus vulgaris | bullous pemphigoid | | ---------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------------------------------------------------- | | path | - older adults - type II hypersensitivity reaction ; IgG vs desmoglein - ACE-i may precipitate | - more common than pemphigus - also older - also T2 hypersensitivity IgG vs hemidesmosomes (epidermal basement membrane) | | severity | potentially fatal | less severe than pemphigus | | morphology | - flaccid intraepidermal bullae caused by *acantholysis* (separation of keratinocytes) that *easily rupture* - oral mucosa involved - ==+ve Nikolsky== | - tense blisters containing eosinophils that *rarely rupture* - nothing in oral mucosa - Nikolsky negative | | treatment | - systemic glucocorticoids 1mg/kg - azathioprine 4mg/kg +/- IVIG | - prednisolone 0.5mg/kg od - azathioprine if steroids not working | | example | ![[Pasted image 20241109011001.png]] ![[Pasted image 20241109011538.png]] ![[Pasted image 20241109011613.png]] ![[Pasted image 20241109011626.png]] | ![[Pasted image 20241109011304.png]] ![[Pasted image 20241109011747.png]] | ## DDx for blistering / bullous rash Consider the example from this practice question: ![[Pasted image 20241109011915.png]] ![[Pasted image 20241109011925.png]] bullous forearm with erythematous changes. non-dermatomal; crosses midline. few vesicles. DDx: - pemphigus vulgaris - bullous pemphigoid - disseminated [[Herpes zoster|Varicella zoster]] ## DRESS see: [Hayes' - DRESS syndrome](x-devonthink-item://400C2A4F-2C7D-4167-A36F-4031DBAC5C91) "Drug Rash with Eosinophilia and Systemic Symptoms" - Long latency (2-8 weeks between drug exposure and disease onset - helps distinguish it from SJS and TEN - prolonged course with relapses even after discontinuing drug - associated with HSV infection *causes*: - antiepileptics (carbamazepine, lamotrigine, phenytoin) - abx (sulfa, vanc) - allopurinol *features* - rash 2-8 weeks after starting medication - fever 38-40 - malaise/lethargy - **morbilliform eruption** - *morbilliform* = a rash that looks like measles. - macular lesions that are red and usually 2–10 mm in diameter but may be confluent in places. - rose-red flat or slightly elevated eruption, showing circular or elliptical lesions varying in diameter from 1 to 3 mm, with healthy-looking skin intervening - face and upper part of trunk - progresses to diffuse, confluent infiltrated erythema with follicular accentuation - suggests DRESS when involves >50% of body surface and/or 2 or more of facial oedema, infiltrated lesions, scaling, and purpura ![[Pasted image 20241102164744.png]] ## DRESS vs TENs ![[Pasted image 20241102162323.png]] # other rashes ## amoxicillin rash - common in glandular fever / EBV ## serum sickness see: [[Snakebite#serum sickness]] caused by: - snake antivenom - monoclonal antibiodies like rituximab - insect stings eg bees - antiserum - rabies and tetanus **symptoms**: - fever - rash -- urticarial in flexural areas then more generalised. persist days in same areas, pruritic - polyarthritis - joint pain, limp erythema and oedema in hands and feet common lymphadenopathy **DDx:** - [[#erythema multiforme]] - [[#SJS / TEN]] - urticaria **mgmt:** - stop drugs - +/- steroids # DDx anaphylaxis rashes | | [[anaphylactoid]] | [[#serum sickness]] | [[marine ingestions#Scrombroid poisoning\|Scrombroid]] | | -------- | ----------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------- | | cause | - morphine - NAC - vancomycin - IV contrast | - snake antivenom - monoclonal abs eg rituximab - insect stings eg bees - rabies and tetanus antiserum | - histamine from tuna or mackerel can | | symptoms | | - fever - urticarial rash - polyarthritis - swelling in hands and feet common | - flushing - headache, dizziness - swelling - nausea, vomiting - diarrhoea - abdo pain - occasionally urticaria, pruritis | # Some childhood viral rashes Note: the problem with this table is that it isn't remotely helpful for the actual problem of deciding appropriate tests and disposition and treatments, and therefore is not particularly useful for fellowship study | cause | associated syndrome | clinical features | pic | | ---------------- | ------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------ | | coxsackie A | Hand-foot-mouth disease | - oval-shaped vesicles on palms and soles - vesicles and ulcers in oral mucosa (*herpangina*) | ![[Pasted image 20241107161345.png]] | | HH6 | Roseola | - asymptomatic rose-coloured macules appear on body after several days of high fever - usually affects infants | | | measles | Measles (rubeola) | - confluent rash beginning at head and moving down - preceded by *cough, coryza, conjunctivitis* - may have bloe-white (Koplik) spots on buccal mucosa | | | parvo B19 | Erythema infectiosum (5th disease) | - "slapped cheek" rash on face - can cause *hydrops fetalis* in pregnant women | ![[Pasted image 20241107161620.png]] | | Rubella | Rubella | - pink macules and papules begin at head and move down, remain discrete . progress to fine desquamating truncal rash - postauricular lymphadenopathy | | | Strep pyogenes | Scarlet fever | - flushed cheeks and circumoral pallor on face - erythematous, sandpaper-like rash from neck to trunk and extremities - fever, sore throat, *strawberry tongue* | ![[Pasted image 20241107161756.png]] | | varicella-zoster | chickenpox | - vesicular rash begins on trunk - spreads to face and extremities with lesions of different stages | ![[Pasted image 20241107162023.png]] |