What evaluation and management is recommended for an adult who develops sudden, numerous eruptive seborrheic keratoses (Leser‑Trélat sign)?

Eruptive Seborrheic Keratoses (Leser-Trélat Sign)

When an adult develops sudden, numerous eruptive seborrheic keratoses, perform an immediate and thorough malignancy workup focusing on gastrointestinal and breast adenocarcinomas, as this represents the Leser-Trélat sign—a paraneoplastic phenomenon associated with internal malignancy in the majority of cases.

Clinical Recognition and Significance

The Leser-Trélat sign is characterized by the abrupt appearance and rapid increase in number and/or size of seborrheic keratoses over weeks to months 1, 2. This cutaneous finding typically precedes, coincides with, or follows the diagnosis of internal malignancy 1. The associated tumors are usually aggressive and portend poor prognosis 3.

Key clinical features to document:

• Timeline of onset (sudden vs. gradual)
• Rate of progression (weeks to months suggests true sign)
• Distribution pattern (trunk, back, extremities)
• Associated inflammation (may be an early indicator) 4

Mandatory Malignancy Evaluation

Perform the following workup immediately:

Primary Focus Areas

• Gastrointestinal tract adenocarcinomas (most common association) 5, 2

  • Colonoscopy for colon cancer screening
  • Upper endoscopy if indicated
  • Tumor markers: CA 19-9, CEA

• Breast adenocarcinoma (second most common) 5

  • Mammography and breast examination

• Other adenocarcinomas:

  • Prostate (PSA in men) 5
  • Ovarian (CA-125, pelvic ultrasound in women) 1
  • Lung (chest CT if risk factors present) 6

Imaging Studies

• CT chest/abdomen/pelvis with IV contrast
• Age-appropriate cancer screening if overdue

Important Clinical Caveats

The "pseudo-sign" of Leser-Trélat exists 7, 3. This presents identically but without underlying malignancy. However, you cannot assume this diagnosis initially—malignancy must be actively excluded through comprehensive workup 3.

Non-malignant associations reported:

• HIV infection 8
• HPV infection 8
• COVID-19 infection (recent case reports) 8
• Idiopathic in healthy individuals 7

Management Algorithm

1. Document the eruption: Photograph lesions, note distribution and timeline
2. Complete malignancy workup (as outlined above)
3. If malignancy identified: Treat the underlying cancer; skin lesions may or may not improve with cancer treatment 6
4. If workup negative:
   • Repeat evaluation in 3-6 months
   • Maintain high index of suspicion
   • Consider viral etiologies (HIV, COVID-19)
   • Symptomatic treatment of bothersome lesions with cryotherapy or shave removal 3

Treatment of Skin Lesions

Do not delay malignancy workup to treat skin lesions. Symptomatic seborrheic keratoses can be managed with:

• Cryotherapy for smaller lesions
• Shave removal under local anesthesia for larger lesions where clothing causes irritation 3

Critical point: Skin lesions improve after cancer treatment in only approximately 50% of cases 6. Even with successful cancer resection, seborrheic keratoses may persist or only partially improve 5, 6.

Follow-Up Strategy

• If initial workup negative: Re-evaluate every 3-6 months for first 2 years
• Monitor for new symptoms suggesting occult malignancy
• Repeat age-appropriate cancer screening
• Document any changes in lesion behavior

The presence of inflammatory changes within individual seborrheic keratoses may represent an early sign of Leser-Trélat syndrome, potentially allowing earlier cancer detection 4.