Unusual Cases from the Genodermatosis Clinic in London

In 2015, the Genodermatosis Clinic at St John’s Institute opened the doors of its dedicated pediatric clinic. Jemima Mellerio, MD, FRCP, St John’s Institute of Dermatology in London, United Kingdom, joined the 2023 Society for Pediatric Dermatology Meeting in Asheville, North Carolina, on July 16 to review some of the cases from the clinic.

The clinic was built with the idea of creating a community for those with rare skin diseases, so they could meet others who shared their experiences, discuss their journeys, and feel less isolated.

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The first case Mellerio reviewed was a woman who had been diagnosed with autosomal recessive congenital ichthyosis as a child when the extensive genetic testing done today was not available. The woman’s husband is her second cousin, which led to discussions about the possibility of passing along ichthyosis to their child. Genetic testing revealed she had a keratin 10 mutation (+/- IVS6-2A>G), ichthyosis with confetti, an autosomal dominant ichthyosis, not recessive.

With the risk of passing along the disease at 50%, she had an embryo transfer and now has a healthy daughter.

Another case involved a 3-month-old girl that had been born with dry, red, cracked skin on her hands and feet and scaly areas in lines on her trunk and limbs. By 4 months, the ichthyosis had almost completely cleared. Genetic testing revealed that she was heterozygous for the emopamil binding protein gene and confirmed the diagnosis of Conradi-Hünermann syndrome (chondrodysplasia punctata type 2).

The X-linked dominant condition has several characteristics including skeletal abnormalities, cataracts, punctate stippling of bones, ichthyosiform erythroderma, and patchy hair along the lines of Blaschko.

The next case Mellerio reviewed was a 7-year-old girl of Afghani parents who had been born with superficial erosion on her arm. Doctors suggested epidermolysis bullosa (EB) could be the cause but that was not confirmed. She developed mild hyperkeratosis at the extensors of her joints and slightly thick nails.

When Mellerio’s team first saw her at age 7, the diagnosis was superficial epidermolytic ichthyosis. They sequenced keratin 2, keratin 1, keratin 10, 6A, 6B, 16 and 17, but all were negative. At each visit, the girl’s lips were very dry and cracked, and her skin exhibited superficial peeling. Her nails looked normal, but white, and she had thick areas of hyperkeratosis on the backs of her knuckles. She also developed small, punctate keratosis studded over her palms and soles.

The combination of features led to a diagnosis of a newer condition, PLACK syndrome, which stands for peeling skin, leuconychia, acral keratoses, cheilitis, and knuckle pads, and affects the calpastatin gene.

In another case, Mellerio discussed the joys of telemedicine. A British man living in South Africa sent her an email and photos of his 9-year-old son who had experienced blistering on his hands, elbows, knees, and face since he was 18 months old. The boy’s voice was also hoarse. The boy had seen doctors in South Africa when he was 5 years old and had a skin biopsy and porphyrin screen, which were negative.

The boy had been given various treatments between ages 5 and 9, but nothing was successful. The diagnosis that had been made was EB acquisita, but Mellerio questioned that assessment. He was being treated with prednisolone, azathioprine, and dapsone, but still had blisters, and the boy’s father asked if his medications should be changed to better manage the disease.

When she looked at photos of the boy’s face, Mellerio could see blistering, waxy thickening, and moniliform blepharosis, which led to her diagnosis of lipoid proteinosis. As the disease progresses, hyaline material is deposited in mucosae, causing thickened sublingual frenulum and laryngeal involvement. The hyaline material can also develop in organs, causing mild developmental delays, seizures, neuropsychiatric problems, and drusen.

Mellerio then went on to discuss a case she called “A Wolf in Sheep’s Clothing.” A 6-month-old girl was referred to their pediatric EB center because her finger and toenails were falling out after minor “knocks,” such as rubbing her hands against the crib. Her skin was fine and the clinicians wondered if it could be junctional EB or laryngo-onychocutaneous syndrome. Her parents were second cousins and that was considered in diagnosing, as well.

Doctors took a biopsy of her thigh for direct immunofluorescence and electron microscopy and those test results were normal. The biopsy site was not healing and the problems with her nails continued to progress. The girl was admitted for observation and better wound care, which was when one of the nurses noticed the mother picking at the biopsy site. This led to safeguarding and child protective measures.

The girl was discharged to foster care. After 2 months in foster care, the biopsy site was completely healed, and her nails were growing in. Mellerio explained that Munchausen by proxy is something pediatric dermatologists need to be aware of as a possible explanation when children are brought into the clinic.

Reference

1. Mellerio J. Hurwitz lecture part 2 – Illuminating cases from the genodermatosis clinic. Presented at the 2023 Society for Pediatric Dermatology Meeting; July 13-16, 2023. Asheville, NC.