What is the differential diagnosis and treatment for a spot under the eye in a 13-year-old?

Differential Diagnosis and Treatment for a Spot Under the Eye in a 13-Year-Old

Begin with preservative-free ocular lubricants (hyaluronate or hydroxypropyl-guar drops) applied 2-4 times daily as first-line therapy while simultaneously evaluating for features requiring urgent ophthalmology referral. 1

Differential Diagnosis

The differential diagnosis for a "spot under the eye" in a 13-year-old includes:

Dermatologic/Pigmentary Causes

• Dermal melanocytosis (including periorbital melanosis): Bilateral homogeneous pigmented macules in the suborbital region, histologically confirmed as dermal melanocytosis, which represents the most common cause of "dark rings under the eyes" in Asian populations 2
• Vascular circles: Related to visible periorbital vasculature 3
• Structural shadows: From anatomical features like tear trough deformity 3
• Pigment shadows: From post-inflammatory hyperpigmentation or other causes 3

Inflammatory/Infectious Causes

• Periorbital dermatitis: Including atopic dermatitis-related changes, which can present with redness, irritation, and discharge 4, 1
• Dupilumab-related ocular surface disorders (DROSD): If the patient is on dupilumab therapy for atopic dermatitis, presenting with conjunctival injection and discharge 4
• Allergic conjunctivitis: With follicular reaction and associated symptoms 4
• Viral conjunctivitis: Including HSV or molluscum contagiosum with periocular lesions 4
• Bacterial conjunctivitis: With purulent discharge 4

Structural/Anatomical Causes

• Preauricular pit infection: If the "spot" is actually near the preauricular area, requiring fluoroquinolone therapy 5
• Eyelid edema/fatty bags: From various causes including allergic reactions 3
• Chalazion or hordeolum: Localized eyelid lesions 4

Neoplastic Causes (Less Common)

• Ocular surface squamous neoplasia: Papillomatous or sessile nodules with conjunctival hyperemia 4
• Melanoma: Pigmented or non-pigmented lesions 4
• Sebaceous gland carcinoma: Hard nodular mass with yellowish discoloration 4

Red Flags Requiring Emergency Ophthalmology Referral (Within 24 Hours)

Use the RAPID acronym to identify features requiring urgent assessment: 1

• Redness (severe conjunctival injection)
• Acuity loss (visual impairment)
• Pain (moderate-to-severe)
• Intolerance to light (photophobia)
• Damage to cornea (corneal involvement)

Additional urgent referral criteria for adolescents (7-17 years): 4, 1

• Severe purulent discharge
• History of herpes simplex virus eye disease
• Corneal infiltrate or ulcer
• Suspected neoplastic lesion

Treatment Algorithm

Step 1: Initial Assessment and First-Line Treatment

For mild periorbital dermatitis/irritation (most common presentation):

• Start preservative-free ocular lubricants containing hyaluronate or hydroxypropyl-guar, applied 2-4 times daily (65% response rate) 4, 1
• Assess for red flag features requiring urgent referral 1

Step 2: Escalation for Moderate Cases (If No Response at 2-4 Weeks)

Add topical antihistamine therapy:

• Olopatadine eye drops twice daily in addition to lubricants (42% response rate) 4, 1
• Alternative antihistamines for ages >12 years: Antazoline with xylometazoline 2-3 times daily for 7 days 4
• Mast cell stabilizers: Sodium cromoglycate 4 times daily (all ages) or Lodoxamide 4 times daily (>4 years) 4

Step 3: Severe or Refractory Cases

For moderate-to-severe cases not responding to lubricants and antihistamines:

• Tacrolimus 0.1% ointment once daily to external eyelids and lid margins (89% response rate, most effective topical treatment) 1
• Important caveat: For 7-17 year-olds, seek ophthalmology advice before initiating tacrolimus 4
• Refer to ophthalmology for assessment within 4 weeks when using tacrolimus 4

Step 4: Referral Pathways

Standard/routine ophthalmology referral (within 4 weeks):

• Mild-to-moderate cases not responding to topical lubrication or antihistamine eyedrops 4
• Any patient on tacrolimus therapy 4

Urgent ophthalmology referral (within 24 hours to 4 weeks based on clinical judgment):

• Severe cases with red flag features 4, 1
• Progressive symptoms despite appropriate therapy 1

Special Considerations for Specific Diagnoses

If dermal melanocytosis is confirmed:

• Q-switched ruby laser therapy can achieve good-to-excellent clearance (>40-70% improvement) in patients with bilateral homogeneous pigmented macules 2
• Requires histological confirmation with Masson-Fontana silver stain and S100 staining 2

If preauricular pit infection is suspected:

• First-line therapy: Fluoroquinolones (ciprofloxacin or levofloxacin) for coverage of Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pyogenes 5
• Alternative regimens: Clindamycin, ceftazidime, or cefepime based on severity and local resistance patterns 5

Common Pitfalls to Avoid

• Do not delay ophthalmology referral beyond 4 weeks if symptoms persist despite appropriate first-line therapy 1
• Monitor for complications including skin atrophy, glaucoma, and cataracts if corticosteroids are used (though not first-line in this age group) 1
• Do not use preserved lubricants, as preservatives can worsen inflammation 4
• Do not assume all "spots under the eye" are benign pigmentation—always assess for infectious, inflammatory, and neoplastic causes 4
• In adolescents with severe or atypical presentations, maintain high suspicion for neoplastic processes requiring biopsy 4

Follow-Up

• Review at 2-4 weeks to assess treatment response and escalate therapy if no improvement or worsening symptoms 1
• Continue monitoring for treatment response and adjust therapy according to the treatment ladder 4, 1