#84: Hypopigmented & Depigmented Skin Lesions: An En-LIGHT-ening Review

May 10, 2023 | By Sam Masur

Audio

Summary:

Trying to hone your on-the-spot derm diagnoses? White knuckling your way through patient questions about random skin findings? Get ready, because pediatric dermatology expert Dr. Craig Rohan is back to shed some light on the diagnosis and management of hypo- and depigmented lesions in pediatric care!

Hypopigmentation/Depigmentation Pearls

1. Post-inflammatory hypopigmentation is a common response to skin trauma in patients with Fitzpatrick Type 3 skin or lighter. Pityriasis alba is essentially a post-inflammatory response to eczema. 
2. Treatment is rarely needed in pityriasis alba, but topical steroids and calcineurin inhibitors can be helpful.
3. Vitiligo is often associated with autoimmune conditions. Dr. Rohan advises providers to obtain a CBC and TSH at time of diagnosis and ask about family history of autoimmune issues. 
4. There are effective treatments available for vitiligo. In primary care it is reasonable to start with alternating topical steroids and calcineurin inhibitors while also managing any identified underlying autoimmune disorders.
5. Important differential diagnoses to consider for hypopigmentation and depigmentation include congenital conditions (e.g., tuberous sclerosis, oculocutaneous albinism), infectious diseases (e.g., Hansen disease), vitamin deficiencies, and malignancy (e.g., cutaneous lymphoma).

Hypopigmented & Depigmented Skin Lesion Notes 

Hypopigmentation Case: Pityriasis Alba

Pathophysiology

• Occurs as a result of a brief eczematous eruption where melanocytes are damaged disproportionately to the rest of the skin. There is usually a mild short-lived preceding eczematous scale.
• Included in the minor diagnostic criteria for atopic dermatitis.
• May be more visible in summer months when there is greater contrast between unaffected skin and post-inflammatory hypopigmentation.

Presentation

• 5-25 mm (dime to half-dollar size) hypopigmented, relatively circular patches or macules.
• Photodistributed, most common on face.
• May also have other signs of atopic dermatitis (e.g., lichenified eczema on antecubital fossa, hyperlinear palms, ichthyosis).

Diagnosis

• Visual diagnosis—pattern recognition is key!

Management

• Usually none is needed—emphasize sunscreen!
• If other signs of atopic dermatitis are present, emphasize emollients and consider topical steroids or steroid-sparing agents (see our episode on atopic dermatitis for more info!). 
• If more extensive can use narrow-band UV phototherapy.
• Timing of resolution is usually 3-8 weeks, but depends on time of year (will take longer with increased sun exposure).

Differential Diagnoses for Hypopigmented Lesions

• Post-inflammatory hypopigmentation/hypomelanosis (note: pityriasis alba could technically fall into this bucket): Common response to skin trauma in patients with Fitzpatrick Type 3 skin or lighter (darker skin usually will have a hyperpigmented response). Might occur after a cut, popping a zit, or applying liquid nitrogen. Will slowly “fill back in with melanin” over time. 
• Tinea/pityriasis versicolor: See our episode on tinea infections! Yeast infection caused by Malassezia species, which has an endogenous pigmentation enzyme that bleaches melanin. Tends to be very symmetric. Can be lighter or darker.
• Nevus anemicus/nevus depigmentosus: A less-common type of birthmark that starts hypopigmented but can become depigmented over time. 
• Hypomelanosis of ito: Rare congenital condition that typically presents in younger kids (infants 4+ months and toddlers). Lesions follow embryonic cleavage planes and have reticulated, jagged edges (see image below). Associated with increased risk for developmental delay, seizure, and glaucoma.
• Tuberous sclerosis: Congenital condition that presents with hypopigmented ash-leaf macules with a reticulated, jagged edge (see image below). Often subtle—may only be identified on Wood’s lamp evaluation of a child with developmental delay. 
• Hansen disease (leprosy): Infectious disease caused by mycobacteria. Typically will have a long incubation period from time of exposure. Initial skin lesions are usually hypopigmented patches that then evolve to more distinct lesions that differ depending on subtype (tuberculoid vs lepromatous) (see image)
• Vitamin deficiencies: Consider Vitamin B12, copper, and iron deficiency (Madireddy & Crane, 2022).
• Cutaneous lymphoma: Varying presentations, including hypopigmented patches or plaques (Wohlmuth-Wieser, 2021). Can be a unifying diagnosis to consider when a patient presents with multiple different lesion types.

Depigmentation Case: Vitiligo

Pathophysiology

• Multifactorial disorder characterized by the loss of functioning melanocytes (Bergqvist &· Ezzedine, 2020).
• Associated with several autoimmune conditions including endocrine disorders (particularly Hashimotos’ thyroiditis), rheumatoid arthritis, pernicious anemia, alopecia areata, and lupus (Bergqvist &· Ezzedine, 2020). Ask about family history!
• Can be triggered by onset/poor control of autoimmune disease, or reactive to another inflammatory process (e.g., new onset melanoma). A full skin exam is appropriate at time of diagnosis. 

Presentation

• Sharply depigmented lesions.
• Typically presents in adolescence-early 20s, rarely before age 3.
• Often will see Koebner’s phenomenon (lesion onset following mechanical trauma) (Bergqvist &· Ezzedine, 2020).
• Various phenotypes – note that may occur only in the genital region which can lead to missed or late diagnosis.

Diagnosis

• Typically a clinical/visual diagnosis.
• Dr. Rohan will typically obtain a CBC and TSH at time of diagnosis to screen for common associated autoimmune disorders. Additional testing (e.g., fasting glucose) may be appropriate per presentation and family history. Note that guidelines from Choosing Wisely advise against routine lab testing in the absence of signs, symptoms, or family history. 

Management

• In primary care, can start with topical corticosteroids. One approach Dr. Rohan uses is to have patients apply the topical steroid Mondays through Fridays and then on weekends use topical calcineurin inhibitor BID. As the patient starts to improve, flip and use the topical calcineurin inhibitor Monday through Friday with the steroid on the weekends (can also do this from the start for areas where skin is more fragile).
• Manage underlying endocrine disorder(s). 
• Narrow band ultraviolet light therapy is an effective treatment with fewer side effects than topical steroids. Usually is repeated 2-3 times per week and takes 5-10 minutes per treatment. 
• Systemic JAK stat inhibitors have good efficacy data and are  approved for use in adults with vitiligo (Qi et al., 2021). Dr. Rohan advises that there is some basis for off-label use in children (they have been used off-label in children for >10 years for alopecia areata). Topical JAK stat inhibitors are approved for use in children. The main issue for these medications is insurance coverage/cost.
• Cyclosporines are an off-label treatment option, but are complicated by the need to monitor labs during use. 
• As vitiligo improves, will initially see depigmented circle that scallops around the edges with “polka dots” of pigments in the center from pluripotent cells repopulating skin with melanocytes (see image below).

Differential Diagnoses for Depigmentation Lesions

• Cutaneous lymphoma (see above).
• Waardenburg syndrome: Genetic condition that causes inability to produce melanosomes, frequently also associated with hearing loss. 
• Piebaldism: Condition in which melanoblasts are unable to migrate to the correct location.
• Oculocutaneous albinism: Occurs as a result of genetic conditions that block the production or transportation of melanin. Patients are at increased risk for sunburns, vision issues, and skin cancers, including at a young age. Appropriate to refer for a full workup to evaluate for associated disorders (e.g., Chediak-Higashi syndrome).

Goal

Listeners will explain the diagnosis, management, and differential diagnosis of common hypopigmented skin lesions in a pediatric population.

Learning objectives

After listening to this episode listeners will…  

1. Diagnose common skin conditions causing hypopigmentation and depigmentation.
2. Recognize less common conditions that can cause hypopigmentation and depigmentation and refer for further evaluation where appropriate. 
3. Discuss appropriate treatment options for pityriasis alba and vitiligo.
4. Select appropriate laboratory testing to be ordered at the time of vitiligo diagnosis.

Disclosures

Dr. Rohan reports no relevant financial disclosures. The Cribsiders report no relevant financial disclosures. 

Citation

Engel S, Rohan C, Cruz M,, Masur S, Chiu C, Berk J. “84: Hypopigmented & Depigmented Skin Lesions: An En-Light-ening Review”. The Cribsiders Pediatric Podcast. https:/www.thecribsiders.com/ May 10, 2023.