Benign Pigmented Skin Lesions

FOCUS | CLINICAL

Benign pigmented skin lesions

Philip Clarke PIGMENTED SKIN LESIONS are extremely do occasionally arise within a lesion. common, with almost all patients having Individual lesions may also become a number of pigmented lesions on their uncomfortable or unsightly, and treatment Background Benign pigmented skin lesions are skin. When considering their various of such lesions is often appropriate. extremely common. Such lesions are characteristics, it is useful to divide these seen every day in general practice. lesions into melanocytic, keratinocytic, Basal cell carcinomas/Bowen’s disease vascular and reactive lesions. Some basal cell carcinomas and in situ Objectives squamous cell carcinomas may be quite The objectives of this paper are to develop a framework that may be used heavily pigmented, which may mask the Keratinocytic lesions to evaluate pigmented skin lesions and diagnosis (Figures 2 & 3). Dermoscopy will a strategy for dealing with pigmented Seborrhoeic keratosis usually reveal atypical blood vessels and lesions, outline the conditions that A very common lesion is the seborrhoeic characteristic pigment patterns to prompt improve the diagnosis of pigmented keratosis (Figures 1–3). Seborrhoeic the diagnosis.1 lesions (eg good lighting, careful keratoses may start quite early in life, inspection and dermoscopy), and and it is not uncommon to find them on Epidermal naevus increase clinician confidence in identifying pigmented lesions with teenagers. They tend to become larger This type of naevus is formed by concerning features. and more numerous with age. The overgrowth of one or more components of pigment may vary from skin-coloured to the epidermis. The lesions are often warty Discussion pink, brown or black. Most seborrhoeic and hyperpigmented. They are often linear. Regular assessment of pigmented skin lesions during patient consultations, keratoses have a typical appearance and Some examples include sebaceous naevus including in an opportunistic fashion, texture and characteristic dermoscopic (often found on the scalp) and Becker will increase diagnostic acumen and features.1 However, care should be naevus (usually around the shoulder). help to identify potentially problematic taken with any seborrhoeic keratosis These are generally isolated abnormalities lesions, and may improve patient that is unusual. Even very experienced but are sometimes part of a congenital awareness of lesions on their skin. clinicians are occasionally misled by syndrome. This possibility needs to be kept such lesions, which may turn out to be a in mind if there are other health issues for pigmented patch of Bowen’s disease or the child, or the naevus is extensive. a melanoma. If there is significant doubt about a seborrhoeic keratosis, the lesion Freckles and lentigines should be biopsied or carefully reassessed Freckles are also extremely common. in eight weeks, or the patient sent for a Childhood freckles are induced by sun second opinion. Even though seborrhoeic exposure and are more common in keratoses are quite benign, malignancies fair-skinned people, especially those with

364 | REPRINTED FROM AJGP VOL. 48, NO. 6, JUNE 2019 © The Royal Australian College of General Practitioners 2019 BENIGN PIGMENTED SKIN LESIONS FOCUS | CLINICAL

red hair. The colour of freckles is due to of melanoma developing in any particular extra pigment induced by sun exposure, naevus is in the order of 1 in 10,000.2 and not due to an increase in the number Important clues to malignancy include of melanocytes. Freckles often slowly unusual changes in colour or shape, and reduce with age and sun protection. They ongoing change in a mole. tend to fade in the winter. Adult lentigines Dysplastic naevi are difficult to often appear later in life on the chronically accurately define, and a number of exposed areas of the hands and face. These attempts have been made using clinical, tend to be larger than childhood freckles. histological and genetic criteria. However, There is epidermal hyperplasia and an a useful practical definition for general increase in the number of melanocytes. practice is an unusual-looking mole that is They tend not to fade in the winter. If any stable. Dysplastic naevi are not particularly such lentigo on the face continues to grow more susceptible to malignant change, and become irregular, lentigo maligna but they are a potentially important clue melanoma needs to be considered. to overall melanoma risk. There is a One very striking form of freckle is significant correlation between having five the inkspot. This appears as a very dark, or more dysplastic naevi and the lifetime 3 irregular freckle on a sun damaged area of risk of melanoma. Figure 1. Multiple pigmented seborrhoeic skin such as the shoulders or neck. Despite Blue naevi are a distinctive form of keratoses being very dark and irregular, it has a very melanocytic naevus. A blue naevus typical appearance on dermoscopy,1 is typically has a steely blue appearance quite stable and does not require removal with some characteristic features on if it remains stable. dermoscopy.1 Malignant transformation Isolated melanocytic macules are is uncommon, but any change in a blue quite common, especially on the lip. If naevus should prompt careful evaluation. there are several melanocytic macules The number of moles on a patient is appearing early in life, this may indicate also important. Having 100 or more moles an underlying syndrome. For instance, relates to a significantly higher risk of several macules on the lips and around and melanoma.3 A very important phenotype to in the mouth may signify Peutz-Jeghers recognise in general practice is the patient syndrome. Lifelong follow-up is required with 100 or more moles, several dysplastic for such patients because of the extremely naevi and a family history of melanoma. high likelihood of cancer, especially of the These patients have a very high risk of Figure 2. Pigmented seborrhoeic keratosis to gastrointestinal tract. melanoma and should be strongly advised the left and linear red basal cell carcinoma to have a regular skin check.3 to the right

Melanocytic lesions Moles (melanocytic naevi) are also Vascular lesions extremely common. Haemangiomas are common in both Congenital melanocytic naevi occur in children and adults (Figure 4). Childhood approximately 1 in every 100 babies.2 The lesions usually clear spontaneously after risk of developing melanoma is very low, a few years, but adult lesions persist and even in very large naevi.2 may become very numerous. Most are a Most melanocytic naevi appear within very straightforward clinical diagnosis the first few years of life, but new naevi (eg cherry angioma), but some adult may continue to appear throughout haemangiomas may be very dark and may life. More naevi will develop if there present as a concerning black lesion. If is increased sun exposure, especially the blood in the haemangioma becomes excessive exposure in the first 10 years slow moving or thromboses, the very dark of life. Excessive sun exposure in this purple colour may appear black. There time significantly increases the risk of is a very characteristic appearance on melanoma later in life.3 dermoscopy.1

Taking into consideration the number One uncommon but extremely Figure 3. Pigmented basal cell carcinoma with of naevi in the general population and the important red lesion to be aware of is an surrounding pigmented seborrhoeic keratoses number of melanomas diagnosed, the risk amelanotic melanoma. These melanomas

often have a very fast growth rate and the eczema. Lichen planus usually has Key points have a poorer prognosis than most a violaceous or brown pigmentation. • Benign pigmented skin lesions melanomas. Any firm red raised lesion Both conditions typically have lesions are extremely common in general that has persisted for four weeks should be appearing in a symmetrical pattern, but practice and will be seen every day biopsied.3 Such lesions may present as a careful attention should be taken with during consultations. presumed abscess, but if no pus is drained, isolated lesions. • A quick but careful examination aided the lesion should be biopsied (ie removed by dermoscopy will rule out almost all entirely). serious lesions. Kaposi sarcoma is a vascular/lymphatic Examination and dermoscopy • Care needs to be taken with lesions that lesion that was rare prior to the increase in Diagnosing pigmented lesions is enhanced are not completely typical. prevalence of human immunodeficiency by good lighting, a small amount of • It is important to take note of a patient’s virus. The diagnosis should be kept in mind magnification (binocular loupe) and concern about a particular lesion, when a vascular plaque or nodule is found. dermoscopy. Useful information is also especially if it is an ongoing concern; obtained from feeling and stretching such concerns should not be ignored lesions. Rubbing lesions with an alcohol or dismissed. Reactive lesions hand rub prior to dermoscopy is a useful Dermatofibromas way of highlighting vascular changes. Dermatofibromas are quite common, Familiarity with dermoscopic findings Author especially on the lower limbs (Figure 5). and regular use of the dermatoscope Philip Clarke BMEDSc, MBBS, FRACGP, DFM, DDSc, FAAD, Dermatologist, Senior Clinical Lecturer, The typical clinical finding is a very are important skills for the general Department of Medicine, University of Tasmania, Tas; firm nodule that puckers when pressed practitioner.4 Visiting Dermatologist, Launceston General Hospital, Tas. [email protected] from the sides. Some are quite deeply Competing interests: None. pigmented. They may vary in colour from Funding: None. skin-coloured to pink, red, violaceous or Biopsy Provenance and peer review: Commissioned, brown. Dermoscopy may show a typical Most pigmented lesions will not need to externally peer reviewed. pattern.1 Dermatofibromas are stable and be removed. However, if there is concern benign, but rarely there can be malignant about the possibility of melanoma, it is References transformation (dermatofibrosarcoma important to remove the whole lesion 1. Braun, RP, Rabinovitz HS, Oliviero M, Kopf AW, Saurat JH. Dermoscopy of pigmented skin 3 prutuberans). If a lesion is enlarging, it with a thin margin (2 mm). Punch and lesions. J Am Acad Dermatol 2005;52(1):109–21. should be removed. shave biopsies should not be performed on doi: 10.1016/j.jaad.2001.11.001. suspicious pigmented lesions.3 Histological 2. Alikhan A, Ibrahimi OA, Eisen, DB. Congenital melanocytic nevi: Where are we now? Part I. Eczema/lichen planus interpretation and proper diagnosis is Clinical presentation, epidemiology, pathogenesis, Small nodular patches of eczema may difficult, and malignant change may only histology, malignant transformation, and neurocutaneous melanosis. J Am Acad become quite pigmented. This is probably be present in part of the lesion, which may Dermatol 2012;67(4):495.e1–17. doi: 10.1016/j. triggered by repeated scratching of be missed by partial biopsy. jaad.2012.06.023.

Figure 4. Dark capillary haemangioma Figure 5. Dermatofibroma with pale centre and peripheral pigment

366 | REPRINTED FROM AJGP VOL. 48, NO. 6, JUNE 2019 © The Royal Australian College of General Practitioners 2019 BENIGN PIGMENTED SKIN LESIONS FOCUS | CLINICAL

3. Australian Cancer Network Melanoma Guidelines Revision Working Party. Clinical practice guidelines for the management of melanoma in Australia and New Zealand. Wellington: New Zealand Guidelines Group, 2008. Available at https://melanomapatients. org.au/wp-content/uploads/2017/05/cp111.pdf [Accessed 2 May 2019]. 4. Royal Australian College of General Practitioners. Guidelines for preventive activities in general practice, 9th edn. East Melbourne: Vic: RACGP, 2018. Available at www.racgp.org.au/FSDEDEV/ media/documents/Clinical%20Resources/ Guidelines/Red%20Book/Guidelines-for- preventive-activities-in-general-practice.pdf [Accessed 10 April 2019]. correspondence [email protected]