What is the appropriate assessment and management of a scalp lump on an infant?

Assessment of a Scalp Lump in an Infant

Begin with a focused clinical evaluation to distinguish between the most common causes: infantile hemangioma (4-5% of infants), delayed subaponeurotic fluid collection (DSFC), traumatic vascular injury, or infection—each requiring a distinct management pathway. 1, 2

Initial Clinical Assessment

History

• Age at onset: Infantile hemangiomas appear within the first few weeks of life and proliferate rapidly between 5-7 weeks of age 1, 3
• Birth trauma: DSFC is associated with vacuum-assisted delivery, forceps use, or fetal scalp electrodes and manifests after the first few weeks of life 2, 4
• Growth pattern: Rapid or progressive growth suggests malignancy (though rare at 1% of pediatric lumps), hemangioma, or vascular injury 5, 6
• Trauma history: A growing pulsatile lump after blunt head injury suggests pseudoaneurysm or arteriovenous fistula 6
• Systemic symptoms: Fever, purulent drainage, or warmth indicates infection requiring systemic antibiotics 7

Physical Examination Characteristics

For infantile hemangiomas 1, 3:

• Bright red, raised, compressible lesions that blanch with pressure
• Superficial (strawberry appearance), deep (bluish subcutaneous mass), or mixed type
• Segmental morphology (plaque-like) versus localized (focal)
• Size ≥4 cm or ≥2 cm on face (≥1 cm if infant <3 months) indicates high-risk

For DSFC 2, 4:

• Soft, ill-defined, fluctuant, highly mobile swelling
• Not limited by suture lines (key distinguishing feature from cephalohematoma)
• No overlying skin changes, erythema, or warmth
• Well-appearing infant without systemic symptoms

For infection 7:

• Purulent drainage, crusting, erythema, warmth, tenderness
• Fluctuant collection suggests abscess requiring drainage

For vascular injury 6:

• Pulsatile, growing mass after trauma
• Bruit or thrill on palpation

Five malignancy risk factors (though rare) 5:

• Onset in neonatal period
• Rapid or progressive growth
• Skin ulceration
• Fixation to or location deep to fascia
• Firm mass >3 cm diameter

Diagnostic Approach by Clinical Scenario

Suspected Infantile Hemangioma

Most infantile hemangiomas are diagnosed clinically without imaging 1. However, imaging is indicated for:

• Atypical superficial features 1
• Deep lesions difficult to assess physically 1
• Segmental facial or scalp hemangiomas (PHACE syndrome risk ~30%) 1, 3
• Lesions ≥4 cm 1
• Presence of ≥5 hemangiomas (hepatic involvement risk) 3
• "Beard distribution" (airway involvement risk) 1, 3

Imaging modality: Ultrasound with Doppler is first-line for superficial lesions; MRI for deep or segmental lesions requiring PHACE workup 1

Critical action: Urgent specialist referral (pediatric dermatology, vascular anomalies center, or pediatric surgery) is mandatory for any scalp hemangioma, as segmental scalp lesions carry PHACE syndrome risk and optimal treatment window is at 1 month of age 3, 8. Do not adopt a "wait-and-see" approach, as 90% leave permanent skin changes despite involution 8.

Suspected DSFC

If clinical features are characteristic (soft, fluctuant, crosses suture lines, well-appearing infant with birth trauma history), no imaging or laboratory work is necessary 2, 4.

Management: Conservative observation, as DSFC resolves spontaneously without intervention 2, 4. Reassure parents and avoid unnecessary subspecialty consultation or child abuse investigation 2.

Suspected Infection

Culture specimens before initiating antibiotics when possible 7.

For bacterial scalp infections without abscess 7:

• Oral antibiotics targeting Gram-positive organisms (Streptococcus, Staphylococcus aureus)
• Add MRSA coverage if high-risk (prior MRSA, failure of initial therapy, high local prevalence)
• Never use topical antibiotics alone

For scalp abscess 7:

• Incision and drainage is primary treatment
• Add systemic antibiotics only if systemic signs present or immunocompromised
• Never prescribe antibiotics alone without drainage

For gonococcal scalp abscess in newborns (rare, from fetal scalp electrode) 1, 7:

• Ceftriaxone 25-50 mg/kg/day IV or IM for 7 days (10-14 days if meningitis)
• Culture blood, CSF, and joint aspirate

Suspected Traumatic Vascular Injury

Ultrasonography with Doppler is useful for detecting pseudoaneurysm or arteriovenous fistula 6. If confirmed, vascular surgery consultation is required for definitive management.

Uncertain Diagnosis

If any of the five malignancy risk factors are present, proceed with imaging (ultrasound first-line, MRI if deep involvement suspected) and surgical consultation 5. In the absence of all five risk factors, the likelihood of malignancy is 0.3%, and elective excision can be planned for cosmetic reasons or definitive diagnosis 5.

Common Pitfalls to Avoid

• Never reassure families that hemangiomas will simply "go away"—while most involute, they often leave permanent disfigurement, and the therapeutic window is narrow 8
• Never miss PHACE syndrome screening in segmental facial or scalp hemangiomas (30% risk) 1, 3
• Never delay specialist referral for infantile hemangiomas, as optimal treatment timing is at 1 month of age, before peak proliferation at 5-7 weeks 3, 8
• Never order imaging for clinically obvious DSFC—this leads to unnecessary cost, radiation exposure, and parental anxiety 2, 4
• Never rely on topical antibiotics alone for bacterial scalp infections 7