What could be the cause of two bumps on the scalp with no drainage, accompanied by tingling and burning sensations on the scalp, and a feeling of tightness on the right side of the face?

Herpes Zoster (Shingles) is the Most Likely Diagnosis

The combination of new scalp bumps with tingling, burning sensations, and unilateral facial tightness strongly suggests herpes zoster (shingles) affecting the trigeminal nerve distribution, which requires immediate antiviral treatment to prevent complications including postherpetic neuralgia.

Key Diagnostic Features

The clinical presentation points specifically to herpes zoster:

• Unilateral distribution of symptoms (right-sided facial tightness) is pathognomonic for herpes zoster, which follows dermatomal patterns 1
• Prodromal symptoms of tingling and burning typically precede visible lesions by 1-5 days in herpes zoster 1
• Two bumps without drainage represent early vesicular lesions that have not yet ruptured 1
• Scalp involvement with facial symptoms suggests trigeminal nerve (V1 branch) involvement, which can lead to serious complications 1

Critical Immediate Actions

Start antiviral therapy immediately if herpes zoster is suspected, ideally within 72 hours of symptom onset to reduce severity and prevent postherpetic neuralgia 1. Do not wait for lesion evolution or confirmatory testing.

Examination Priorities

Look for these specific findings:

• Grouped vesicles on an erythematous base following a dermatomal distribution 1
• Sharp midline demarcation - lesions should not cross the midline 1
• Ophthalmic involvement - examine the eye carefully if V1 distribution is affected, as this can cause vision-threatening complications 1
• Hutchinson's sign (lesions on tip of nose) indicates nasociliary nerve involvement and high risk of ocular complications 1

Alternative Diagnoses to Consider

While herpes zoster is most likely, briefly evaluate for:

Folliculitis/Furuncles

• Would present as painful, tender, fluctuant red nodules with surrounding erythema 2
• Typically bilateral and random distribution, not dermatomal 2
• Usually have pustules with visible pus, not just bumps 2
• Lack the burning/tingling prodrome characteristic of herpes zoster 2

Scalp Dysesthesia

• Presents with burning and itching without visible lesions 1, 3
• Associated with diabetes, psychiatric history, or post-infectious states (including COVID-19) 1
• Would not explain visible bumps 3
• Typically bilateral symptoms, not unilateral facial tightness 4

Contact Dermatitis or Sensitive Scalp

• Would show diffuse erythema and scaling, not discrete bumps 3
• Symptoms are bilateral and generalized 4
• No dermatomal pattern 3

Treatment Algorithm

If Herpes Zoster Confirmed or Highly Suspected:

1. Immediate antiviral therapy (within 72 hours of rash onset):

   • Valacyclovir 1000 mg three times daily for 7 days, OR
   • Famciclovir 500 mg three times daily for 7 days
   • These reduce acute pain, accelerate healing, and decrease postherpetic neuralgia risk 1

2. Pain management:

   • Acetaminophen or NSAIDs for mild pain
   • Consider gabapentin or pregabalin for neuropathic pain 1
   • Topical lidocaine patches may provide relief 1

3. Ophthalmology referral if any eye involvement or V1 distribution 1

If Folliculitis/Furuncles:

• Incision and drainage is mandatory for carbuncles or large furuncles 2, 5
• Moist heat application for small furuncles 2
• Antibiotics only if fever, extensive cellulitis, or systemic symptoms present 2, 5
• Do not treat with antibiotics alone without drainage - this will fail 5

Common Pitfalls to Avoid

• Do not wait for classic vesicular rash - prodromal symptoms with dermatomal distribution warrant immediate antiviral treatment 1
• Do not dismiss unilateral symptoms - this is a critical diagnostic clue for herpes zoster 1
• Do not perform incision and drainage if herpes zoster is suspected - there is no pus collection 5
• Do not delay ophthalmology referral if scalp lesions are near the forehead or eye 1
• Do not attribute symptoms to stress or sensitive scalp without ruling out infectious causes first 3, 4

Red Flags Requiring Urgent Evaluation

• Eye pain, vision changes, or periorbital lesions - risk of vision loss 1
• Altered mental status or severe headache - possible meningeal involvement 1
• Immunocompromised state - higher risk of dissemination 1
• Fever with rapidly spreading erythema - consider bacterial superinfection or cellulitis 5