A seborrheic keratosis is a very common benign growth of the outer skin layer that appears in middle and older age. It looks waxy and stuck on, needs no treatment, and the main task is telling it apart from skin cancer.
Key symptoms
- Slowly growing brown, tan or black spots, often several
- Rough or waxy surface that may itch
- Catches on clothing and can bleed when irritated
- Concern about appearance or a change in a spot
What you find on exam
- Well-defined, raised, waxy plaques that look pasted on
- Color from skin tone to dark brown, with a warty or crumbly surface
- Common on the chest, back, face and scalp
- Dermoscopy: milia-like cysts and comedo-like openings
- Check each spot with the ABCDE rule for melanoma
Tests
- Usually none; diagnosis is clinical and by dermoscopy
- Shave or punch biopsy if the lesion looks atypical, bleeds or changes
- Look for cancer if many appear suddenly (sign of Leser-Trelat)
Treatment basics
- Reassurance; no treatment is needed
- Cryotherapy with liquid nitrogen for irritated or unwanted lesions
- Curettage or shave removal, which also gives tissue for pathology
- Electrodesiccation or laser for selected lesions
Red flags
- Irregular border, several colors, fast growth or bleeding without trauma
- Sudden eruption of many lesions, which can mark an internal cancer
- Lesion that ulcerates or does not look like the others
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.