Pityriasis Alba



Figure 17.1
Ill-defined, hypopigmented slightly scaly patches on the right cheek





Clinical Differential Diagnosis


The findings were thought to be most consistent with pityriasis alba. The differential diagnosis for pityriasis alba includes tinea versicolor, nevus depigmentosus, vitiligo, nummular dermatitis, hypopigmented mycosis fungoides, tuberous sclerosis, and leprosy (Table 17.1).


Table 17.1
Differential diagnosis















































Diagnosis

Distinguishing features

Tinea versicolor

More extensive with more evident scale

Common location: on trunk

Nevus depigmentosus

Usually a persistent, solitary, and hypopigmented patch with scalloped borders

Present at birth or before age 3

Common location: on trunk

Vitiligo

Completely depigmented and very well demarcated macules/patches

Accentuated by Wood’s lamp

Nummular dermatitis

Usually more well-defined, raised plaques with more prominent scale

Associated with intense pruritus

Hypopigmented mycosis fungoides

Rare condition

Common location: on trunk

Tuberous sclerosis

Present at or around birth

Associated with other systemic manifestations

Common location: on trunk

Leprosy

May have associated anesthesia/hypoesthesia with nerve involvement on histology


Histopathology


A biopsy was not performed in this case because the physical examination was felt to be diagnostic. Pityriasis alba (PA) is typically nonspecific on histopathology, with early lesions demonstrating spongiosis, follicular plugging, focal parakeratosis and acanthosis, atrophic sebaceous glands, superficial perivascular lymphocytic infiltrate, and dermal edema. Late lesions show nonspecific changes of hyperkeratosis, focal parakeratosis, and spongiosis. There is a variable reduction of melanin in the basal layer but no significant difference in melanocyte count (In et al. 2009).


Diagnosis


Pityriasis Alba


Case Treatment


The nature and course of this condition was discussed with the patient as well as treatment options, including monitoring and topical therapies. Hydrocortisone 1 % cream daily 1 week on, 1 week off as needed for pruritus was prescribed. In addition, the importance of dry skin care, including frequent emollient use, and sun protection was emphasized.


Discussion


Pityriasis alba (PA) is a common skin disorder in all skin types and ethnicities (In et al. 2009). It is characterized by asymptomatic or mildly pruritic hypopigmented ill-defined irregular patches covered with fine scale located primarily on the face but can also involve the trunk and limbs when diffusely involved. Epidemiologic studies have demonstrated that PA is the most common hypopigmentary disorder in children. It most frequently affects children 3–16 years of age but may occur in adulthood as well (In et al. 2009). It has a higher prevalence in individuals with darker skin (FST III-VI), with one study demonstrating 98.1 % of PA patients within these skin types (Blessmann Weber et al. 2002). This may be because the lesions are more apparent in darker skin types who tan more easily except in the areas with PA lesions (Blessmann Weber et al. 2002). In addition, lesions may be more cosmetically bothersome to patients with darker complexions, making them more likely to seek treatment.

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Oct 6, 2016 | Posted by in Dermatology | Comments Off on Pityriasis Alba
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