Dyschromatosis Universalis Hereditaria

Dyschromatosis universalis hereditaria is a rare pigmentary disorder with generalised mottled hyper- and hypopigmented macules, starting in infancy or early childhood.

It is described mainly in Japanese, Chinese and Indian families, and is usually autosomal dominant, though recessive and sporadic cases occur. Variants in ABCB6 and SASH1 have been described.

The pigment pattern is permanent, and general health is usually normal. Short stature, hearing loss, learning difficulty and photosensitivity are described in some cases.

Pathophysiology.

Variants in ABCB6 (a melanosomal transporter) and in SASH1 and other genes disrupt melanocyte function and melanosome distribution, giving a pattern of mixed pigment loss and gain.

• Small hyper- and hypopigmented macules, 2 to 4 mm, over the trunk and limbs, and sometimes face, neck and oral mucosa. Palms and soles are usually spared.
• Pattern slowly extends in childhood and then stabilises. No atrophy, telangiectasia or scaling.
• Occasional associated features: short stature, deafness, ocular findings or neurological problems.

• Clinical diagnosis, with a Wood's lamp to show hypopigmented macules. Family history.
• Skin biopsy shows an increase in basal melanin in hyperpigmented areas and a reduction in melanocytes in the hypopigmented areas.
• Genetic testing (ABCB6, SASH1, ADAR) when available.
• Hearing assessment and growth review if other features are present.

Differential diagnosis.

• Dyschromatosis symmetrica hereditaria (limited to the extremities).
• Xeroderma pigmentosum, poikiloderma and incontinentia pigmenti.
• Vitiligo with freckles, post-inflammatory pigment change and reticulate acropigmentation.

• Reassure and counsel the family on the benign, permanent course.
• No treatment reliably restores colour. Camouflage cosmetics and sun protection (SPF 30 or more) are used. Narrowband ultraviolet B or excimer laser for hypopigmented areas has been reported with modest results.
• Audiology, growth and developmental review where indicated. Genetic counselling.

Monitoring. Review yearly in childhood.

Referral and escalation. Dermatology; genetics and audiology if relevant.