- Introduction to dermatoscopy CME
- Dermatoscopic features CME
- Three-point checklist CME
- Dermoscopy of benign melanocytic lesions CME
- Dermoscopy of atypical naevi CME
- Dermoscopy of malignant melanoma CME
- Dermatoscopy of seborrhoeic keratosis CME
- Dermoscopy of basal cell carcinoma CME
- Dermatoscopy of squamous cell carcinoma CME
- Dermatoscopy of other non-melanocytic lesions
- First step algorithm CME
- Pattern analysis CME
- Other algorithms for melanocytic lesions CME
- The dermatoscopy report CME
- Melanocytic naevi: new classification CME
- Dermoscopy of the nail CME
- Dermatoscopic-histologic correlation CME
- Blue naevus images CME
- Globular (congenital) naevus images CME
- Reticular (acquired) naevus images CME
Developed in collaboration with the University of Auckland Goodfellow Unit in 2007.
Author: Hon A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand, 2008.
Images have been sourced from the following:
- Hon Assoc Prof Amanda Oakley
- The Department of Dermatology, Waikato Hospital
- MoleMap New Zealand (with permission)
- Dr Richard Williamson and coworkers (as indicated in dermatoscopic-histology page*)
Dermoscopy of seborrhoeic keratosis CMENext Previous
- Describe dermoscopic features of seborrhoeic keratosis
Dermoscopy is useful to distinguish pigmented non-melanocytic lesions from benign and malignant melanocytic lesions. There are specific features that help to distinguish seborrhoeic keratosis from basal cell carcinoma and melanoma. However, the distinction is not always possible and it may be necessary to excise some clinically atypical but histologically benign lesions.
The ‘wobble sign’ may be useful to distinguish a papillomatous melanocytic naevus from a stable seborrhoeic keratosis.
Dermoscopic features of seborrhoeic keratosis
Seborrhoeic keratoses typically reveal dermoscopic features that are fairly specific for the diagnosis. However, on occasions, melanocytic lesions, especially dermal naevi, congenital naevi, Spitz naevi and nodular melanoma, may have similar features and can be just as difficult to distinguish from seborrhoeic keratoses by dermoscopy as clinically.
Seborrhoeic keratoses can have an irregular structure and multiple colours (skin coloured, pink, grey, yellow, tan, dark brown, black, bluish).
Typical dermoscopic features include:
- Milia-like cysts – there are two types:
- Tiny white starry
- Larger yellowish cloudy
- Irregular crypts
- Blue-grey globules
- Light brown fingerprint-like parallel structures
- ‘Fat fingers’ (the gyri of a cerebriform surface)
There may also be a faint network or pseudonetwork. Blood vessels can be prominent in some seborrhoeic keratoses, tending to arise as tiny hairpin shaped capillaries surrounded by a halo within a lobule.
Dermoscopy of seborrhoeic keratoses
Tanning cream in crypts
Starry and cloudy milia-like cysts
Hairpin blood vessels
Exophytic papillary structures
Identification of seborrhoeic keratoses by Chaos and Clues method
Seborrhoeic keratoses demonstrate "chaos" by modified pattern analysis, ie, they often have asymmetry of colour and structure on dermatoscopy — like pigmented skin cancers. Clinical clues to seborrhoeic keratoses are:
- Multiple grouped similar lesions
- Stuck-on lesion
- Waxy or scaly surface
Dermatoscopic clues to seborrhoeic keratoses by modified pattern analysis are:
- Multiple orange clods
- Multiple white clods
- Thick curved lines
- Sharply demarcated border over total periphery
If features are equivocal, excise the lesion. Partial biopsy may be acceptable if low-risk lesions, providing full excision is arranged should the atypical lesion prove to be melanocytic.
Evaluate 20 pigmented seborrhoeic keratoses by dermoscopy. What proportion contain each of the following features:
- Pigment network
- Milia-like cysts
- Irregular crypts
- Multiple colours (3 or more)