Model Answer
0 min readIntroduction
Dermatological conditions often present with overlapping symptoms, necessitating a careful clinical evaluation. Pruritic, scaly lesions, particularly those exhibiting hyperpigmentation and photosensitivity, can indicate a range of disorders. The distribution of lesions – affecting skin creases, eyelids, and the face – narrows the differential diagnosis considerably. Given the patient’s age and the described clinical features, a strong consideration must be given to conditions affecting melanin production and skin barrier function. This presentation strongly suggests a diagnosis of pityriasis alba, although other possibilities need to be considered.
Likely Diagnosis: Pityriasis Alba
Based on the clinical presentation, the most likely diagnosis is Pityriasis Alba. This is a common, mild form of eczema that primarily affects children and young adults, but can persist or appear in individuals up to 45 years of age. It is characterized by hypopigmented (though can appear hyperpigmented in darker skin types), scaly, slightly raised patches, often on the face, neck, upper arms, and legs. The involvement of skin creases, eyelids, post-auricular area, and nasolabial folds is highly suggestive.
Key Clinical Features Supporting the Diagnosis:
- Itchy, scaly lesions: A hallmark of eczema, including pityriasis alba.
- Hyperpigmented lesions (in darker skin): While classically hypopigmented, lesions can appear hyperpigmented, especially after inflammation subsides, in individuals with darker skin tones.
- Distribution: Involvement of the face, neck, upper and lower limbs, and specifically skin creases, eyelids, post-auricular area, and nasolabial folds is typical.
- Photosensitivity: Although not a primary feature, individuals with pityriasis alba may experience worsening of symptoms with sun exposure.
- Age: While more common in children, it can occur in adults.
Differential Diagnosis
While pityriasis alba is the most likely diagnosis, other conditions should be considered:
- Atopic Dermatitis: Can present with similar itchy, scaly lesions, but typically has a more widespread distribution and a stronger personal or family history of atopy (asthma, allergic rhinitis).
- Seborrheic Dermatitis: Often affects areas rich in sebaceous glands (scalp, face, chest), causing greasy, scaly lesions. Less likely given the distribution described.
- Tinea Corporis (Ringworm): A fungal infection that presents with annular, scaly lesions. Usually more sharply demarcated and often responds to antifungal treatment.
- Vitiligo: Causes well-defined, completely depigmented patches. Pityriasis alba typically has some degree of pigmentation, even if reduced.
- Post-inflammatory Hyperpigmentation: Can occur after any inflammatory skin condition, but the underlying cause needs to be identified.
Investigations
Diagnosis is usually clinical. However, investigations can help rule out other conditions:
- Skin Scraping for KOH Examination: To rule out fungal infection (Tinea).
- Skin Biopsy: Rarely needed, but can be considered if the diagnosis is uncertain. Histopathology shows mild spongiosis and perivascular lymphocytic infiltrate.
- Patch Testing: To identify potential allergens if atopic dermatitis is suspected.
Management
Management focuses on symptom relief and preventing flares:
- Emollients: Regular use of moisturizers to hydrate the skin and restore the skin barrier.
- Topical Corticosteroids: Low-potency corticosteroids can be used for short periods to reduce inflammation and itching.
- Sun Protection: Avoidance of sun exposure and use of sunscreen.
- Topical Calcineurin Inhibitors: Tacrolimus or pimecrolimus can be used as steroid-sparing agents.
Conclusion
In conclusion, based on the presented clinical features – recurrent itchy, scaly, hyperpigmented lesions with a characteristic distribution and photosensitivity – pityriasis alba is the most probable diagnosis. While a differential diagnosis should be considered, investigations are often unnecessary. Management focuses on supportive care with emollients, topical corticosteroids, and sun protection. Long-term prognosis is generally good, with symptoms often resolving spontaneously over time.
Answer Length
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