Dermatology · Benign Skin Lesions
The facts most likely to be tested
Seborrheic keratoses present as well-demarcated, tan-to-brown plaques with a characteristic stuck-on appearance.
Dermoscopy reveals horn cysts and comedo-like openings which are pathognomonic for these benign lesions.
The Leser-Trélat sign is the sudden eruptive appearance of multiple seborrheic keratoses associated with an underlying internal malignancy, most commonly gastric adenocarcinoma.
Histopathology demonstrates hyperkeratosis, acanthosis, and papillomatosis with characteristic horn cysts.
These lesions are benign and do not require treatment unless they are symptomatic, irritated, or cosmetically bothersome.
Treatment options for symptomatic lesions include cryotherapy, curettage, or shave excision.
Seborrheic keratoses are most common in older adults and typically appear on the trunk, face, and upper extremities.
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A 68-year-old male presents to the clinic for a routine physical. He reports the recent appearance of numerous dark, waxy lesions on his back and chest over the past three months. Physical examination reveals multiple hyperpigmented, velvety plaques with a stuck-on appearance scattered across his torso. Dermoscopy of the lesions shows horn cysts and comedo-like openings. The patient also reports a 10-pound unintentional weight loss and persistent epigastric discomfort.
What is the most likely diagnosis and the most appropriate next step in management?
Seborrheic keratosis with suspected Leser-Trélat sign; perform an age-appropriate cancer screening, specifically for gastrointestinal malignancy.
The patient's presentation of eruptive seborrheic keratoses (Leser-Trélat sign) in the setting of weight loss and abdominal symptoms is highly suggestive of an underlying internal malignancy.
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Etiology / Epidemiology
Common benign epidermal tumor in older adults; etiology is idiopathic but linked to FGFR3 mutations.
Clinical Manifestations
Well-demarcated, stuck-on appearance with a velvety or warty surface; often described as having a greasy texture.
Diagnosis
Clinical diagnosis; shave biopsy is the gold standard if malignancy is suspected.
Treatment
No treatment required; cryotherapy or curettage for cosmetic concerns or irritation.
Prognosis
Benign; sudden onset of multiple lesions may indicate Leser-Trélat sign, a paraneoplastic syndrome.
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Epidemiology & Etiology
Extremely common in patients >50 years old, with prevalence increasing with age. While the exact cause is unknown, somatic mutations in the FGFR3 gene are frequently identified. There is no known association with UV exposure, unlike other common skin neoplasms.
Pertinent Anatomy
These lesions arise from the epidermis, specifically the proliferation of immature keratinocytes. They are typically located on the trunk, face, and upper extremities, sparing the palms and soles.
Pathophysiology
The lesion represents a benign proliferation of keratinocytes and melanocytes. Histologically, they exhibit hyperkeratosis, acanthosis, and the presence of horn cysts. These cysts are pathognomonic and represent invaginations of the keratinizing epithelium.
Clinical Manifestations
Lesions present as tan, brown, or black papules/plaques with a stuck-on appearance. They often have a velvety or greasy surface texture. Sudden eruptive onset of numerous lesions, known as the Leser-Trélat sign, warrants an age-appropriate cancer screening for internal malignancy, most commonly gastric adenocarcinoma.
Diagnosis
Diagnosis is primarily clinical based on the classic morphology. If the lesion is inflamed, bleeding, or has irregular borders, a shave biopsy is the gold standard to rule out melanoma or squamous cell carcinoma.
Treatment
Treatment is purely elective for cosmetic reasons or if the lesion is chronically irritated. Cryotherapy with liquid nitrogen is the most common office-based procedure. Avoid aggressive excision if the diagnosis is uncertain, as this may delay the identification of a malignant lesion.
Prognosis
These are strictly benign lesions with zero malignant potential. Patients should be monitored for the Leser-Trélat sign, which requires a full systemic workup for underlying malignancy if identified.
Differential Diagnosis
Melanoma: irregular borders and color variegation
Actinic Keratosis: sandpaper-like texture and premalignant
Dermatosis Papulosa Nigra: small, hyperpigmented papules on the face of darker-skinned individuals
Pigmented Basal Cell Carcinoma: pearly, rolled borders with telangiectasias
Skin Tag: pedunculated, soft, and flesh-colored