Abstract
As part of the holistic approach to their patients, General Dental Practitioners are well placed to identify common skin lesions. Awareness and recognition of worrying lesions allow timely and appropriate referrals for further investigation and treatment. In this paper, we review benign, premalignant and malignant skin lesions, as well as genetic skin conditions. Past medical, family and social history (including sun exposure and previous cutaneous malignancy) is important. Examination includes the lesion, the skin type and the regional lymph nodes. The different common lesions are described, and the epidemiology, clinical features and treatment are discussed.
Screening for skin lesions on the head and neck may be undertaken as part of overall dental care as part of the holistic examination of patients. Particularly with precancerous lesions and skin cancer, an early detection and referral from a dentist can expedite treatment and improve prognosis.
Keywords
Learning Objectives
Understand the risk factors for cutaneous malignancy
Awareness of important warning signs of melanoma
Potential diagnosis relative to lesion appearance (pigmented, red/purple, pearly)
Introduction
Many changes to the skin of the face are the result of chronic sun exposure. Many individuals underestimate their sun exposure; from dog walking to golf, tennis and gardening, the effects of chronic ultraviolet light exposure accumulate with time. Additionally, outdoor occupations, such as construction and the armed forces, increase the risk of photo damage and skin cancer.
Each individual’s response to sunlight is dictated by his or her skin colour, which is predominately a reflection of the amount of melanin in the skin. Individuals with red hair and fair skin burn most easily, and have the highest risk of photo damage and skin cancer, whilst those with very dark brown skin and black hair carry the least risk. The Fitzpatrick classification is useful in describing racial skin pigmentation and relates to the amount of melanin. Type 1 is very light skin, often with freckles, blond hair and blue or green eyes. It burns and rarely tans. Type 2 is fair skin, red or blond hair, blue/brown/green eyes. It usually burns and tans poorly. Type 3 is dark-skinned European (often brown eyes/hair), whilst type 4 describes olive or Mediterranean skin. Type 5 is dark brown skin, (East Asia), burns very rarely and easily tans darkly. Type 6 denotes a very dark or black skin, which rarely burns.
In the older patients, ageing and photoageing lead to course skin, fine and deep wrinkles and mottled pigmentation.
A brief targeted history will help reveal lesions that are concerning (see Table 1 and Figure 1). Some key diagnostic signs are outlined this article.
Key diagnostic features.
Diagnostic tree
Benign skin lesions
Seborrhoiec keratoses
Many patients develop rough, brown, pigmented flat patches on the cheeks, periorbital skin and forehead, which are benign seborrhoeic keratosis. These are harmless lesions, which can be removed with for example laser or chemical peeling. However, it is important to be sure that malignant lesions are excluded before treating anything that is pigmented (see Figure 2).
Seborrhoeic Keratosis.
Lentigo
Lentigo are common lesions that arise in middle age from solar skin damage. They contrast with seborrhoeic keratosis in that they are completely smooth, although in practice, early seborrhoeic keratosis can also be smooth. Lentigo is found on the face and hands. They are well defined, small and surrounded by normal skin. They may fade slightly in winter – essentially, they are like large freckles. It is important to distinguish them from precancerous or cancerous lesions: lentigo maligna melanoma or lentigo maligna. These latter lesions are irregular and have pigmentation that is more variable; they have both lighter and much darker areas within the same lesion.
Haemangioma
Haemangiomas are benign vascular tumours. The most common haemangioma of the face are venous lakes, which are frequently encountered on the lip or ear. These can be treated conservatively, but can be biopsied in case of diagnostic uncertainty. Occasionally, they can become unsightly or bleed. Treatment is surgical, cryotherapy or lasers.
Trichilemmoma
Trichilemmoma are benign tumours from the hair follicle. Clinically, they small and skin coloured raised papules. They can be difficult to differentiate from viral warts or verrucae and could be associated with HPV exposure. They often occur on the nose. They do not require treatment. They can be unsightly and removed with electrocautery or laser. Multiple trichilemmoma can be associated with Cowden syndrome and would require investigation in a specialist unit. 1
Sebaceous hyperplasia
Enlarged sebaceous glands are often seen in the forehead or cheeks of the middle aged or elderly. Clinically they are small, lobulated papules with a yellow hue and with a central hair follicle (see Figure 3). 1
Sebaceous hyperplasia
Premalignant skin lesions
Actinic keratosis/Bowen’s disease
Actinic keratosis are scaly, hyperkeratotic and sometimes pigmented papules. They arise from a diffuse erythematous base on chronically sun-exposed skin. They are often multiple (reflecting the field cancerisation of the skin). On palpation, they have a sandpaper texture. 2 They are more common in the middle aged and in the elderly. 3 Without treatment, these lesions can develop into a SCC with a metastatic potential.
Bowen’s disease (SCC in situ) presents as a well-defined, erythematous and scaly plaque, but its presentation is variable. It represents a SCC that has not yet invaded the dermis.
These lesions can only be distinguished from cutaneous SCC with a biopsy. 3 The main treatment is either topical 5-FU, Imiquinod or Diclofenac or photodynamic therapy (PDT). Depending on the size and location, surgical excision can also be considered. Early results suggest that Vitamin B3 (nicotinamide) is effective in reducing actinic keratosises (see Figures 4 and 5). 4
Actinic keratosis
Actinic keratosis
Lentigo maligna
Lentigo maligna occurs mostly in patients over 40 years old, and peaks among the elderly, with a slight female preponderance. The incidence of lentigo maligna is increasing. 5 Sun exposure, especially in fair-skinned patients, is the main risk factor.
Clinically, lentigo maligna presents as a flat, irregularly shaped dark brown to black macule on the sun-damaged area of the face or scalp. Its margins are often ill defined. 5 Clinically, it can be very similar to a pigmented actinic keratosis 6 or other pigmented lesions, 7 even with a dermatoscope (this specialised instrument allows the clinician to examine the magnified skin with a bright non-polarised light). Histological diagnosis remains the gold standard to establish the diagnosis.
Lentigo maligna is a melanoma in situ and should be excised entirely with a wide local excision, with margins of 9mm. 8 Multiple biopsies can miss the tumour (sampling error) and be falsely reassuring and should not be done. 9 The lesion often extends beyond the margins and a woods light can help to delineate it (see Figure 6 and 7). 5
Lentigo maligna (pre-operative)
Lentigo maligna (after Mohs’ excision)
Skin cancer
BCC/basal cell carcinoma
Basal cell carcinoma is the most common skin cancer, with increasing rates worldwide. It mostly arises in the head and neck. Its incidence rate is 76⁄100 000 cases per year in England. 10 In the UK, it is more common in the South-West of England and least common in London. 10 It is common in the elderly, especially in men. The main risk factor is sun exposure, especially during childhood, and genetic predisposition. Other risk factors include fair skin, signs of actinic damage, arsenic exposure, and immunosuppression (following organ transplantation for example). 11 It is slow growing and locally invasive. Metastasis is extremely rare. 12
Classically, it presents as an elevated tumour with a pearly edges and telangiectasia. It may be pigmented, at times with a violet tinge, or take the colour of the surrounding skin. It does not have a precursor lesion. The different subtypes of BCC have different appearances, growth rates and growth patterns. The main ones in the head and neck include the following: 13
– Nodular, which has the most classical appearance. It is well-defined and often violet with raised, rolled pearly edges.
– Cystic, which are dome-shaped nodules and blue-grey in colour.
– Infiltrative, which are ill defined and growing under the skin.
– Morphoeic (or cicatricial), which are the most aggressive subtype. They appear like a scar or sclerotic plaque.
A multi-disciplinary team (MDT) involving a surgeon, a dermatologist, a pathologist and other specialists, leads the treatment plan. The mainstay treatment is surgery (often wide-local excision, or Mohs micrographic surgery for cases that are aggressive, located in key aesthetic areas, or have indistinct margins). Reconstruction of the defect is often done with a local skin flap or skin graft. Cryosurgery or curettage and cautery are also used for certain tumours. 12 Recurrence rates are low, but synchronous (which arise at a distance from the first tumour and are diagnosed simultaneously) or metachronous tumours (which arise later) are common. 11 This reflects the field cancerisation of the skin, see Figures 8 and 9.
BCC
BCC
Cutaneous squamous cell carcinoma SCC
It originates from epidermal keratinocytes or adnexal structures, 14 and is the second most common type of skin cancer. 14 The incidence rate is 22⁄100 000 cases per year in England. 10 In the UK, it is more common in the South-West and least common in London. In the head and neck, the main risk factor is chronic sun exposure and immunosuppression. It shares many of the risk factors of BCC. Some SCCs are associated with HPV(15). Bowen’s disease (SCC in situ), actinic keratosis, and actinic cheilitis (an atrophic white plaque usually originating from the lower lip) can develop into infiltrative SCC when they become fissured, eroded or ulcerated.
The clinical presentation of SCC is variable and depends on the location and subtype. 15 Clinically, they are indurated, nodular, keratinised or crusted tumours, and at times ulcerated. They may also present as an ulcer without keratinization. Clinical suspicion is confirmed with histological diagnosis. SCCs arising near the lip or ear have the worst prognosis. 10 Cutaneous SCCs of the head and neck metastasize first to the parotid, facial and cervical lymph nodes, but this is rare (around 1%). 15
These tumours are treated by a multidisciplinary team (MDT). Depending of the stage of the tumour, treatment is either with curative or palliative intent. In the UK, most patients with a head and neck cutaneous SCC present early and surgical excision of the primary is the mainstay treatment (excision with margin, MOHS or curettage and cautery for small ones, followed by reconstruction). 14 Radiotherapy can also be considered for some large tumours in certain locations, 6 especially in the elderly. Survival rates for early stage tumours are excellent (>90% overall 5 year survival). For patients with lymph node metastasis it is considerably worse (it is estimated 25-45%).
Lentigo maligna melanoma
This is the third most common skin cancer and the most lethal. It is slightly more common in females. Malignant melanoma incidence is 10-15/100 000 cases per year in Europe. 16 It is a malignant tumour of the melanocytes. Sun exposure is again the main risk factor. Lentigo malignant melanoma is the most common form of melanoma in the face and often arises from lentigo maligna. Certain changes in a mole or any pigmented lesion raises the suspicion of melanoma (see Box 1).
Suspicious changes of a mole should lead to an urgent referral to a specialist
Increase in size
Change in shape
Asymmetry
Change in colour
Inflammation of the edges
Crusting
Bleeding
Itching
Diagnosis is confirmed histologically. It can be difficult to differentiate an LMM from a normal pigmented lesion. For patients with many moles, the single lesion that looks different from the others should be treated with the utmost suspicion (ugly duckling sign). Melanomas are locally aggressive and metastasize to the regional lymph nodes, lungs, liver, bones, brain and abdomen.
Management of the melanoma patient must be in a local MDT or specialist melanoma MDT. 9 The aim of the treatment is either curative or palliative. In the early stages, wide local excision with margins of 1-3 centimetres is necessary. Regular follow up is necessary. In the early stages, the 5 year survival rate is excellent (around 97%). In the later stages, it is much worse (around 15-20%) (see Figure 10).
Cutaneous SCC of the pinna
Genetic conditions
Gorlin-Gotz syndrome
Nevoid basal cell carcinoma syndrome (NBCCS), Gorlin-Goltz syndrome, is a rare multisystem, autosomal dominant inherited condition (with variable expressivity). It presents as a spectrum of developmental anomalies. 17 To the dental practitioner, these patients will present with cysts in the maxilla or mandible and multiple BCCs. Clinically, it manifests with multiple basal cell carcinomas (with the first ones occurring as early as at 20 years old), multiple odontogenic keratocysts, palmar or plantar pits, cleft lip or palate, frontal bossing, coarse face, hypertelorism, syndactyly of the digits, calcification of falx cerebri and abnormalities of the ribs.
Neurofibromatosis
Neurofibromatosis (NF) is an autosomal dominant condition with a prevalence of 1/4000 (for neurofibromatosis type 1) and 1/200 000 (for Neurofibromatosis type 2). It finds its aetiology in the mutation of a specific tumour suppressor gene (producing neurofibromin for NF1 and merlin, schwannomin for NF2). 18 It is associated with tumours of the peripheral and central nervous system. NF1 is characteristically associated with multiple neurofibromas, whilst NF2 is associated with bilateral vestibular schwannomas. Neurofibromatosis 1 is associated with characteristic lesions of the skin; café au lait patches (hyperpigmented flat lesions), cutaneous neurofibromas (sessile or pedunculated papules, fleshy and non-tender), and axillary freckling. Looking carefully at the iris, Lisch nodules (small red hamartoma) might be evident. Neurofibromatosis 2 is associated with cutaneous schwannomas (subdermal nodule).
Tuberous sclerosis
The frequency is between 1/6000 and 1/10 000. 17 Tuberous sclerosis is associated with benign tumours in the skin, brain, kidneys, lung and heart that lead to organ dysfunction. 19 They are linked with mutations of two genes: TSC1 and TSC2. The disease develops over the lifetime and its presentation is highly variable from one individual to another (even if they are closely related). Clinically, patients with tuberous sclerosis can have hypomelanotic papules and angiofibromas. Of relevance for dentists is the association of dental enamel pits with tuberous sclerosis. Diagnosis includes genetic testing.
Referral pathway for suspected cutaneous malignancy
For patients with a suspected skin cancer (melanoma, squamous cell carcinoma, basal cell carcinomas at high risk site), advise they are seen urgently by their GP for consideration of referral to dermatology for two week wait referral (2WW). As most oral and maxillofacial surgical units in UK also treat skin cancer, an alternative for potential cutaneous malignancies in the head and neck is referral to the OMFS team, but check local guidelines and local expertise.
Summary
Dental healthcare professionals are well placed to identify common skin lesions. Patient are seen on a regular basis for review and new lesions or changes in a lesion may be spotted. Knowledge of the patient’s medical history, risk factors for cutaneous malignancies, e.g. outdoor hobbies and sunny holidays, help highlight a high-risk lesion. Recognition of potentially malignant and premalignant lesions of the skin allows timely appropriate referral for further investigation and treatment. Dental healthcare professionals who identify worrying lesions should refer to the patient’s general medical practitioner, or to a local oral and maxillofacial team. Early diagnosis leads to improved prognosis and reduced morbidity along with better aesthetic reconstructions.