Rothmund-Thomson Syndrome
Rothmund-Thomson syndrome (RTS), also known as congenital poikiloderma, is a very rare autosomal recessive disorder. Its core feature is poikiloderma, a mixed pattern of skin changes that appears very early in childhood, together with skeletal abnormalities, defects of the hair and nails, and a high risk of malignant bone cancer (osteosarcoma).
Genetically, RTS (especially type 2) is caused by loss-of-function mutations in both copies of the RECQL4 gene (chromosome 8q24.3). This gene encodes RECQL4, a RecQ-family helicase that is essential for starting DNA replication, keeping the genome stable and repairing DNA breaks. Without enough RECQL4, cells become highly sensitive to ultraviolet (UV) radiation and other agents that break DNA. Mutations build up faster, keratinocytes and fibroblasts undergo programmed cell death (apoptosis) more readily, and the path to cancer is set in motion.
At Haute-Derma, managing RTS means recognizing poikiloderma early, restoring the barrier of light-sensitive skin, and working closely with imaging and orthopedic specialists to screen for bone cancer during the teenage years.
Pathogenesis and Characteristic Clinical Features
Rothmund-Thomson syndrome shows a classic triad: poikiloderma – skeletal abnormalities – high cancer risk:
- Progression of Poikiloderma:
- Early phase (3–6 months of age): sudden onset of red, slightly swollen patches on both cheeks (resembling a rash or a butterfly pattern), which then spread to the nasolabial folds, chin and forehead and to sun-exposed areas such as the forearms and lower legs.
- Chronic phase: the redness gradually evolves into the mixed picture of poikiloderma: superficial dilated vessels (telangiectasia), a net-like mix of darker and lighter spots, and pinpoint skin atrophy.
- Photosensitivity: present in about 30–50% of patients; sun exposure triggers severe flares of redness and blistering.
- Skeletal and Growth Abnormalities (Skeletal Dysplasia):
- Abnormal development of the upper limb bones: missing or underdeveloped radius (radial ray defects) and malformed or absent thumbs.
- Small or absent kneecaps, and progressive short stature due to growth plate problems.
- Early osteoporosis and an increased risk of pathologic fractures.
- Hair, Nail and Tooth Defects:
- Sparse or completely absent eyebrows and eyelashes; thin, fine, brittle scalp hair.
- Nail dystrophy (split, thickened nails) and crooked, missing or poorly enameled teeth.
- High Malignancy Risk:
- Osteosarcoma: develops in about 30% of patients with RTS type 2, peaking between ages 9 and 14.
- Skin cancer: a high risk of squamous cell carcinoma (SCC), basal cell carcinoma (BCC) and melanoma in adulthood, arising on chronic poikilodermatous skin.
RTS Type 1 vs. RTS Type 2
| Feature | RTS Type 1 | RTS Type 2 |
|---|---|---|
| Genetic basis | Not caused by RECQL4 mutations (often linked to ANAPC1) | RECQL4 gene mutations (8q24.3) |
| Frequency | About 30–35% | About 65–70% (most common) |
| Poikiloderma | Typical from early childhood | Typical from early childhood |
| Cataracts | Very common (early onset, age 2–3) | Rare |
| Osteosarcoma risk | Very low or absent | Very high (onset in adolescence) |
| Limb bone abnormalities | Uncommon | Very typical (radius/thumb defects) |
Our Diagnostic Workup at Haute-Derma
- Clinical Criteria:
- Major criteria: poikiloderma starting before age 2; limb bone malformations (especially of the radius/thumb); osteosarcoma at a young age.
- Minor criteria: short stature; loss of eyebrows/eyelashes; juvenile cataracts; nail/tooth dystrophy; photosensitivity.
- Imaging and Dermoscopy (Dermoscopy & HFUS):
- Skin dermoscopy: shows a network of superficial branching or coiled dilated capillaries, interspersed with dot-like depigmented areas and unevenly distributed melanin granules in the epidermis and upper dermis.
- High-frequency skin ultrasound (HFUS, 22–50 MHz): assesses epidermal thinning and changes in the echogenicity of the dermal collagen band.
- Molecular Genetic Testing: NGS sequencing of the RECQL4 gene to identify compound heterozygous or homozygous recessive mutations, which confirms RTS type 2.
- Skeletal Screening: X-rays of the whole upper-limb skeleton, plus ultrasound or MRI if the patient has persistent bone pain, to catch osteosarcoma early.
Treatment and Clinical Management at Haute-Derma
There is currently no treatment that corrects the underlying gene mutation. Our protocol focuses on strict sun protection, non-invasive management of pigment and blood vessels, and a structured schedule of cancer screening:
Sun Protection and Skin Barrier Repair
- Thorough physical sun protection: a broad-spectrum SPF 50+, PA++++ sunscreen with micronized titanium dioxide and zinc oxide to reflect as much UVA/UVB as possible without irritating sensitive skin.
- Protective clothing: we advise UV-protective clothing (UPF 50+), sunglasses, and staying indoors during peak UV hours (10 a.m.–4 p.m.).
- Moisturizing and soothing: repair creams or balms with panthenol (B5), madecassoside and skin-identical ceramides help calm light-induced redness and inflammation.
Controlling Poikilodermatous Vessels and Pigment
- Low-energy intense pulsed light (IPL/BBL): considered carefully for widespread superficial telangiectasia. Suitable cut-off filters (530–590 nm) and active cooling are used to shrink dilated vessels without blistering or secondary heat injury.
- Important caution: we do not use high-energy ablative fractional lasers (CO2/erbium). RTS skin cells repair DNA poorly, so these lasers can cause permanent loss of pigment or trigger chronic ulcers.
Cancer Screening and Multidisciplinary Care
- Skin checks every 3–6 months: full-body dermoscopy to catch precancerous lesions (actinic keratosis) or squamous cell carcinoma (SCC) early.
- Osteosarcoma monitoring: patients with RTS type 2 need close watch for persistent swelling or pain in the long bones (thigh, lower leg). X-ray or MRI is arranged as soon as there is any suspicion.
- Cataract screening (RTS type 1): eye exams every 6 months for young children so cataracts can be found and operated on early, preventing amblyopia.
