Mastering Paediatric Fever and Rash for PLAB 2 Success: A Mock Guide
- Ann Augustin
- Jun 15
- 4 min read
When a child presents with fever and rash, identifying the pattern of fever and the type of rash can offer valuable diagnostic clues. Here's a compact guide covering key conditions, fever patterns, rashes, lymph node involvement, and eye findings commonly seen in paediatrics.
🔥 Fever Patterns & Their Clinical Associations
Fever Pattern | Associated Conditions |
Continuous- Temperature remains high with minimal fluctuations (<1°C) throughout the day. | Typhoid (late phase), Kawasaki disease, UTI, pneumonia |
Remittent- Daily temperature varies by >1°C but never returns to normal. | Endocarditis, rheumatic fever, brucellosis |
Intermittent- Fever spikes are followed by periods of normal temperature. | Malaria, sepsis, miliary TB |
Relapsing- Episodes of fever are separated by afebrile periods of several days. | Relapsing fever (Borrelia), lymphoma, malaria |
Undulant- Fever rises and falls gradually over days or weeks. | Brucellosis, Hodgkin lymphoma |
Saddleback- Biphasic pattern with fever, then defervescence, followed by another fever spike. | Dengue, yellow fever |
Step-ladder- Fever gradually increases day by day, reaching a sustained high. | Typhoid (early phase) |
Hectic- Very high daily spikes with sweating and chills, often seen in abscesses or miliary TB | Abscess, TB, sepsis |
Periodic (syndromic)- Recurrent, self-limiting fever episodes at regular or irregular intervals due to autoinflammatory syndromes. | PFAPA(Periodic Fever, Aphthous stomatitis, Pharyngitis, and Adenitis), FMF(Familial Mediterranean Fever), TRAPS(TNF Receptor Associated Periodic Syndrome) |
Kawasaki Disease presents with persistent, high-grade continuous fever lasting ≥5 days, unresponsive to antipyretics.
🌈 Common Paediatric Rashes & Causes
Rash Type | Key Conditions |
Maculopapular- A rash made up of both flat (macules) and raised (papules) red spots. It is uniform in appearance across the body. | Measles, Rubella, Roseola, Fifth Disease (Parvovirus B19) aka Slapped Cheek Syndrome, drug eruptions |
Vesicular- Small, fluid-filled blisters on red or normal skin, may rupture or crust. | Chickenpox, Herpes simplex, Hand-foot-mouth disease (Coxsackie) |
Sandpaper-like- Fine, rough-textured rash that feels like sandpaper to touch. | Scarlet fever |
Polymorphous- Means "many forms" — a rash that includes different types of lesions: macules, papules, urticarial plaques, or morbilliform (measles-like) rash — but not vesicles or bullae. | Kawasaki disease |
Petechial/Purpuric- Non-blanching red or purple spots caused by bleeding under the skin. | Meningococcal septicaemia, ITP, HSP, leukaemia |
Desquamating- Peeling or shedding of the outer skin layer, often after an illness. | Kawasaki (fingers/toes), Scarlet fever, SSSS (Staphylococcal Scalded Skin Syndrome) |
Urticarial- Raised, itchy, red wheals that appear suddenly and may move or fade quickly. | Allergy, viral infections |
👁️ Conjunctivitis in Paediatrics
Condition | Type of Conjunctivitis |
Measles | Bilateral, non-purulent |
Adenovirus | Watery, red eyes, preauricular nodes |
Kawasaki disease | Bilateral, non-purulent |
Ophthalmia neonatorum | Gonococcal (purulent), Chlamydial (mucopurulent), chemical |
Allergic conjunctivitis | Bilateral, itchy, watery |
🦠 Cervical Lymphadenopathy: Unilateral vs Bilateral
Unilateral | Bilateral |
Kawasaki disease, bacterial lymphadenitis | Viral URTIs, EBV, Rubella, Scarlet fever |
Cat scratch disease, TB, malignancy | HIV, autoimmune disease, infectious mononucleosis |
⚖️ Kawasaki Disease vs Scarlet Fever: Key Differences
Feature | Kawasaki Disease | Scarlet Fever |
Cause | Immune-mediated (unknown) | Group A Streptococcus |
Fever | ≥5 days, continuous, unresponsive | High, improves with antibiotics |
Rash | Polymorphous, diffuse | Sandpaper-like, spares perioral area |
Conjunctivitis | Bilateral, non-purulent | Absent |
Lips/Mouth | Cracked lips, strawberry tongue | Strawberry tongue only |
Lymphadenopathy | Unilateral (>1.5 cm) | Bilateral anterior cervical |
Desquamation | Fingers/toes (late phase) | Hands and feet (later stage) |
Complications | Coronary artery aneurysm | Rheumatic fever, glomerulonephritis |
🧠 Summary Pearls for Exams & Clinics
Koplik spots = pathognomonic for Measles
Forchheimer spots = most commonly seen in Rubella, but not specific. Also seen in Scarlet Fever, Infectious Mononucleosis (EBV), Roseola infantum (HHV-6)
Strawberry tongue in both Kawasaki and Scarlet Fever—context is key
Non-blanching rash = meningococcal septicaemia until proven otherwise
Fever + cracked lips + eye redness + swollen extremities = think Kawasaki
Specific or Characteristic Findings in Common Paediatric Illnesses
🦠 Infectious Mononucleosis (EBV)
Posterior cervical lymphadenopathy (often bilateral)
Marked tonsillar enlargement with white/grey exudates
Splenomegaly (risk of rupture → avoid contact sports)
Fatigue that may last weeks
Atypical lymphocytes on blood smear
Positive Monospot test (not reliable in <4 years)
😷 Scarlet Fever (Group A Strep)
Sandpaper rash → rough texture, starts on chest/groin
Circumoral pallor → flushed face with pale area around mouth
Pastia’s lines → accentuation of rash in skin creases (e.g., axilla, groin)
Strawberry tongue (initial white coating → red prominent papillae)
Sore throat with exudates, tender anterior cervical lymph nodes
❤️ Kawasaki Disease
Bilateral non-purulent conjunctivitis (no discharge)
Cracked, red lips and "strawberry" tongue
Extremity changes: Erythema, swelling, and periungual desquamation (peeling fingers/toes)
Polymorphous rash (non-vesicular, varies in appearance)
Unilateral cervical lymphadenopathy (>1.5 cm)
Coronary artery aneurysms (seen on echocardiography in untreated cases)
👁️ Measles (Rubeola)
Koplik spots → tiny blue-white spots on buccal mucosa opposite molars (early clue)
3 Cs: Cough, Coryza, Conjunctivitis
Maculopapular rash: Starts on face behind ears, spreads downward (cephalocaudal)
Rash darkens and may desquamate as it fades
Rash appears ~3–4 days after fever, which peaks with rash onset
🟢 Chickenpox (Varicella)
"Crops of lesions" in different stages: macules, papules, vesicles, pustules, crusts — all at once
Lesions start on trunk, then spread to face/scalp/extremities
Itchy, clear fluid-filled vesicles ("dew drop on a rose petal")
May have low-grade fever before rash
Mild disease in children, but risk of secondary bacterial infection
high yield 👍