Disorders of Hypopigmentation in Children

Hypopigmentation or “loss of normal skin color” is commonly encountered in pediatric dermatology outpatient department. These can be due to various causes, classified in Table 1.Table 1: Classification of disorders of hypopigmentation Primary disorders of pigmentation targeting melanocytes or melanogenesis, further classified as congenital or acquired Secondary loss of pigment due to other dermatosis. It is important to differentiate these conditions as management, disease course, and prognosis are different. While there is no definitive treatment available for genetic diseases, yet, photoprotection and genetic counseling in albinism and management of associated systemic abnormalities remain paramount in various syndromes and hypomelanosis of Ito. For localized diseases such as nevus depigmentosus and piebaldism, excision, skin grafting, and cosmetic camouflage remain effective therapeutic options. Secondary disorders cause significant distress in parents who often confuse it with vitiligo, a stigmatized disease with profound psychosocial impact. There are many immunosuppressive and repigmenting agents available for vitiligo often requiring long-term follow-up. Treatment of infection, withdrawal of inciting agent, and treatment of inflammatory pathology suffice in secondary or postinflammatory hypopigmentary disorders. Melanoblasts are neural crest-derived precursors of melanocytes, which migrate to epidermis and hair follicles. The skin consists of a structural and functional organization of keratinocytes and melanocytes, known as “epidermal melanin units.” Melanin synthesis occurs inside membrane-bound organelles “melanosomes” of melanocytes, which are subsequently transported and transferred to keratinocytes through dendrites. Disorders of hypopigmentation may result from defects in melanoblast proliferation and migration, melanin synthesis, melanosome transfer, or destruction of melanocytes.Image 1: Generalized loss of pigment of the skin, hair, and eyes present since birth in a case of oculocutaneous albinismImage 2: Hypopigmented streaks along lines of Blaschko (unilateral in this case but can be bilateral) present since birth in hypomelanosis of Ito. Neurological, ophthalmological, and skeletal abnormalities may be associatedImage 3: Localized hypopigmented lesion of nevus depigmentosus with serrated borders (“splashed paint appearance”) which does not cross midline. It may not be apparent at birth and may be noticed few weeks to years laterImage 4: Sharply demarcated milky-white patches of vitiligo. It is usually acquired, progressive and may have segmental or nonsegmental distribution (focal/acrofacial/generalized). Leukotrichia or “white hair” can also be found. Lesions may not be that well-defined when disease is unstable. Hypopigmented borders, confetti-like lesions at periphery, and Koebner phenomenon (lesions occurring at sites of trauma) are some of the signs of active diseaseImage 5: Hypopigmented, scaly lesions (which get more prominent on scratching-coup d’ongle/scratch sign) of pityriasis versicolor. Trunk is usually affected and may be associated with itchingImage 6: Multiple hypopigmented, anesthetic, and infiltrated plaques of leprosy. Lesions may be single or multiple and flat or raised, but lesional loss of sensation is characteristic. Presence of nerve enlargement, endemicity, presence of pseudopodia or satellite lesions/inverted saucer-shaped morphology, and evidence of lepra reaction further help in clenching diagnosisImage 7: Ill-defined slightly erythematous lesions of pityriasis alba showing fine scaling. Erythema usually subsides and is followed by persistent hypopigmentation and mild scalingImage 8: Hypopigmentation seen in a case of seborrheic dermatitis. There is involvement of seborrheic sites apart from the scalp (nasolabial folds, ear creases, eyelids, eyebrows, glabella, presternal area, upper back), and lesions may range from fine flaking to thick and yellow-crusted erythematous lesionsImage 9: Postburn depigmentation in center with hyperpigmentation at borders. Usually history of burn, trauma, or exposure to chemicals is elicited in these casesImage 10: Ash-leaf-shaped hypopigmented lesion seen in a patient of tuberous sclerosis. Presence of multiple lesions, characteristic lance-ovate shape, and other cutaneous and extracutaneous features of tuberous sclerosis help to differentiate from nevus depigmentosusImage 11: (a) Poststeroid depigmentation seen in a case of tinea cruris due to inadvertent over-the-counter abuse of topical steroids. Primary dermatosis may not be evident in all cases but careful history taking including the use of medications used along with other features of steroid abuse such as atrophy, telangiectasia, and hypertrichosis may help. (b) Postintramuscular steroid lipoatrophy and depigmentation. Again, a history of intramuscular injections and temporal correlation helps in identifying the diagnosisDeclaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.