Benign Skin Tumours

Benign skin tumours are seen commonly in primary care, and an ability to recognise, treat and discriminate them from more serious or malignant dermatological disease is an essential skill for a general practitioner. It is also important for the primary care practitioner to be aware of the limits of their knowledge in this field, and to biopsy lesions where they have any uncertainty of their nature, after assessing the history of the lesion's appearance and growth, and examining it.¹ Benign skin lesions can be a reason for a consultation, be discovered serendipitously by a healthcare practitioner, or be a "whilst I'm here, doctor" appendage to another medical problem. In each case, assessment should be thorough, to avoid the danger of missing a more sinister lesion.

Experience in Australia, the state with the world's highest incidence of skin cancer, shows that adequately trained primary care practitioners in open-access skin-cancer clinics can diagnose a wide range of skin lesions with high specificity and moderate to high sensitivity.² A useful approach is to subdivide lesions into the categories below, then proceed to achieve a diagnosis on the basis of further discriminating features.

1. Campbell de Morgan's spots, or cherry angiomas, occur in up to 50% of adults.³ They are vascular lesions which appear as round, red, non-blanching papules on the trunk or extremities. They are acquired vascular lesions of unknown aetiology, are asymptomatic and have no known clinical consequences. Treatment is for cosmetic purposes only and may be by laser ablation or electrodessication.¹
2. Sebaceous (senile) hyperplasia is common in middle-aged and older patients. It presents as soft, yellow, dome-shaped papules, some of which are centrally umbilicated. Usually they are up to 5mm in diameter but may occasionally be a few centimetres across. They commonly occur on the face but sometimes affect the vulva. They are of no clinical significance, although they can appear similar to early basal cell carcinomas. Treatment with electrodessication or laser ablation is successful; oral isotretinoin has been used in patients with multiple lesions. Biopsy may be required if the diagnosis is uncertain.
3. Dermatofibromas may be a benign tumour, or may represent a fibrous reaction to minor trauma, insect bites etc. They are firm raised papules or nodules and may vary in colour from brown to purple and red. They occur anywhere, but are seen most commonly on the lower limb. Fitzpatrick's sign may be used to aid diagnosis (dimpling of the lesion beneath the skin when subject to bilateral compression, i.e. gently pinching the lesion on either side). The lesions may resemble melanomas, so biopsy may be necessary to confirm the diagnosis. Occasionally the lesion may be removed for cosmetic reasons. Multiple dermatofibromas may be seen in association with autoimmune disorders such as systemic lupus erythematosus, or in patients who are immunocompromised.

1. Seborrheic keratoses are brown or black lesions which look as though they have been 'stuck on' to the surface of the skin. They occur most commonly on the trunk and scalp, but may be found anywhere. The incidence of the lesions increases with age. Their border is usually well demarcated and they have a rough surface, generally ranging in size from 2mm or so across to 2–3 cm across. They may be mistaken for melanomas, although melanomas have a greater range of colour within them whereas seborrheic keratoses are usually a relatively uniformly brown or black.
   
   They are usually asymptomatic but may itch or become inflamed after friction from clothing. Biopsy should be undertaken if the diagnosis is in any doubt. They may be treated for cosmetic reasons with cryotherapy,but because of the danger of misdiagnosis of a melanoma, they are best excised and sent for histological analysis. A sudden onset or increase in the number of lesions may signal an underlying malignancy, usually of the stomach, colon or breast – this is known as Leser-Trelat sign, a paraneoplastic dermatosis.^4,5
   
   
   Typical appearance of seborrhoeic keratoses
   
   
   
   
   
   
2. Keratoacanthomas are rapidly growing papular lesions, often with a central umbilicated keratinous core which may be expelled after several weeks leaving a hypopigmented scar. They are usually single and occur in sun-exposed areas, mainly in older patients. It is uncertain whether they are truly benign, or whether they have malignant potential. Total excision is the treatment of choice, as they are histologically similar to squamous cell carcinoma and tend to leave a prominent scar after they have undergone spontaneous involution. Smaller lesions can be treated with electrodessication and curettage or blunt dissection. Radiotherapy is an option for patients with recurrence or large lesions. Intralesional fluorouracil is a treatment option where there is a large lesion in an area on which it would be difficult to achieve excision with a good cosmetic result, e.g. the eyelids or nasolabial fold.⁶
   
   
   Typical appearances of keratoacanthoma
   
   
   
   
   
   
   
   
   
3. Acrochordons (skin tags) are found in approximately 25% of people, the numbers increasing with age and obesity. They are an area of hyperplastic epidermis and are frequently found in areas where friction occurs, e.g. the neck, axillae and inguinal region. They are often pedunculated with a very narrow stalk but can, on occasion, be sessile. They may be treated for cosmetic reasons or because of irritation, either by electrocauterisation, cryotherapy or scissor excision at the base if they are pedunculated. This can normally be achieved without the need for local anaesthesia. They are of no pathological significance in adults, but in children may herald the development of nevoid basal cell carcinoma syndrome.⁷

1. Lipomas are the most commonly seen subcutaneous tumours. They may occur anywhere on the body, are made up of adipocytes, and have a firm rubbery consistency. The great majority are less than 5cm in diameter, but some may grow larger than 20cms in diameter.They are usually asymptomatic, although may cause symptoms due to mechanical pressure on underlying structures such as nerves. They are normally solitary lesions, and removal is not generally required for other than cosmetic reasons. As lipomas do not invade the surrounding tissues, they are readily "shelled out" during excision or they may be manually squeezed out through a small incision. Lipomas which occur on the thigh and are greater than 5cm in diameter should be referred for specialist opinion to rule out liposarcoma.
2. Epidermoid (sebaceous) cysts are round cysts filled with keratin and which communicate with the skin through a small round keratin filled plug. The term sebaceous is a misnomer as the sebaceous glands do not form any part of the lesion. They have also been termed inclusion cysts and epidermal inclusion cysts. They range in size from a few millimetres to several centimetres and commonly occur on the face, back and chest. Rupture of the cyst wall commonly occurs resulting in an inflammatory reaction. They may be removed either because of recurrent infection, or because of their appearance. They may either be removed intact, or by expressing the contents of the cyst through a small incision, and then removing the cyst wall.