To describe morphological features of seborrheic keratosis as seen by dermoscopy and to investigate their prevalence.
Prospective cohort study using macrophotography and dermoscopy for the documentation of seborrheic keratosis.
Seborrheic keratoses were prospectively collected in 2 sites: a private practice in Plantation, Fla (site 1), and the Department of Dermatology at the University Hospital Geneva in Switzerland (site 2).
A total of 203 pigmented seborrheic keratoses (from 192 patients) with complete documentation were collected (111 from site 1 and 93 from site 2).
Screening for new morphological features of seborrheic keratosis and evaluation of all lesions for the prevalence of these criteria.
Main Outcome Measures
Identification of new morphological criteria and evaluation of frequency.
A total of 15 morphological dermoscopic criteria were identified. Standard criteria such as milialike cysts and comedolike openings were found in a high number of cases (135 and 144, respectively). We found network and networklike structures to be present in 94 lesions (46%). Using standard diagnostic criteria for seborrheic keratosis, 30 lesions would not have been diagnosed as such.
The classic dermoscopic criteria for seborrheic keratosis (milialike cysts and comedolike openings) have a high prevalence but the use of additional dermoscopic criteria such as fissures, hairpin blood vessels, sharp demarcation, and moth-eaten borders improves the diagnostic accuracy. The proper identification of pigment network and networklike structures is important for the correct diagnosis.