Seborrhoeic Keratosis
Seborrhoeic wart, Basal cell papilloma
A seborrhoeic keratosis showing a typical "stuck on" appearance.
The "flatter type" of seborrhoeic keratosis. Note the greasy appearance of the lesions.
Although the diagnosis is slightly less clear than in Figures 1 and 2, the greasy appearance and pitted "seed-like" areas make the diagnosis of seborrhoeic keratosis most likely.
This lesion is on the scalp of an elderly lady. Once again, the stuck on appearance and "seed-like" adhesions allow the diagnosis of Seborrhoeic keratosis to be made.
This highlights the fact that seborrhoeic keratoses rarely exist in isolation.
This is a closeup of the largest lesion shown above.
Features
Seborrhoeic keratoses are defined as a benign proliferation of epidermal keratinocytes. They present as raised, yellow-brown or black lesions and are often greasy and present in multiple sites. They usually appear on the trunk and vary between 1mm and several centimetres in size. They are often of little concern to the patient, although itching is sometimes a feature.
The most common appearance is a flat, verrucous plaque which appears "stuck on". This is shown in Figure 1. The other type is the flat type of seborrhoeic keratosis, shown in Figures 2 and 6. This type is sometimes confused with the malignant lentigo maligna melanoma.
Incidence
Seborrrhoeic keratoses are very common in white races, developing most commonly in the fifth decade. They are equally prevalent in males and females.
Aetiology
The aetiology is largely unknown. In some rare cases, occurance can be linked with a familial trait which has an autosomal dominant mode of inheritance. Multiple eruption of seborrhoeic keratoses are sometimes linked to an inflammatory dermatosis, severe sunburn or as a manifestation of a visceral malignancy. The latter is usually cancer of the GI tract and is known as the sign of Leser-Trelat. The vast majority of cases, however, are idiopathic and require no further investigation.
Differential Diagnosis
Lentigo maligna melanoma. Actinic keratosis. Early invasive Squamous cell carcinoma.
Treatment
This is an entirely benign lesion and no treatment is required, but if it is causing patient distress then dermal shaving, currettage (with application of superficial styptic) or cryotherapy may be considered. Histology if in doubt, and warn the patient of the high likelihood of recurrence.
