Leser-Trélat Sign
The sign of Leser-Trélat is the rapid, widespread eruption of seborrheic keratoses (SKs) on itchy, inflamed skin, and it is a classic paraneoplastic skin syndrome. Ordinary seborrheic keratoses appear one by one, slowly, as the skin ages. The Leser-Trélat sign is defined instead by a sudden increase in both the number and the size of SKs, with dozens to hundreds appearing within weeks to months, which may point to an advancing cancer hidden inside the body.
About 60–70% of cases are linked to gastrointestinal adenocarcinomas. Stomach cancer is the most common (30–40%), followed by colorectal, pancreatic and liver cancer. The sign has also been reported with blood cancers (non-Hodgkin lymphoma, leukemia) as well as breast and lung cancer.
At the molecular level, the Leser-Trélat sign shares its mechanism with tripe palms. The internal tumor floods the bloodstream with growth factors, particularly transforming growth factor alpha (TGF-alpha), epidermal growth factor (EGF) and insulin-like growth factor 1 (IGF-1). Excessive binding of these factors to EGFR receptors on keratinocytes switches on the MAPK/ERK signaling pathway, driving abnormal proliferation of basaloid cells and producing crops of new seborrheic keratoses on the skin.
Clinical Features and the Paraneoplastic Triad
The Leser-Trélat sign looks quite different from ordinary seborrheic keratoses:
- Speed of onset and number: many small new SKs appear at once, or existing ones suddenly enlarge, spreading over the body within a short period (2–12 weeks).
- Typical distribution: mainly on the trunk (a "Christmas tree" pattern on the back, plus the chest and abdomen), then the armpits, neck, groin and limbs.
- Appearance and inflammation: the growths have a "stuck-on" look with a bumpy surface, ranging from light brown to very dark. Notably, they often sit on a red, inflamed base and itch intensely (pruritus), a reaction to cytokines released by the tumor.
- The paraneoplastic triad: in many complex cases, the Leser-Trélat sign does not appear alone but together with malignant acanthosis nigricans in the skin folds and tripe palms. This trio is a very strong pointer to gastrointestinal cancer.
Leser-Trélat Sign vs. Age-Related Seborrheic Keratosis vs. Actinic Keratosis
| Leser-Trélat sign | Age-related seborrheic keratosis | Actinic keratosis |
|---|---|---|
| Paraneoplastic syndrome linked to internal cancer (stomach, colon, pancreas) | Natural skin aging with local FGFR3/PIK3CA mutations | Precancerous lesion caused by cumulative UV damage |
| Sudden eruption over weeks to months, many at once | Appear gradually and accumulate over many years | Develop slowly on sun-exposed skin |
| Numerous (dozens to hundreds), intensely itchy, red and inflamed | A few scattered lesions, not itchy or inflamed | Rough, sandpaper-like patches, sometimes slightly tender |
| Milia-like cysts, comedo-like openings, brain-like fissures and ridges, inflamed vascular base | Milia-like cysts and clear comedo-like openings | Strawberry pattern with surface scale |
| High risk of gastrointestinal cancer | Benign; no health risk | 5–10% progress to squamous cell carcinoma (SCC) |
Diagnosis and Management at Haute-Derma
When a patient comes in with a sudden crop of unusual keratoses, Haute-Derma follows a rigorous screening process:
Dermoscopy and Superficial Imaging
- Digital dermoscopy: confirms the classic SK features (milia-like cysts, comedo-like openings, and brain-like fissures and ridges) and helps rule out skin cancers such as melanoma or pigmented basal cell carcinoma.
- High-frequency skin ultrasound (HFUS, 22–50 MHz): measures how deep the keratotic layer extends, confirms a clear boundary with the dermis below, and shows any widespread increase in blood vessels.
No Early Cosmetic Procedures
- No CO2 laser or widespread chemical peels: rushing to remove hundreds of keratoses with CO2 laser or peels before the cause is known is a serious clinical mistake. It is painful, carries a high risk of ulceration and hypertrophic scarring on already inflamed skin, and delays the critical window for finding an internal cancer.
- Symptom relief: gentle topical products with urea 5–10%, niacinamide and panthenol soften the scale and ease the intense itching while screening results are pending.
Urgent Referral for Whole-Body Cancer Screening
Patients are placed under dedicated follow-up and urgently referred to a gastroenterology or oncology center for the following workup:
- Full GI endoscopy: upper endoscopy and flexible colonoscopy with insufflation and dye staining to detect adenocarcinomas or malignant polyps early.
- Abdominal imaging: abdominal ultrasound, CT or MRI to screen for pancreatic cancer, liver cancer and other abdominal tumors.
- Serum tumor markers: blood tests for CEA and CA 19-9 (stomach, colon and pancreatic cancer), CA 125 (in women) and AFP.
