What is the cause and treatment of small fine bumps on a baby's skin?

Small Fine Bumps on Baby Skin

Most small fine bumps on a baby are benign, self-resolving conditions like milia, miliaria (heat rash), or neonatal acne that require only parental reassurance and observation, though specific features may indicate conditions requiring intervention. 1

Initial Assessment Framework

When evaluating small fine bumps on an infant, determine the following key characteristics to guide diagnosis:

Age of Onset

• Before 6 months: Consider mastocytosis, congenital eczema, or transient neonatal conditions 2
• 2-4 weeks of life: Neonatal acne is most common, occurring in 20% of children with male predominance (4.5:1 ratio) 3
• Before 4 weeks: Infantile hemangiomas appear early, with maximum growth completed by 5 months 4, 2

Distribution Pattern

• Trunk and extremities: Suggests mastocytosis (urticaria pigmentosa) 2
• Flexural areas: Characteristic of atopic eczema 2
• Face (forehead, cheeks, chin): Typical for neonatal acne, occasionally spreading to scalp, neck, and trunk 3
• Scalp: Consider tinea capitis, mastocytosis, or infantile hemangiomas 5

Lesion Characteristics

• White or flesh-colored papules: Milia (from immature skin structures) or molluscum contagiosum 1, 6
• Red papules/pustules: Erythema toxicum neonatorum, neonatal acne, or miliaria rubra 1, 3
• Red-brown to yellow lesions with positive Darier's sign: Mastocytosis 2
• Raised vascular lesions with well-defined borders: Infantile hemangiomas 4

Common Benign Conditions

Milia and Miliaria

• Milia: Result from immature skin structures, appear as tiny white papules, resolve spontaneously 1
• Miliaria rubra (heat rash): Improves with cooling measures; avoid overheating and excessive clothing 1

Neonatal Acne

• Presentation: Open and closed comedones evolving into papules and erythematous pustules, rarely nodules/cysts 3
• Pathophysiology: Elevated placental and neonatal androgens cause sebaceous gland enlargement and increased sebum production 3
• Management: Most cases resolve spontaneously; mild dermal cleanser with water is sufficient 3
• For comedogenic lesions: Topical retinoids or 20% azelaic acid may be used 3
• For inflammatory lesions: Topical antibiotics can be considered 3

Erythema Toxicum Neonatorum

• Diagnosis: Clinical diagnosis based on distinctive appearance of transient vesiculopustular rash 1
• Management: Parental reassurance; no treatment needed 1

Conditions Requiring Further Evaluation

Mastocytosis

Test for Darier's sign (stroking lesion causes wheal and flare): Positive result is highly suggestive of mastocytosis 2

Evaluate for systemic symptoms: Flushing, pruritus, abdominal pain, diarrhea, hypotension, respiratory symptoms 2

Emergency signs: Flushing, dyspnea, wheezing, nausea, vomiting, diarrhea, hypotension require immediate intervention 2

Management: Symptomatic treatment with antihistamines and avoidance of mast cell degranulation triggers; monitor for systemic symptoms 5

Infantile Hemangiomas

High-risk features requiring early referral (ideally by 1 month of age): 4

• Facial location (risk of permanent scarring/disfigurement)
• Periorbital location (risk of functional impairment)
• Large size (>5 cm requires screening for PHACE syndrome)
• Segmental lumbosacral hemangiomas (associated with LUMBAR syndrome in up to 55% of cases) 4

Treatment when indicated: Propranolol 2-3 mg/kg/day is the drug of choice, continued for at least 6 months, often until 12 months of age 4

Topical timolol: May be used for select small, thin, superficial hemangiomas 4

Infectious Causes Requiring Urgent Evaluation

Bullous impetigo: Fragile fluid-filled vesicles and flaccid blisters caused by Staphylococcus aureus; requires bacterial culture and antibiotic sensitivities 7

Treatment: Topical fusidic acid as first-line or mupirocin for resistant cases; systemic flucloxacillin for extensive disease 7

Gonococcal scalp abscess: Consider if history of fetal scalp electrode placement; requires blood, CSF, and wound cultures on chocolate agar; treat with ceftriaxone 25-50 mg/kg/day IV or IM for 7 days (10-14 days if meningitis documented) 8

Tinea capitis: Requires mycological confirmation (fungal culture or KOH preparation) and systemic antifungal treatment with terbinafine for Trichophyton species or griseofulvin for Microsporum species 5

Critical Red Flags

Infants who are not well-appearing or have risk factors for congenital infection with pustules or vesicles require further investigation for congenital infections 8

Severe or long-lasting neonatal acne: Requires clinical and paraclinical examination to exclude congenital adrenal hyperplasia or virilizing tumor 3

Avoid assuming all scalp scaling is seborrheic dermatitis: Tinea capitis can present with diffuse scaling without obvious alopecia 5