What is the appropriate management for a healthy adult with a 1.5–2 cm mobile, mildly tender, well‑circumscribed scalp nodule on the left posterior scalp near the hairline without overlying skin changes or neurological deficits?

Management of Scalp Nodule

This patient requires close observation with a 2-4 week follow-up rather than immediate aggressive workup, as the lesion does not meet high-risk criteria for malignancy despite its size.

Risk Stratification

The 2017 AAO-HNS guideline for neck masses provides a framework that can be applied to scalp lesions 1. This patient's nodule has one concerning feature (size >1.5 cm) but lacks other high-risk characteristics:

Features Present (Lower Risk):

• Mobile (not fixed to adjacent tissues)
• Well-circumscribed
• No overlying skin changes (no erythema, warmth, ulceration, or bleeding)
• No systemic signs of infection
• No cervical lymphadenopathy
• No neurological deficits

Features Absent (Would Indicate Higher Risk):

• Fixation to underlying structures
• Firm/hard consistency (described as palpable but not specifically firm)
• Ulceration of overlying skin
• Duration ≥2 weeks without fluctuation (duration not specified in presentation)

Initial Management Approach

1. Establish Timeline and Observe

• Document when the patient first noticed the nodule
• If present <2 weeks: Schedule follow-up in 2 weeks to assess for resolution or progression 1
• If present ≥2 weeks or uncertain duration: This increases malignancy risk and warrants closer monitoring 1

2. Patient Education on Red Flags 1

Instruct the patient to return immediately if any of the following develop:

• Rapid growth or change in consistency
• Development of fixation (becomes immobile)
• Overlying skin changes (ulceration, persistent erythema)
• New neurological symptoms
• New systemic symptoms (unexplained weight loss, fever >101°F)
• Development of additional masses

3. Avoid Empiric Antibiotics

Do not prescribe antibiotics unless clear signs of bacterial infection are present 1. This lesion lacks:

• Warmth
• Erythema
• Fluctuance
• Drainage
• Fever or systemic signs of infection

The guideline explicitly recommends against routine antibiotic therapy for masses without infectious signs, as this delays diagnosis and provides false reassurance 1.

When to Escalate Workup

Immediate Imaging Indications:

If the patient meets ≥2 high-risk criteria, order CT or MRI with contrast 1:

• Size >1.5 cm (already present) PLUS
• Firm consistency OR
• Fixed to underlying structures OR
• Duration ≥2 weeks without change OR
• Development of concerning symptoms

Referral Indications:

Consider dermatology or surgical referral if:

• No resolution after 4 weeks of observation
• Progressive growth
• Development of additional high-risk features
• Patient anxiety warrants earlier definitive diagnosis

Most Likely Diagnoses

For scalp nodules in healthy adults, the differential includes 2, 3:

• Epidermoid/pilar cyst (most common benign scalp lesion)
• Lipoma
• Dermatofibroma
• Benign follicular tumors (trichilemmoma, pilomatricoma) 4
• Less likely: metastatic disease (typically in patients with known malignancy) 3

Critical Pitfalls to Avoid

1. Don't assume size alone mandates aggressive workup: The 1.5 cm threshold is one criterion among several. Mobile, well-circumscribed lesions without other concerning features can be observed 1.

2. Don't biopsy prematurely: Open biopsy should be reserved for lesions where malignancy is suspected after appropriate evaluation, not as a first-line diagnostic tool 1.

3. Don't provide false reassurance: Even benign-appearing lesions require documented follow-up to ensure resolution or stable diagnosis 1.

4. Document your plan: Clearly document the follow-up timeline and criteria that would trigger re-evaluation 1.

Follow-Up Protocol

• 2-week reassessment if duration uncertain or <2 weeks at presentation
• 4-week reassessment if clearly present <1 week and stable
• Document size, consistency, mobility, and overlying skin at each visit
• If unchanged at 4-6 weeks and patient desires definitive diagnosis: consider elective excisional biopsy for both diagnosis and treatment
• If any progression or development of high-risk features: proceed to imaging and specialist referral

The key is balancing appropriate vigilance against overtreatment of what is most likely a benign scalp lesion, while maintaining clear safety nets for the patient.