• Autosomal dominant.

• Mutation in the ATP2A2 gene causing dysfunction of SERCA2 protein, interfering with cellular calcium signaling.

• Clinical features.

– Onset usually between ages 6 and 20 years, with peak during adolescence.

– Chronic course, often worse in summer.

– Crusted, pink-red to brown papules that may coalesce into plaques (Fig. 48.1) in a ‘seborrheic’ and sometimes intertriginous distribution (Fig. 48.2).

– Hypopigmented macules may be the predominant feature, especially in darker skin types (Fig. 48.3).

– Itching and malodor can be prominent.

– Flat-topped skin-colored to brown papules (resemble flat warts) on the dorsal hands and feet (Fig. 48.4).

– Palmoplantar keratotic papules (Fig. 48.5).

– Nail changes, e.g. distal notching with longitudinal erythronychia (see Chapter 58).

– Whitish papules of the oral mucosa (Fig. 48.6).

• Rare subtypes – acral hemorrhagic, segmental (see Chapter 51).

• Exacerbating factors include sunlight, heat, occlusion, sweat, bacterial colonization.

• There may be an association with neuropsychiatric disease (e.g. major depression).

• Complications include bacterial (e.g. Staphylococcus aureus), fungal (e.g. tinea corporis), viral (e.g. herpes simplex virus [HSV]) infections; consider Kaposi’s varicelliform eruption due to HSV in a patient with sudden onset of uniform hemorrhagic crusts, fever, and malaise (Fig. 48.7).

• Histologic features – acantholytic dyskeratosis above suprabasilar clefting.

• DDx: mild forms – severe seborrheic dermatitis, Grover’s disease; predominantly intertriginous – Hailey–Hailey disease, pemphigus vegetans, blastomycosis-like pyoderma, papular acantholytic dyskeratosis (vulvar); acral lesions – acrokeratosis verruciformis of Hopf (may be an allelic disorder or forme fruste; Fig. 48.8), flat warts, stucco keratosis, Flegel’s disease.

• Rx:

– General measures: lightweight clothing, sunscreen, antimicrobial cleansers, keratolytic emollients.

– For symptomatic disease: topical retinoids ± topical CS (to decrease irritation from the former), oral retinoids (e.g. isotretinoin).

– As-needed basis: topical and oral antibiotics and antifungals, systemic antivirals (e.g. acyclovir) for Kaposi’s varicelliform eruption, destructive modalities (e.g. laser treatment) for refractory lesions.

• Autosomal dominant.

• Mutation in the ATP2C1 gene causing dysfunction of a Golgi-associated protein, interfering with cellular calcium signaling.

• Clinical features.

– Onset in the second or third decade but sometimes delayed into the fourth or fifth decade.

– Variable course with remissions and flares.

– Mainly affects the major body folds (Fig. 48.2), including inframammary in women (Fig. 48.9); sometimes other sites affected (Fig. 48.10).

– Moist, malodorous plaques, with erosions, fissures, and flaccid blisters (Fig. 48.9); circinate plaques with eroded/crusted borders (Fig. 48.10).

• Rare subtype – segmental (see Chapter 51).

• Exacerbating factors include friction, heat, sweat, bacterial colonization, application of adhesive tape; complications the same as for Darier disease (see above).

• Histologic features – acantholysis of the majority of the epidermis.

• DDx: intertrigo, irritant contact dermatitis, cutaneous candidiasis, pemphigus vegetans, Darier disease.

• Rx:

– General measures: lightweight clothing, antimicrobial cleansers.

– For symptomatic disease: intermittent topical/intralesional CS.

– As-needed basis: topical and oral antibiotics and antifungals, destructive modalities (e.g. surgical excision, laser treatment) for refractory lesions.