Generalised dermatoses

Disseminated viral infections

• Infectious exanthems
  • Most commonly morbilliform cutaneous eruptions
  • Mostly adenvirus, EBV, CMV, coxsackievirus and echovirus, HBV, HHV-6, paramyxovirus, RSV, rotavirus, rubella and HIV
  • Erythematous maculopapular rash is often central, sparing palms and soles
  • Less often petechiae and vesicles can develop
  • Skin lesions usually resolve within 5-7 days

Disseminated gonococcal infection

• 0.5-3% of mucosal genitourinary infections develop dissemination
• Risk factors include late pregnancy, immediate post-partum period and within 1 week of onset of menses
• Fever, arthralgias, multiple papular/vesicular/pustular skin lesions
• Rash develops on extensor surfaces of wrist, palms, hands and ankles/feet
• Usually <20 lesions, small red papules with petechial component on erythematous base
• Lesions resolve rapidly or turn into vesicles with necrotic centres
• Ultimately lesions become haemorrhagic
• Usually not systemically unwell

• DDx includes other petechial syndromes
  • Meningococcaemia
  • Infective endocarditis
  • Vasculitidies
  • HSP
  • Leukocytoclastic vasculitis
  • Enteroviral infection
  • Bacterial sepsis
  • DIC
  • Typhus
• Reiter syndrome differs in that it involves urethritis, conjunctivitis and arthritis with psoriasis-like cutaneous eruption vs. petechiae/macules/papules

• Diagnosis is in sexually active adult with tenosynovitis/arthralgias and dermatological findings
• Gram staining of fluid from deroofed lesions demonstrates N. gonorrhoeae
• BC may be positive (higher yield in early phase)
• Can culture urethral, cervical, pharyngeal swabs
  • Although usually sterile in disseminated disease
• Treatment
  • Ceftriaxone 1g IV daily for 7 days

Meningococcaemia

• Dermatological manifestations include petechiae, urticaria, haemorrhagic vesicles, macules and/or maculopapules
• Classic petechial lesions on extremities and trunk but also on palms, soles, head and mucous membranes
• Petechiae evolve into palpable purpura with grey necrotic centres (pathognomonic)
• Fulminant meningococcal disease presents with sudden prostration, petechiae with areas of ecchymosis and shock
  • Often complicated by purpura fulminans, a severe form of DIC
  • Extremities become gangrenous and necrotic

Purpura fulminans

• Rare vascular disorder
• Fever, shock, multi-organ failure and rapid haemorrhagic skin necrosis
• Associated with vascular collapse and DIC
• Can result from acquired Protein C deficiency, activated protein C resistance or Protein S deficiency or any cause of DIC
• Triad of: Widespread ecchymoses, haemorrhagic bullae and epidermal necrosis

Pemphigus vulgaris

• Generalised, mucocutaneous, autoimmune blistering eruption with a grave prognosis
• Suffer large flaccid bullae, Nikolsky positive, ulcerations, exfoliations and mucous membrane involvement
• Head, trunk and mucous membranes first
• Mostly 50-60yo
• Admission for aggressive fluid support, corticosteroid/immunosuppressive therapy is required

Specific viral exanthems

• Varicella
• Morbilli
• Rubella
• Roseola
• Erythema infectiosum
• Hand, foot and mouth
• Pityriasis rosea
• Gianotti Crosti syndrome
• Laterothoracic exanthem

Varicella

• Predominantly face and trunk
• Arise in crops
• Highly contagious from 1-2 days prior to eruption
• Spread by airborne droplets and blister fluid
• Incubation period 10-21 days
• Moderate to high fever, URTI, malaise
• Complications (mostly adults): Pneumonitis, Cerebellitis, thrombocytopaenia, streptococcal cellulitis

Measles

• Measles is highly contagious from 2 days prior to symptoms and 5 days after onset of rash
• Spread by airborne droplets
• Incubation period 7-14 days
• Prodromal fever, malaise, anorexia, conjunctivitis, cough and coryza
• Koplik spots 2-3 days into prodrome then 1-2 days later rash appears
• Rash starts on cheeks and spreads out
• Fades within days
• Cough persists 1-3 weeks
• Complications: Otitis media, corneal ulceration, GN, pneumonitis, sepsis

Rubella

• Mild febrile illness, lymphadenopathy and pale pink erythema
• Contagious from 7 days prior to rash and 7 days after
• Spread by direct contact with throat secretions
• 25-50% of cases are asymptomatic
• Rash begins on face and spreads out
• Lasts up to 5 days

Roseola infantum

• Herpes virus 6 +- 7
• Mostly children aged 6 months to 3 years
• High fever (common cause of febrile convulsion)
• Rhinitis, cough, irritability, tiredness
• As fever subsides, rash appears on face and trunk
• Rash lasts 1-3 days
• Spread via droplets

Erythema infectiosum

• Parvovirus B19 (slapped cheek disease/Fifth disease)
• Mostly young children
• Slight fever, headache and flushed cheeks
• Occasionally get erythema in glove/stocking distribution
• Arthralgia in adults and rarely aplastic crises

Hand, foot and mouth

• Coxsackie virus A16 and Enterovirus 71
• 3-5 day incubation, blistering illness
• May be mild fever
• Main concern is mouth lesions limiting oral intake

Pityriasis rosea

• Human herpes virus 6/7
• Mostly teenagers and young adults
• Solitary oval herald patch appears 1-2 weeks before eruption of smaller plaques in fir tree pattern on trunk
• Resolves over 6-12 weeks
• Itching can be treated with topical steroids

Gianotti Crosti syndrome

• Aka Papulovesicular acrodermatitis, papular acrodermatitis of childhood and acrodermatitis papulosa infantum
• Arises in children 6 months to 12 years old
• Persists 2-8 weeks
• Causes include HBV, EBV, Coxsackie, Echovirus and RSV
• Over 3-4 days get profuse eruption of erythematous macules, papules, plaques on thighs/buttocks, then outer aspects of arms then face
• Often asymmetrical and not particularly itchy

Laterothoracic exanthem

• Uncommon rash affecting young girls mostly
• Thought to be viral in origin
• Armpit or groin gradually extending outwards on one side of body
• Can persist for 12 weeks
• Tiny papules coalesce into dry plaques

Prurigio

• Intensely itchy spots
• Primary lesions are dome-shaped papules
• Secondary lesions are scratched or thickened darkly pigmented spots
• Prurigo simplex
  • Symmetrically distributed tiny pruritic dome-shaped bumps. May be tiny blisters
  • Most numerous on limbs and buttocks
  • Often primary papules are no longer visible as scratched off
• Nodular prurigo
  • Hard, warty nodules with pigmentation
• Associations
  • Atopic eczema
  • Bullous pemphigoid
  • Iron deficiency
  • Thyroid disease
  • HIV
  • Pregnancy
  • Chronic renal failure
  • Diabetes mellitus
  • Hodgkin or NHL
  • Amphetamine/cocaine use

Last Updated on October 13, 2021 by Andrew Crofton