History

Fact Explanation
Skin patch Pityriasis alba is a common skin condition of unknown etiology. It is characterized by round or oval shaped patches of the skin appear on the face, upper arms, neck, and shoulders. The commonest site is the cheeks. The appearance of the patch can be variable. Some are raised while some are flat. The surface is either red or pale. They may present as multiple lesions. The lesions in the trunk are larger than the lesions elsewhere. The lesions are usually neither itchy nor painful. Rarely they may be itching. In a rare variant, the lesion is widespread and affects symmetrically, involving a large portion of the skin. [1,2,3]
Scaling Some lesions are scaly. The lesion usually heals with no abnormality left behind. [1,2,3]
At risk population Pityriasis alba is most often seen in children between the ages of 3 and 16 years. It is more common in males than females and occurs more frequently in lighter-skinned patients. [1,2,4]
References
  1. VINOD S, SINGH G, DASH K, GROVER S. Clinico epidemiological study of pityriasis alba. Indian J Dermatol Venereol Leprol [online] 2002 Nov-Dec, 68(6):338-40 [viewed 19 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/17656993
  2. CARNEIRO FR, AMARAL GB, MENDES MD, QUARESMA JA. Tissue immunostaining for factor XIIIa in dermal dendrocytes of pityriasis alba skin lesions. An Bras Dermatol [online] 2014 Mar-Apr, 89(2):245-8 [viewed 19 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/24770500
  3. SORI T, NATH AK, THAPPA DM, JAISANKAR TJ. Hypopigmentary disorders in children in South India. Indian J Dermatol [online] 2011 Sep-Oct, 56(5):546-9 [viewed 19 August 2014] Available from: doi:10.4103/0019-5154.87152
  4. PLENSDORF S, MARTINEZ J. Common pigmentation disorders. Am Fam Physician [online] 2009 Jan 15, 79(2):109-16 [viewed 19 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/19178061

Examination

Fact Explanation
Skin patch Patient may present with several ill defined raised or flat skin patches of lesions which are round or oval in shapes. They occur more commonly on face, upper arms, shoulders and neck. The size is 0.5–2 cm, although may be larger if they occur on the body (up to 4 cm). Trunk is less commonly involved. The surface can be pale (hypopigmented), erythematous or normal. Sometimes scales can be seen. [1,2,3]
References
  1. VINOD S, SINGH G, DASH K, GROVER S. Clinico epidemiological study of pityriasis alba. Indian J Dermatol Venereol Leprol [online] 2002 Nov-Dec, 68(6):338-40 [viewed 19 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/17656993
  2. CARNEIRO FR, AMARAL GB, MENDES MD, QUARESMA JA. Tissue immunostaining for factor XIIIa in dermal dendrocytes of pityriasis alba skin lesions. An Bras Dermatol [online] 2014 Mar-Apr, 89(2):245-8 [viewed 19 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/24770500
  3. SORI T, NATH AK, THAPPA DM, JAISANKAR TJ. Hypopigmentary disorders in children in South India. Indian J Dermatol [online] 2011 Sep-Oct, 56(5):546-9 [viewed 19 August 2014] Available from: doi:10.4103/0019-5154.87152

Differential Diagnoses

Fact Explanation
Vitiligo Vitiligo is an acquired, progressive disorder, in contrast to nevus depigmentosus, which is a stable congenital leukoderma. The face is a common site for vitiligo, but the distribution is most commonly around the eyes or mouth, and, in contrast to pityriasis alba, the pigment loss is complete. [1]
Tinea corporis Tinea corporis (ringworm) is the name used for infection of the trunk, legs or arms with a dermatophyte fungus. Tinea corporis may be acute (sudden onset and rapid spread) or chronic (slow extension of a mild, barely inflamed, rash). It usually affects exposed areas but may also spread from other infected sites. [2]
Nummular eczema Discoid eczema or nummular dermatitis is a recurrent or chronic form of eczema that can affect at any age though it is more common in 6th decade of life and affects males and females equally. The exact cause is still unknown and is thought to be strongly associated with skin dryness. The disease is characterized by distinct, coin-shaped (nummular) or oval blistered or dry skin lesions. Nummular dermatitis often starts off after minor skin injuries. Patient may have a days-to-months' history of rash. Lesions starts as small raised bumps (papules) or small fluid-filled blisters less than 1cm in diameter (vesicles). Then they unit in to form palpable flat lesion usually greater than 1 cm diameter. (plaques). One or many plaques appear, and may persist for weeks or months. The plaques are pink, red, or brown and well defined. Rashes can affect any part of the body, but the legs and buttocks are the most common areas. They usually occur symmetrically. [3]
References
  1. LADDHA NC, DWIVEDI M, MANSURI MS, GANI AR, ANSARULLAH M, RAMACHANDRAN AV, DALAI S, BEGUM R. Vitiligo: interplay between oxidative stress and immune system. Exp Dermatol [online] 2013 Apr, 22(4):245-50 [viewed 19 August 2014] Available from: doi:10.1111/exd.12103
  2. BACHMEYER C, BUOT G. Tinea corporis in a mixed martial arts fighter. CMAJ [online] 2013 Jul 9, 185(10):897 [viewed 28 July 2014] Available from: doi:10.1503/cmaj.120813
  3. IAMTON S, TANGJATURONRUSAMEE C, KULTHANAN K. Clinical features and aggravating factors in nummular eczema in Thais. Asian Pac J Allergy Immunol [online] 2013 Mar, 31(1):36-42 [viewed 28 July 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/23517392

Investigations - for Diagnosis

Fact Explanation
Wood's light examination Wood's light is an ultraviolet light used to accentuate pigmentary changes in skin. It helps in determining whether a patient’s rash is due to vitiligo, which will glow more brightly and have edges with sharper demarcation. [1,2,3,4]
Microscopic examination Skin scraping are taken and prepared with potassium hydroxide preparation for microscopical examination. This is mostly to exclude fungal diseases when nummular dermatitis can not be differentiated from tinea/ ringworm infections. [1,2,3]
Biopsy Biopsy is performed in rare instances where the patient presents with atypical lesions. Findings such as irregular or markedly reduction in pigment by melanin of the basal layer with without a significant contrast in melanocyte count between normal and lesional skin and reduced active melanocytes aid in diagnosis. But non of these are pathognomonic. [1,2,3,4]
References
  1. CARNEIRO FR, AMARAL GB, MENDES MD, QUARESMA JA. Tissue immunostaining for factor XIIIa in dermal dendrocytes of pityriasis alba skin lesions. An Bras Dermatol [online] 2014 Mar-Apr, 89(2):245-8 [viewed 19 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/24770500
  2. SORI T, NATH AK, THAPPA DM, JAISANKAR TJ. Hypopigmentary disorders in children in South India. Indian J Dermatol [online] 2011 Sep-Oct, 56(5):546-9 [viewed 19 August 2014] Available from: doi:10.4103/0019-5154.87152
  3. VINOD S, SINGH G, DASH K, GROVER S. Clinico epidemiological study of pityriasis alba. Indian J Dermatol Venereol Leprol [online] 2002 Nov-Dec, 68(6):338-40 [viewed 19 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/17656993
  4. PLENSDORF S, MARTINEZ J. Common pigmentation disorders. Am Fam Physician [online] 2009 Jan 15, 79(2):109-16 [viewed 19 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/19178061

Management - Specific Treatments

Fact Explanation
Moisturizing creams No treatment is necessary, but a moisturizing cream may improve the dry appearance. [1,2]
Topical steroids Weak topical steroids such as 1% hydrocortisone are recommended in case of pruritus or erythema at the initial stage. [1,2]
Pimecrolimus Pimecrolimus is a topical steroid-free medication with immune-modulating and anti-inflammatory properties. 1% Pimecrolimus is recommended for some patients. It is a cheaper alternate for 0.1% Tacrolimus oinment. [1,2,3]
Laser therapy Laser treatment twice a week for 12 weeks has been effective in some patients. [1,2,4]
PUVA therapy Psoralen plus ultraviolet light A (PUVA) photochemotherapy is rarely implicated in extensive cases. [2,3,4]
References
  1. VINOD S, SINGH G, DASH K, GROVER S. Clinico epidemiological study of pityriasis alba. Indian J Dermatol Venereol Leprol [online] 2002 Nov-Dec, 68(6):338-40 [viewed 19 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/17656993
  2. SORI T, NATH AK, THAPPA DM, JAISANKAR TJ. Hypopigmentary disorders in children in South India. Indian J Dermatol [online] 2011 Sep-Oct, 56(5):546-9 [viewed 19 August 2014] Available from: doi:10.4103/0019-5154.87152
  3. CARNEIRO FR, AMARAL GB, MENDES MD, QUARESMA JA. Tissue immunostaining for factor XIIIa in dermal dendrocytes of pityriasis alba skin lesions. An Bras Dermatol [online] 2014 Mar-Apr, 89(2):245-8 [viewed 19 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/24770500
  4. PLENSDORF S, MARTINEZ J. Common pigmentation disorders. Am Fam Physician [online] 2009 Jan 15, 79(2):109-16 [viewed 19 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/19178061