Rash R21.x0

Exanthem" (from Gr. exantheo I blossom) refers to a group of infectious and non-infectious, inflammatory, temporary "skin rashes". Exanthemas are characterized by a dynamic, relapsing course (either one episode or several episodes). They appear generalized or disseminated over larger areas, usually symmetrical(rubella, measles), rarely asymmetrical distribution (example: exanthema, unilateral laterothoracic in childhood). Exanthema is composed of different types of efflorescences (urticae, papules, vesicles, pustules). The dominant type is considered in a more detailed clinical description in the name: urticarial exanthema, macular exanthema, pustular exanthema and so on. If an exanthema course is characterized by multiple episodes, a "colorful" clinical aspect with different efflorescence types may occur (example: varicella exanthema).

• Viral exanthema - normal immunocompetence (see also Viral exanthema):
  • measles (measles virus = paramyxovirus)
  • Rubella (rubella virus)
  • Ringworm ( Erythema infectiosum) (Parvovirus B19)
  • Exanthema subitum (HHV-6, HHV-7)
  • Mononucleosis, infectious (Epstein-Barr virus)
  • Pityriasis rosea (HHV-6, HHV-7)
  • Adenovirus exanthema
  • Unilateral laterothoracic exanthema (virus is not known: influenza virus, EBV, HHV-6, HHV-7 are discussed)
  • Exanthema, asymmetric, periflexural (virus?)
  • Enterovirus exanthema
  • exanthema in coxsackie virus infections
  • Exanthema in echovirus infections
  • Exanthema in rota virus infections
  • Exanthema in Hanta virus infections
  • Hand-foot-and-mouth disease (Coxsackie virus A16, less commonly A5, A7, A9, A10, B1-3, B5, and enterovirus 71)
  • Glove-sock syndrome (parvovirus B19, HHV-6 and HHV-7, CMV?, measles virus?).
• Viral exanthema (vesicular) - normal immunocompetence:
  • Varicella
  • Fever, hemorrhagic (RNA viruses from 4 families).
• Viral exanthema (maculo-papular/vesicular) - impaired immunocompetence:
  • HIV-associated exanthema (in at-risk group).
  • cytomegalovirus infections (in immunosuppression)
  • Eccema herpeticatum (HSV) (in atopic eczema)
  • Zoster generalisatus (varicella zoster virus) (in immunosuppression).
• Bacterial and other infectious exanthema:
  • Bacterial and other infectious exanthema (moderately common):
    • Scarlet fever (Streptococcus pyogenes toxin).
    • Syphilis (Treponema pallidum).
    • Staphylococcal scarlet fe ver (Staphylococcus aureus toxins)
    • Toxic shock syndrome (Staphylococcus aureus toxins)
    • Lyell syndrome
    • Lyme disease (Borrelia spp.).
  • Bacterial and other infectious exanthems (rare):
    • Mycoplasma exanthema
    • Septic diseases with skin manifestations ( gonorrhea, meningococcal meningitis, bacterial endocarditis).
    • Rickettsial diseases ( spotted fever, febris quintana; tenth-day fever, etc.)
    • cat scratch disease (Bartonella henselae)
    • Psittacosis (Chlamydia psittaci)
    • Brucellosis (Bruzella spp.)
    • Q fever (Coxiella burneti)
    • Toxoplasmosis, exanthematous
    • M. Weil (Leptospira icterohaemorrhagica)
    • Listeriosis (Listeria monocytogenes)
    • Paratyphoid fever (Salmonella paratyphi)
    • Typhoid fe ver (Salmonella typhi).
• Parainfectious exanthema/enzyme defects (by frequency):
  • Erythema exsudativum multiforme
  • Pityriasis lichenoides et varioliformis
  • Pityriasis lichenoides chronica
  • Schönlein-Henoch purpura
  • Leukocytoclastic vasculitis (see vasculitis below)
  • Chronic pigmentary purpura
  • Id reactions to candidiasis or trichophytiasis
  • Unilateral laterothoracic exanthema
  • Erythema anulare centrifugum
  • Gianotti-Crosti syndrome
  • Infantile acute hemorrhagic edema
  • Kawasaki syndrome
  • Infantile acrolocalized papulo-vesicular syndrome
  • Erythema gyratum repens
  • Anular lichenoid dermatitis of the adolescent
  • Dermatitis, exudative discoid lichenoid
  • Id reactions to tuberculosis (tuberculids) or leprosy
  • postvaccinal exanthema
  • exanthema in trichinosis
  • carboxylase defect, multiple (rare, in infants)
  • Mediterranean fever, familial (periodic fever syndrome)
  • Muckle-Wells syndrome.
• Allergic/pseudoallergic:
  • Urticarial, lichenoid, maculo-papular, acneiform drug eruptions.
  • Acute or chronic urticaria
  • Contact allergic eczema with exanthematous scattering reactions
  • Urticarial exanthema after insect stings (e.g. wasp venom)
  • Erythema neonatorum.
• Idiopathic or neoplastic:
  • Acute or chronic urticaria
  • Urticarial vasculitis
  • Hypereosinophilic dermatitis
  • Dermatosis, acute febrile neutrophilic (Sweet's syndrome).
  • Exanthematous cutaneous T-cell lymphomas
  • Leukemias of the skin
  • Castleman's lymphoma
  • Pustuloderma, toxic
  • Psoriasis vulgaris (exanthematous)
  • Pustulosis, subcorneal (Sneddon-Wilkinson)
  • Lichen planus
  • Lichen nitidus
  • Histiocytoma, generalized eruptive
  • Dermatoarthritis, familial histiocytic
  • Erythema scarlatiniforme desquamativum recidivans (?).
• Exanthema in rheumatic diseases:
  • CINCA syndrome (periodic fever syndrome).
  • Tumor necrosis factor receptor-associated periodic syndrome (periodic fever syndrome)
  • Erythema anulare rheumaticum
  • Still syndrome
  • Still syndrome, adult (AOSD).
• Autoimmunologic:
  • Blistering autoimmune diseases
  • Pemphigoid gestationis
  • Graft-versus-host disease, acute
  • Dermatitis herpetiformis
  • Systemic lupus erythematosus
  • Subacute cutaneous lupus erythematosus
  • Dermatomyositis
  • Cold urticaria
  • Polyarteritis nodosa, microscopic.
• Toxic:
  • Herxheimer reaction
  • TEN.
• Pseudoexanthema due to external infections:
  • Pseudomonas folliculitis (whirlpool dermatitis).
  • Microsporiasis (generalized)
  • Pityrosporum folliculitis of the infant
  • Cercarial dermatitis
  • Trombidiosis
  • Harlequin discoloration (transient exanthema in infants).

Due to their morphology, some exanthema are characteristic of certain viral and bacterial infections (measles, scarlet fever). Others accompany as "parainfectious" exanthems various infectious diseases (e.g. Gianotti-Crosti syndrome). Exanthema also occurs in allergic, pseudoallergic and rheumatic diseases. Exanthems can be classified according to their etiology:

• • Infectious exanthema
    • Viral exanthema (most common form of exanthema in children)
    • Bacterial and other infectious exanthema
  • Parainfectious exanthema/enzyme defects
  • Allergic/pseudoallergic exanthema
  • Idiopathic exanthema
  • Exanthema for rheumatic diseases
  • Autoimmunological exanthema
  • Toxic exanthema
  • Pseudoexanthema caused by external infections

• neonatal exanthema
• Exanthema in pre-school and school age
• Adult exanthema.

• When assessing an exanthema, the first and most important step towards a valid diagnosis is the basic distinction between an infectious and a non-infectious exanthema. Careful analysis of signs of infection such as fever, AZ disorder, lymphadenopathy, hepatosplenomegaly, blood count and the evaluation of an infection scenario can help here. Only after exclusion of an infectious exanthema can a non-infectious exanthema be considered. The most frequent infectious exanthema are viral exanthema.

1. Föster-Holst R (2007) Virus exanthema. dermatologist 55: 804-817