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A 26 yr old female with no known infections, diabetes or hypertension, had compliants of small white patches (hypopignented)6-8 behind the neck

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Clinical Analysis: Multiple Small Hypopigmented Patches on the Neck in a 26-Year-Old Female

Most Likely Diagnosis: Pityriasis (Tinea) Versicolor

Given the patient's age (26), sex (female), no known systemic disease, and 6-8 small white (hypopigmented) patches behind the neck, pityriasis versicolor is the leading diagnosis. It is a superficial fungal infection caused by Malassezia spp. (previously Pityrosporum) - a lipophilic yeast that is part of normal cutaneous flora but becomes pathogenic under certain conditions (heat, humidity, oily skin, sweat).
Scaly hypopigmented macules of tinea versicolor on the chest and neck
Fitzpatrick's Dermatology - Fig. 76-14: Scaly, hypopigmented macules of tinea versicolor on chest/neck region
Key clinical features supporting this:
  • Small, well-demarcated macules/patches with fine, bran-like scale
  • Neck, back, chest, upper arms ("cape-like" distribution) are classic locations
  • The yeast produces azelaic acid which inhibits melanin synthesis → hypopigmentation
  • Patches may appear lighter or darker depending on skin tone and season
  • Typically asymptomatic or mildly pruritic
  • Yellow-green fluorescence under Wood's lamp
  • KOH microscopy shows the classic "spaghetti and meatballs" pattern (short hyphae + round spores)
(Textbook of Family Medicine 9e, p. 942)

Differential Diagnoses to Consider

ConditionDistinguishing Features
Pityriasis versicolorFine scale, sebaceous distribution, Wood lamp fluorescence (yellow-green), KOH positive
VitiligoComplete depigmentation (chalk-white), symmetric, enhances brightly on Wood lamp, NO scale
Leprosy (tuberculoid/borderline)Hypopigmented with reduced/absent sensation (anesthesia) in the patch, thickened nerves; important in endemic areas
Pityriasis albaIll-defined, dry, slightly scaly patches mainly on face; common in children/young adults with atopic tendency
Nevus depigmentosusCongenital or early-childhood onset, stable size, jagged border, NO scale
Post-inflammatory hypopigmentationHistory of prior skin inflammation/injury at the site
Nevus anemicusWhite macule that disappears on diascopy (blanching), present since birth
(Fitzpatrick's Dermatology, pp. 1367-1368)

Important Clinical Clues to Help Narrow Down

  1. Check for sensation in the patches - if reduced, leprosy must be excluded (this is especially relevant in South Asian/tropical populations).
  2. Wood's lamp exam:
    • Tinea versicolor → yellow-green/coppery fluorescence
    • Vitiligo → brilliant white/chalk enhancement
    • No enhancement → postinflammatory, pityriasis alba
  3. Fine scale on stretching (scraping sign) - positive in tinea versicolor
  4. KOH scraping - confirms tinea versicolor with spaghetti-and-meatballs pattern
Hypopigmented patches of leprosy on upper arm
Fig. 76-15 (Fitzpatrick's): Hypopigmented patches of leprosy - note they look similar but have sensory loss

Management (if Tinea Versicolor confirmed)

Topical (first-line):
  • Selenium sulfide 2.5% lotion/shampoo - apply daily for 10 minutes for 7 days (SOR: B)
  • Ketoconazole 2% shampoo - apply for 3 days (SOR: B)
  • Topical azoles (clotrimazole, miconazole) - applied twice daily for 2-4 weeks
Systemic (for extensive/recurrent disease):
  • Oral fluconazole 400 mg single dose - best clinical and mycologic cure rate, no relapse at 12 months (SOR: B)
  • Oral itraconazole 200 mg BD × 1 day/month - effective prophylaxis for recurrence (SOR: B)
Counseling points:
  • Skin color may take weeks to months to normalize even after cure - this is NOT treatment failure
  • Tends to recur, especially in warm/humid weather
  • Antidandruff shampoos (containing selenium sulfide or zinc pyrithione) can help prevent recurrence
(Textbook of Family Medicine 9e, pp. 942-943)

Summary

The most probable diagnosis is pityriasis versicolor - a benign, superficial Malassezia infection presenting as multiple small hypopigmented patches in a young adult. A Wood's lamp exam and/or KOH scraping can confirm this quickly at the bedside. Leprosy must be actively excluded (especially in endemic regions) by testing for sensory loss in the patches. Vitiligo is less likely given the small size, neck-only distribution, and absence of complete depigmentation.
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