Dermatology
Benign Skin Lesions
❍ At a glance
- In New Zealand, where melanoma rates are among the highest in the world, the threshold for dermoscopic assessment or referral should be low whenever a lesion does not fit clearly into a benign category. When in doubt, refer.
- Dermoscopy training significantly improves diagnostic accuracy - GPs who use dermoscopy regularly refer fewer benign lesions and miss fewer malignant ones.1
- Refer urgently (within two weeks) for any pigmented lesion with irregular border, variable colour, diameter >6 mm, or change in size/shape/colour. Non-healing ulcers and any lesion you are uncertain about warrant dermoscopy or specialist review.
- Pyogenic granuloma: rapid growth and easy bleeding can be alarming, but excision is straightforward. Always send for histology to exclude amelanotic melanoma.
Skin lesions are one of the most common presentations in general practice, and the diagnostic task is primarily triage: which lesions are benign and reassurable, which warrant watchful waiting, and which need urgent or semi-urgent referral. In New Zealand, where melanoma rates are among the highest in the world, the threshold for dermoscopic assessment or referral should be low whenever a lesion does not fit clearly into a benign category. When in doubt, refer - the consequences of a missed melanoma or squamous cell carcinoma are significant, and dermatology services accept appropriately uncertain referrals.
❍ Common benign lesions
- Seborrhoeic keratoses (SK) - the most common benign skin tumour in adults over 40. Stuck-on, warty, or velvety plaques ranging from pale yellow to deep brown-black, with a characteristic "crumbly" or matt surface. May appear on any body surface except palms and soles. Dermoscopy shows a well-demarcated border, cerebriform surface, and milia-like cysts - features that reliably distinguish SK from melanoma. Sudden onset of multiple SK (sign of Leser-Trélat) may rarely indicate underlying malignancy. No treatment required for asymptomatic lesions; cryotherapy or curettage for irritated or cosmetically troublesome lesions (patient-funded in most cases).
- Dermatofibroma - firm, slightly raised, pigmented nodule typically on the lower limbs, more common in women. Pinches inward on lateral compression (dimple sign). Dermoscopy shows a central white patch with peripheral pigmentation. No treatment required unless symptomatic; complete excision if removal is desired (recurrence after shave excision is common).
- Epidermoid cysts - smooth, mobile, dome-shaped subcutaneous nodules with a central punctum. Most commonly on the face, trunk, and scrotum. Contents are keratin (not sebum - the term "sebaceous cyst" is a misnomer). Treat inflamed cysts with incision and drainage; complete excision of the cyst wall (including the punctum) prevents recurrence. Antibiotics are not routinely required unless there is surrounding cellulitis. Pilar cysts (similar appearance, often on the scalp, no punctum) are managed the same way.
- Lipomas - soft, mobile, lobulated subcutaneous fat deposits, typically on the trunk, upper arms, or posterior neck. Firm or fixed lipomas, those with overlying skin changes, or those growing rapidly should be referred to exclude liposarcoma (uncommon but important). Routine lipomas can be removed under local anaesthetic in primary care if symptomatic or cosmetically desired.
- Cherry angiomas (Campbell de Morgan spots) - small, bright-red vascular papules on the trunk, appearing in adults from the third decade onwards. Benign proliferation of dermal capillaries; no clinical significance. Distinguish from spider naevi (central arteriole, radiating vessels - may indicate liver disease when multiple). Reassure.
- Pyogenic granulomas - rapidly growing, friable red vascular nodules that bleed easily, often at sites of trauma or during pregnancy. Shave excision and curettage with or without electrocautery is the usual treatment; send for histology to exclude amelanotic melanoma. Recurrence after incomplete removal is common.
- Skin tags (acrochordons) - small, pedunculated soft fibromas in skin folds (neck, axillae, groin, eyelids). Associated with obesity, diabetes, and pregnancy. Treatment by cryotherapy, snipping, or electrocautery - not funded unless causing functional symptoms. Multiple skin tags in unusual distributions warrant consideration of underlying metabolic disease.
❍ When to refer and NZ resources
Refer urgently (within two weeks) for any pigmented lesion with irregular border, variable colour, diameter >6 mm, or change in size/shape/colour (ABCDE criteria remain a useful but imperfect screen). Non-healing ulcers, new lesions with atypical features, or any lesion you are uncertain about warrant dermoscopy or specialist review. Dermoscopy training significantly improves diagnostic accuracy - GPs who use dermoscopy regularly refer fewer benign lesions and miss fewer malignant ones.1
In New Zealand, Te Whatu Ora skin lesion clinics and community dermatology services provide semi-urgent pathways. For rural and provincial practices, teledermatology image review is increasingly available through some DHB or PHO services.