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Chapter 19: Fever and Rash

Authors: Elaine T. Kaye; Kenneth M. Kaye

Introduction

  • Fever and rash often present a diagnostic challenge.
  • The combination of rash appearance and clinical syndrome can aid in prompt diagnosis and treatment.
  • Representative images of many rashes are available in Chapter A1.

Approach to the Patient with Fever and Rash

  • History should include:
  • Immune status
  • Medications taken within the previous month
  • Travel history
  • Immunization status
  • Exposure to pets and other animals
  • Animal bites, including arthropod bites
  • Dietary exposures
  • Cardiac abnormalities
  • Prosthetic material presence
  • Exposure to ill individuals
  • Sexual exposures
  • Site of rash onset, direction, and rate of spread

Physical Examination

  • Assess and define salient features of the rash.
  • Determine the type of lesions:
  • Macules: Flat lesions with color change (blanchable erythema)
  • Papules: Raised, solid lesions <5 mm in diameter
  • Plaques: Lesions >5 mm with flat, plateau-like surface
  • Nodules: Lesions >5 mm with rounded configuration
  • Wheals (urticaria/hives): Pale pink papules or plaques, may appear annular
  • Vesicles: Elevated lesions containing fluid (<5 mm)
  • Bullae: Fluid-containing lesions (>5 mm)
  • Pustules: Raised lesions with purulent exudate
  • Purpura:
    • Nonpalpable purpura: Flat lesions due to bleeding into the skin
    • Petechiae: <3 mm
    • Ecchymoses: >3 mm
    • Palpable purpura: Raised lesions due to vasculitis with hemorrhage
  • Ulcers: Skin defects extending into the upper dermis
  • Eschar: Necrotic lesion covered with black crust
  • Note other features:
  • Configuration: Annular, target-shaped, etc.
  • Arrangement of lesions
  • Distribution: Central (trunk) or peripheral (extremities)

Classification of Rash

  • Rashes are classified based on lesion morphology and distribution.
  • Categories include:
  • Centrally distributed maculopapular eruptions
  • Peripheral eruptions
  • Confluent desquamative erythemas
  • Vesiculobullous or pustular eruptions
  • Urticaria-like eruptions
  • Nodular eruptions
  • Purpuric eruptions
  • Eruptions with ulcers or eschars

Centrally Distributed Maculopapular Eruptions

  • Measles (Rubeola):
  • Rash starts at hairline, moves downward
  • Discrete erythematous lesions become confluent
  • Koplik's spots: White or bluish lesions with erythematous halo on buccal mucosa
  • Rubella (German Measles):
  • Rash spreads from hairline downward, may clear as it migrates
  • May be pruritic
  • Forchheimer spots: Palatal petechiae (nonspecific)
  • Postauricular and suboccipital adenopathy
  • Risk to pregnant women due to congenital abnormalities
  • Erythema Infectiosum (Fifth Disease):
  • Caused by human parvovirus B19
  • "Slapped cheeks" appearance with perioral pallor
  • Lacy reticular rash on trunk and extremities
  • May cause arthritis in adults; risk of fetal hydrops in pregnancy
  • Exanthem Subitum (Roseola):
  • Caused by human herpesvirus 6 or 7
  • Rash appears after fever subsides
  • Rose-pink macules and papules starting on the trunk
  • Drug-Induced Eruptions:
  • Exanthematous reactions mimic viral exanthems
  • Often intensely erythematous and pruritic
  • History of new medications is crucial
  • Rickettsial Illnesses:
  • Epidemic Typhus: Associated with body lice in crowded settings
  • Endemic Typhus and Leptospirosis: Urban environments with rodents
  • Erythema Migrans (Lyme Disease):
  • Single or multiple annular lesions
  • Lesions may persist over a year if untreated
  • Acute Rheumatic Fever:
  • Erythema marginatum: Enlarging and shifting annular lesions
  • Systemic Lupus Erythematosus:
  • Malar rash: Sharply defined erythema on cheeks
  • Various other skin manifestations
  • Still's Disease:
  • Evanescent, salmon-colored rash on trunk and proximal extremities
  • Rash coincides with fever spikes
  • Zika Virus Infection:
  • Pruritic rash, often with conjunctival injection
  • Concern for severe congenital defects in pregnancy

Peripheral Eruptions

  • Rocky Mountain Spotted Fever:
  • Lesions evolve from macular to petechial
  • Start on wrists and ankles, spread centripetally
  • Involve palms and soles later
  • Secondary Syphilis:
  • Generalized rash, prominent on palms and soles
  • Consider in sexually active patients
  • Chikungunya Fever:
  • Maculopapular eruption with severe polyarticular arthralgias
  • Hand-Foot-and-Mouth Disease:
  • Tender vesicles on hands, feet, and mouth
  • Caused by coxsackievirus A16 or enterovirus 71
  • Erythema Multiforme:
  • Target lesions on elbows, knees, palms, soles, face
  • May involve mucosal surfaces in severe cases
  • COVID-19 Related Lesions:
  • Pernio-like lesions (chilblains) on feet
  • Vesicles, urticaria, or maculopapular eruptions on trunk and extremities
  • Retiform purpura in severe cases

Confluent Desquamative Erythemas

  • Scarlet Fever:
  • Follows streptococcal pharyngitis
  • Facial flush, "strawberry" tongue, Pastia's lines
  • Kawasaki Disease:
  • Pediatric disease with fissured lips, strawberry tongue, conjunctivitis, adenopathy
  • May involve cardiac abnormalities
  • Toxic Shock Syndromes:
  • Streptococcal: Associated with severe group A streptococcal infection
  • Staphylococcal: Often due to colonization rather than severe infection
  • Both present with hypotension and multiorgan failure
  • Staphylococcal Scalded-Skin Syndrome:
  • Generalized erythema with skin tenderness
  • Nikolsky's sign: Bullae formation with gentle pressure
  • Seen primarily in children and immunocompromised adults
  • Toxic Epidermal Necrolysis:
  • Sloughing of entire epidermis
  • Severe variant of Stevens-Johnson syndrome
  • Exfoliative Erythroderma Syndrome:
  • Associated with eczema, psoriasis, drug reactions, or mycosis fungoides
  • DRESS Syndrome:
  • Drug reaction with eosinophilia and systemic symptoms
  • Often due to antiepileptic or antibiotic agents
  • Multiorgan failure with ~10% mortality

Vesiculobullous or Pustular Eruptions

  • Varicella (Chickenpox):
  • Pruritic lesions in different stages of development
  • Lesions are more prominent on the trunk
  • Pseudomonas "Hot-Tub" Folliculitis:
  • Pruritic lesions after bathing in contaminated hot tubs or pools
  • Lesions occur in areas occluded by bathing suits
  • Variola (Smallpox):
  • Lesions at the same stage of development
  • Most prominent on face and extremities
  • Herpes Simplex Virus Infection:
  • Grouped vesicles on an erythematous base
  • Primary infection accompanied by fever and toxicity
  • Rickettsialpox:
  • Vesicles followed by pustules with papule/plaque base
  • Eschar at site of mite bite
  • Acute Generalized Exanthematous Pustulosis:
  • Sudden onset pustular eruption due to medications
  • Disseminated Vibrio vulnificus Infection or Ecthyma Gangrenosum:
  • Hemorrhagic bullae in immunosuppressed patients with sepsis
  • Mycoplasma-Induced Rash and Mucositis (MIRM):
  • Vesiculobullous eruption with prominent mucositis in children

Urticaria-Like Eruptions

  • Urticarial Vasculitis:
  • Lesions last 3–5 days (longer than classic urticaria)
  • Causes include serum sickness, connective tissue diseases, infections
  • Malignancy-Associated Urticaria:
  • Chronic urticaria with fever may indicate lymphoma

Nodular Eruptions

  • Disseminated Candidiasis:
  • Triad of fever, myalgias, and eruptive nodules
  • Often due to Candida tropicalis
  • Disseminated Cryptococcosis:
  • Lesions resemble molluscum contagiosum
  • Necrotic Nodules:
  • Suggestive of aspergillosis or mucormycosis
  • Erythema Nodosum:
  • Tender nodules on lower extremities
  • Sweet Syndrome:
  • Multiple nodules and plaques, often edematous
  • Associated with infection, inflammatory bowel disease, malignancy, or drug-induced

Purpuric Eruptions

  • Acute Meningococcemia:
  • Petechial eruption, may start as blanchable macules or urticaria
  • Purpura Fulminans:
  • Large ecchymotic areas due to severe disseminated intravascular coagulation
  • Chronic Meningococcemia:
  • Varied lesion morphology, may resemble erythema nodosum
  • Disseminated Gonococcemia:
  • Sparse hemorrhagic pustules near joints
  • Viral Hemorrhagic Fever:
  • Consider in patients with appropriate travel history
  • Thrombotic Thrombocytopenic Purpura and Hemolytic-Uremic Syndrome:
  • Noninfectious causes of fever and petechiae
  • Cutaneous Small-Vessel Vasculitis:
  • Presents as palpable purpura

Eruptions with Ulcers or Eschars

  • Eschar Presence:
  • Suggests Scrub Typhus or Rickettsialpox in appropriate settings
  • Anthrax may present with an ulcer or eschar as the only skin manifestation

Note: This guide is structured for quick revision, highlighting key points and terminology related to fever and rash as discussed in the provided context.