The histology of melanomas is very variable depending on the specific subtype and primary site. Many of the features assessed by histology have prognostic value (Box 14.1). In addition to these the pathologist should report the type of melanoma, greatest thickness, radial or vertical growth phase, excision margins and immunohistochemical stains. Immunohistochemical stains used in melanoma include S100 (the most frequently used but also stains benign melanocytes), HMB-45, Mitf, MART-1 and tyrosinase.

Presentation

Patients usually present with new skin lesions or change in existing skin lesion. It is important to get a detailed history of:

• How long lesion has been present?

• When did it start changing?

• Whether it arose from a pre-existing lesion?

• Previous history of sun exposure, sun burns, skin cancers and immunosuppressive treatment.

• Family history of melanoma.

Initial assessment

Initial assessment of patients with suspected melanoma includes detailed examination and a clinical photograph of the lesion, full skin examination and examination for lymphadenopathy and hepatomegaly. Clinical signs of melanoma include itching, bleeding, ulceration or changes in a pre-existing mole. ABCDE features (Figure 14.1) help to distinguish early melanoma from a benign mole:

• A – Asymmetry.

• B – Border irregularity.

• C – Colour variation.

• D – Diameter of >6 mm.

• E – Evolution (change in lesion).

Figure 14.1 Early melanoma showing ABCD signs (A) and advanced plaque like melanoma (B) with nodule which also exhibits ABCD signs.

From Darrell Rigel: Cancer of the Skin (Saunders) with permission.

Investigations

In the absence of clinical evidence of metastatic disease in regional lymph nodes at presentation, there is no indication for any staging investigations. In patients with thick primary tumours (>4 mm), CT scan may be useful prior to rule out metastatic disease. Studies show that a routine chest X-ray revealed metastasis in only 0.1% whereas 15% showed false positivity. Similarly CT scan showed metastasis in 1.3% while false positivity was 16%.

Patients with >4 mm thick lesion and evidence of nodal metastasis (including micrometastasis) need staging investigations with full blood count, liver function tests, serum lactate dehydrogenase (LDH), chest X-ray and CT scan of chest, abdomen and pelvis.

Tissue diagnosis

Excision biopsy to include 2–5 mm of clinical margin of normal skin with a cuff of subdermal fat is the standard procedure. This helps to confirm diagnosis and provide guidance for subsequent management based on Breslow thickness. Full thickness incisional biopsy from the thickest part of the lesion is acceptable as a mode of diagnosis in certain anatomical areas (e.g. face, ear, palm/sole) and for large lesions. Shave and punch biopsies are not recommended.

Staging

Breslow thickness, ulceration and mitotic count are most important prognostic factors of localized disease whereas Clark level is an independent prognostic factor for melanoma of <1 mm thickness (Box 14.1). Staging is by TNM AJCC system and is related to prognosis (Table 14.1). M1a includes distant skin, subcutaneous or nodal metastases with a normal LDH. M1b is lung metastases with a normal LDH and M1c is with any other metastases or with a raised LDH level.

Table 14.1 TNM staging & 5-year survival of cutaneous melanoma

Staging	5-year survival (%)
Stage IA	95
T1aN0M0 ≤1 mm thickness without ulceration and mitosis <1/mm²
Stage IB	91
T1bN0M0 ≤1 mm thickness with ulceration or mitosis ≥1/mm²
T2aN0M0 1.01–2 mm thickness without ulceration
Stage IIA	77–79
T2bN0M0 1.01–2 mm thickness with ulceration
T3aN0M0 2.01–4 mm thickness without ulceration
Stage IIB	63–67
T3bN0M0 2.01–4 mm thickness with ulceration
T4aN0M0 >4 mm thickness without ulceration
Stage IIC	45
T4bN0M0 >4 mm thickness with ulceration
Stage IIIA
T1-4aN1aM0 Micrometastasis* in 1 node	70
T1-4aN2aM0 Micrometastasis in 2–3 nodes	63
Stage IIIB
T1-4bN1a/2aM0	50–53
T1-4aN1bM0 Macrometastasis** in 1 node	46–59
T1-4aN2bM0 Macrometastasis in 2–3 nodes	46–59
T1-4aN2cM0 in-transit metastases/satellites without nodes
Stage IIIC	24–29
T1-4bN1b/2b/2cM0
Any T N3M0 metastasis in >3 nodes or matted nodes or in-transit or satellites with metastatic nodes
Stage IV
Any T, any N, M1 distant metastasis	7–19%

*micrometastases after sentinel node biopsy; **macrometastases are clinically detectable pathologically confirmed nodes.

Management

Non-metastatic disease

Agent	% Response rate (CR + PR)
Dacarbazine	20
Temozolamide	21
Carmustine (BCNU)	18
Lomustine (CCNU)	13
Cisplatin	23
Carboplatin	16
Vinblastine	13
Paclitaxel	18
Docetaxel	15

Immunotherapy with high dose interleukin-2 (IL-2) or interferon alpha has shown response rates of 10–21%. Toxicities include hypotension, capillary leak syndrome, sepsis and renal failure.

A recent study of ipilimumab, a monoclonal antibody against cytotoxic T-lymphocyte antigen 4 (CTLA-4), showed improved overall survival in previously treated patients with unresectable stage III/IV melanoma who were positive for HLA-A*0201. Side effects of this treatment included rash, colitis, diarrhoea and hepatitis.

Combining chemotherapy with an immune modulator has been assessed in several clinical trials. A meta-analysis showed that this improved response rates, but did not translate into a survival benefit.

In summary no drug or combination of drugs has shown a significant response rate and survival benefit over single agent dacarbazine. It remains the standard drug in metastatic melanoma but patients should be entered into clinical trials where possible.

Isolated limb perfusion

In some cases widespread metastases do not occur but there may be disseminated skin metastases in a limb which cover an area too large for radiotherapy. In these patients, if systemic treatment is not feasible, isolated limb perfusion with TNF-alpha and melphalan can establish good local control. This is only performed in a limited number of centres but can provide good clinical benefit.

Radiofrequency ablation

For some patients with limited systemic disease but in whom surgery is not possible, radiofrequency ablation (RFA) has been used for liver and lung metastases. In general they should be less than 5 cm in size and accessible to the RFA catheter used. Complications include bleeding and pneumothorax.

Newer agents

Given the risk of recurrence and poor outcomes with systemic treatment in metastatic disease, new agents are being developed to target specific pathways involved in melanoma. Examples include VEGF, BRAF and bcl-2. Studies are ongoing to assess the potential benefit of bevacizumab in resected stage III and stage IV disease and the role of other anti angiogenics. Sorafenib which is a TKI which has activity against BRAF has been shown to improve response rates when combined with chemotherapy, although no survival benefit was observed. Agents with a more specific BRAF activity are being developed.

Prognostic factors and survival

Prognostic factors are highlighted in Box 14.1. Survival according to stage is included in Table 14.1.

Follow-up

After surgery all patients should be followed up due to the risk of further melanomas as well as nodal or systemic recurrence. Full skin and nodal examination should be carried out and abdominal examination to exclude hepatomegaly. For high-risk patients (>IA) blood tests to examine LDH, liver function tests and FBC may be carried out. At the point of nodal recurrence reassessment with CT is suggested prior to surgery and 6–12 months later. For those who have had metastatic disease resected a CT several months later is recommended along with close follow-up. All patients, especially who have had nodal disease or metastases, should be warned about the symptoms of spinal cord compression.

Non-cutaneous melanoma

Ocular melanoma

Ocular melanoma is a rare subtype of melanoma which can occur in many areas of the eye. Most commonly it occurs in the choroid but less than 5% occur in the iris. The aetiology is uncertain; some studies suggest a link with UV radiation. The risks are higher in those who have had cutaneous melanoma, pale iris colour or who have a family history of ocular melanoma. The staging system differs to that of cutaneous melanoma.

Poor prognostic factors include age over 60, size and involvement of the ciliary body. Although often localized at presentation they have a high risk (10–80% depending on number of prognostic factors) to spread to the liver, often several years after successful treatment of the primary. Long-term survival is less than 35% even with successful treatment of the primary. Surgery used to be the standard treatment but radiotherapy has replaced this in most cases. Radiotherapy can be administered as external beam, as a radio-active plaque (e.g. iridium-192) or with protons or other charged particles. Local control rates are similar with each technique. The vision is often lost in the irradiated eye with the list of complications including cataracts, glaucoma, retinopathy and vitreous haemorrhage.

Treatment of metastases in ocular melanoma has shown that they tend to have a reduced response rate to chemotherapy and immunotherapy than cutaneous melanoma and are more rapidly progressive.

Due to their propensity for metastases (especially liver and lung) which can be delayed, follow-up includes imaging of the liver and lungs in addition to LDH and liver function tests. Combined follow-up with ophthalmology is required.

Mucosal melanoma

Mucosal melanomas constitute less than 2% of all melanomas. The most common sites of presentation are head and neck (up to 50%), female genital tract (25%) and anorectal (20%). The remainder occur in very rare sites such as other areas of the gastrointestinal tract, Eustachian tube and salivary glands. They occur later in life (50–70s) than cutaneous melanoma, are more common in non-Caucasians and slightly more common in men than women. They tend to present late as they are essentially hidden from sight and have a very poor prognosis. For head and neck tumours 5-year survival is less than 30% which reduces to <20% with involved lymph nodes. The most common presentation is with bleeding, anaemia or local symptoms such as pain. There is no specific staging system. The treatment of choice is surgical resection with clear margins but this is often difficult due to location of the tumour. Radiotherapy has been used to try to improve local control but has not shown an improvement in survival and is not a standard practice. A study using carbon ions to minimise local morbidity showed good local control but 5-year survival was still less than 30%. Chemotherapy with standard drugs for cutaneous melanoma has been tried with similar success. Nodal disease occurs to a greater extent than in ocular melanoma so regional lymph nodes should always be examined at follow-up.

Basal cell carcinoma

Introduction

Basal cell carcinoma (BCC) is a slow growing, locally invasive (hence called rodent ulcer) malignant epidermal skin tumour. The exact incidence is difficult to obtain; though there is a worldwide trend in increasing incidence.

The most significant aetiological factors appear to UV exposure and genetic predisposition. BCC is common in the sun-exposed area of head and neck. Multiple BCC is a feature of Gorlin’s syndrome. Other risk factors include increasing age, male, fair skin, immunosuppression, vaccination scars and arsenic exposure. Sunscreen use and low fat diet are thought to be protective.

Pathology

The common histologic subtypes are superficial, nodular and morphoeic (sclerosing). Other variants include micronodular, infiltrative and basosquamous BCC which are aggressive with high local recurrence. Perivascular and perineural invasion is associated with aggressive tumours. BCC infiltrate tissues in a three dimensional fashion. Lymph node metastasis is extremely rare except in those with multiple recurrences or uncontrolled primary tumour.

Clinical features

The common growth patterns are superficial, multifocal, nodular and morphoeic (Figure 14.2). The sites affected are head and neck (52%), trunk (27%), upper limb (13%) and lower limb (8%).

• Superficial BCC occurs on the trunk or limbs of young people. It presents as a well-defined, erythematous, scaling or slightly shiny macular lesion. Stretching the lesion causes an increase in the degree of erythema, highlights the shiny surface and reveals a peripheral thread-like pearly rim or island of pearliness distributed throughout the lesion. These lesions will progressively enlarge and may reach 5–10 cm in diameter. Biopsy is needed prior to definitive treatment.

• Nodular BCC occurs on the head and neck region of elderly patients. It presents as a shiny, pearly, telangiectatic papule or nodule. The pearly appearance becomes more obvious during skin stretching. Radially arranged dilated capillaries are often seen across the surface of lesion. With ongoing growth, tumour ulceration can occur which leads to central umbilication of lesion with a raised rolled border. Islands of pigments can also be seen.

• Morphoeic SCC typically presents as a pale scar and palpation reveals firm induration which extends more widely and deeply than is evident on inspection. It slowly enlarges to reach a large size. Biopsy is necessary.

Figure 14.2 Nodular BCC with rolled borders with telangiectasia (A) and a morphoeic BCC characterized by a white plaque with telangiectasia and ill-defined borders (B).

From Darrell Rigel: Cancer of the Skin (Saunders) with permission.

Other histolological subtypes are uncommon and do not have any characteristic clinical presentation.

Examination

Clinical examination should be done in a well-lit area with the aid of a magnifier. Whole skin examination and regional nodal examination is necessary.

Diagnosis

Diagnosis is often clinical. Biopsy is indicated when there is clinical suspicion of an alternative diagnosis or histologic subtype may influence treatment decision. Punch or shave biopsy may be appropriate. Imaging of the local area, e.g. by CT, may be indicated when there is suspicion of bone involvement and deep infiltration (particularly for a lesion close to the embryonic fusion lines such as the nasal vestibular region, or pre- and post-auricular regions).

Treatment

Treatment is aimed at eradication of tumour with acceptable cosmetic and functional outcome. A number of treatment options are available (Box 14.2) and the choice of treatment in small BCC depends on various factors (Box 14.3). Radiotherapy is indicated when cosmetic and/or functional outcome is better with radiotherapy compared with surgery and when there is a need to avoid complex plastic surgery.

Box 14.3
Treatment of choice in BCC

Surgery and radiotherapy (RT) are effective treatment for small and less invasive tumours. Large and deeply invasive lesions are treated with surgery with or without postoperative radiotherapy.

RT favoured in:

• Mid-face, nasal, inner canthus, lower eye lid, lip commissures (better function)

• Multiple superficial lesions difficult to excise (better cosmesis)

• Patients >70 years (long-term toxicity is less of an issue)

• Patients who wish to avoid surgery

• Patients prone to keloid formation

Surgery is the choice in:

• Readily excisable lesions in those <70 years

• Lesions in hair-bearing areas or overlying lacrimal gland

• Recurrence after radiotherapy

• Multifocal disease especially with dysplastic skin

• Upper eyelid tumours (better function)

• Dorsum of the hand (better function)

• Below knee and other sites of poor vascularity (problem with healing and function)

• Invasion to bones and joints *

^* Cartilage invasion is not an absolute contraindication to radiotherapy. Radiotherapy is, however, avoided in large pinna lesions with extensive, inflamed or painful cartilage invasion.

Surgery

Wide excision (WE)

WE of simple lesions need a 2–3 mm margin whereas complex lesions or clinically poorly defined lesions need a margin of 3–5 mm. An adequate microscopic margin is 0.5 mm. The most appropriate management after incomplete excision is debatable. The treatment options include re-excision, radiotherapy or observation. Adjuvant radiotherapy improves 5-year survival from 61 to 91%. Observation is an option for elderly patients where further surgery and radiotherapy may not be appropriate.

Mohs’ micrographic surgery

During this procedure, the tumour is excised and the entire peripheral and deep margins are examined by frozen section for residual tumour. Mapping and staining of excised tissue and a specialized tissue sectioning procedure enables precise localization of residual tumour and the process of excision continues until the margin is tumour free. This is more appropriate for tumours with poorly defined borders, recurrent tumour and extensive disease.

Radiotherapy

Radiotherapy results in 93–95% 10-year control rate for BCC of ≤2 cm. Radiotherapy details are given in Box 14.4.

Box 14.4
Radiotherapy for skin cancer

Consent

• Acute reactions involve dermatitis and mucositis which resolve by 6 weeks following treatment.

• Late effects involve thinning of skin, alopecia, loss of sweating, change in colour, telangiectasis and fibrosis.

Position and immobilization

Depends on the site.

Treatment volume

• Well-defined BCC – 5 mm margin around macroscopic tumour.

• Ill-defined BCC and SCC – 10 mm margin.

Beam shaping – custom made lead cut out for X-rays and end frame cut-out for electron. Crenallation of the margin of a round cut out gives a better cosmesis by blurring the edge of radiation reaction.

Radiotherapy dose

BCC is thought to be more radiosensitive than SCC. Equivalent doses for BCC and SCC and rough guide for selection of fractionation regime are as follows:

BCC	SCC
60 Gy/30 fractions/6 weeks*	60–66 Gy/30–32 fractions
50 Gy/20 fractions/4 weeks*	55 Gy/20 fractions
40 Gy/15 fractions/3 weeks	40 Gy/10 fractions
40.5 Gy/9 fractions/3 weeks	45 Gy/9 fractions
32.5 Gy/5 fractions/1 week	32.5 Gy/5 fractions
32 Gy/4 fractions/4 weeks**	32 Gy/4 fractions/4weeks
12–15 Gy/1 fraction**	12–15 Gy/1 fraction

Special considerations

Electron planning

• Electron beam field is defined by 50% isodose and the 90% isodose is 3–5 mm inside the field. Hence, in order to enclose the PTV within 90% isodose, a 5 mm larger electron applicator than defined by PTV is needed.

• At higher energies, isodoses close to the surface bows inwards which necessitates 1 cm larger applicator diameter than the defined PTV to ensure homogenous dose to the tumour (p. 18, Figure 3.2B).

• Surface dose increases with electron energy; a bolus is needed for lower energies to bring up 90% isodose to the skin surface (p. 18, Figure 3.2A).

• Bolus is also used to bring up high dose to surface to avoid radiation to underlying critical structures.

• Stand off effect – fill the area with bolus/calculate correction

Normal tissue shielding

• Lower eyelid and canthi tumours need corneal shielding.

• Lip tumours need buccal shields. Shields should be coated with wax to absorb scattered radiation.

• Tumours in the pinna and nasal regions when treated with electrons need wax coated lead plugs in the external auditory canal and nose respectively to avoid normal tissue damage.

^* fractionation used in patient aged <70 years and/or tumour of >3–4 cm;

^** used in frail patients.

Recurrence

Recurrence is common with mid face and pre-auricular lesions, tumours >2 cm and aggressive subtypes. Two-thirds of recurrences occur within 2 years of primary treatment and 20% occur in 2–5 years. Recurrences after non-surgical treatment are generally treated with surgical resection followed by plastic surgical repair. Recurrence after surgical treatment can be treated with surgery or radiotherapy.

Prognosis

Overall 10-year control rate is >90%. A number of factors influence prognosis. The important prognostic factors are size, depth of invasion, histological subtype (morphoeic, infiltrative and basosquamous have higher recurrence), completion of excision (incomplete excisions have a 30% recurrence rate), site of disease (disease around nose, eyes and ears have higher recurrence rates) and presence of perineural spread.

Squamous cell carcinoma

Introduction

Squamous cell carcinoma (SCC) is the second most common skin cancer constituting 20% of skin malignancies. The incidence appears to be increasing and males are more commonly affected.

Risk factors include exposure to ionizing or ultraviolet radiation, immunosuppression, scars, chronic wounds, smoking and arsenic exposure. Congenital conditions such as oculocutaneous albinism and xeroderma pigmentosum are also associated with increased risk of SCC. It is common in sun-exposed areas and hence sun screen is protective.

Pathology

In situ (Bowen’s disease) SCC is limited to epidermis which presents as a flat scaling pink lesion with irregular borders. There is no risk of metastasis, although progression to invasive SCC occurs in 3–11% of cases.

In situ SCC of the glans penis (erythroplasia of Queyrat) has 20% risk of metastasis and 30% can progress to invasive disease.

Invasive SCC is composed of a collection of atypical keratocytes which invade the dermis and deeper structures. Other histologic variants are:

• Adenoid SCC – can metastasize in 3–19% and associated with rapid local growth.

• Adenosquamous SCC – shows squamous appearance superficially and glandular appearance deeply. These are aggressive tumours.

• Spindle cell SCC – appears as ulcerated nodules or exophytic tumours and may be difficult to distinguish from sarcoma histologically. These tumours are aggressive with a tendency to perineural invasion and metastasis (25%).

• Verrucous SCC – appears like a large wart. These are slow growing, locally invasive and do not metastasize.

• Keratoacanthoma – appears as a rapidly growing nodule with a central keratin plug. True lesions can undergo spontaneous regression but most are now viewed as SCC.

Clinical presentation

Typical presentation is a raised pink papule or plaque with erosion or ulceration (Figure 14.3). In advanced cases it presents as large ulcerated masses and bleeding. Metastasis is primarily to the regional nodes (2–6%). The head and neck region is the commonest site in men whereas the upper limb followed by head and neck are the commonest sites in females. Only 8% of SCC arise on the trunk.

Figure 14.3 Digital squamous cell carcinoma.

From Darrell Rigel: Cancer of the Skin (Saunders) with permission.

Examination

Examination should be of the whole skin and regional lymph nodes.

Diagnosis

Tissue biopsy is essential for diagnosis. CT scan helps to detect regional lymph nodes. FNA of the enlarged lymph node under radiological guidance is advised. Open surgical biopsy should be avoided. The role of sentinel node biopsy is evolving.

Staging

T1 – ≤2 cm in greatest dimension.

T2 – >2 to 5 cm in greatest dimension.

T3 – >5 cm in greatest dimension.

T4 – tumour invades deep extradermal structures.

N1 – regional nodal metastasis.

M1 – distant metastasis.

Treatment

Three factors that influence treatment of SCC are: the need for removal of tumour locally, the possibility of ‘in-transit’ metastasis and regional nodal metastasis. Treatment options include:

• Cryotherapy (for small tumours with well defined borders).

• Curettage and electrodessication (for well differentiated tumours of <1 cm size).

• Radiotherapy (see Box 14.3) – used as a primary treatment and adjuvant after surgery.

• Surgical excision (see Box 14.3) and Mohs’ micrographic surgery.

Surgery

Surgery is aimed at complete removal of the tumour and of any metastasis. Low-risk tumours of <2 cm are excised with a minimal margin of 4 mm whereas tumours of >2 cm size, high risk tumours (grade 2–4, in high risk locations such as ear, lip, scalp, eyelids and nose) and those extending into subcutaneous tissue need a minimum margin of 6 mm or more. Depth of excision should be through normal underlying fat. The accepted minimal microscopic margin is >1 mm.

Mohs’ micrographic surgery is indicated in high risk tumours and recurrences.

Management of lymph nodes

The treatment of metastatic lymph nodes is primary surgery. Elective lymph node dissection is not routinely advised. There is some evidence that it may have a role in tumours of >8 mm in depth. Patients with recurrent thick (>4 mm) lesions in the vicinity of the parotid (temple, forehead and preauricular area) may also be considered for elective nodal treatment.

Radiotherapy

Principles of primary radiotherapy and treatment guidelines are same as that of BCC (Boxes 14.3 and 14.4). 5-year control rate with radiotherapy is comparable with surgery with >93% for T1 lesions, 65–85% with T2 and 50–60% with T3–4 lesions. Radiotherapy is indicated after incomplete excision when further surgery is not contemplated, as incomplete excision leads to 50% local recurrence.

Postoperative radiotherapy to the primary tumour site is considered for patients with high risk disease after complete excision. High risk disease includes: tumour invasion beyond subcutaneous tissue (T4), recurrent disease, margin <5 mm, perineural invasion (major or minor nerve), lymphovascular invasion, in-transit metastases and nodal metastasis. Indications for postoperative radiotherapy after primary surgical management of metastatic lymph nodes are:

• ≥3 cm node.

• ≥2 positive nodes in neck and ≥3 nodes in axilla and groin.

• Extranodal extension.

• Close or positive margin.

• Skin involvement.

• Major nerve involvement.

• Parotid node metastases.

• After salvage surgery for recurrent nodal metastases.

The role of postoperative chemo-radiotherapy for high risk SCC is being evaluated. Palliative radiotherapy is used in metastatic disease to obtain symptom relief.

Chemotherapy

In patients with distant metastasis from SCC, cisplatin based chemotherapy is the most effective regime. A commonly used combination is cisplatin with adriamycin, which has an overall response rate of >80% with complete response rate of 30%. However, survival is generally less than 2 years.

Recurrence

Most recurrences occur within 2–3 years. Treatment is individualized based on the extent of recurrence and previous treatment.

Prognostic factors

• Grade of differentiation – grade 3–4 lesions are twice as likely to recur and three times as likely to metastasize than grade 1–2 lesions.

• Histologic type – spindle cell carcinoma and adenosquamous carcinoma have high risk of recurrence and metastasis.

• Location of tumour – scalp, lips, pinna, nose and genital lesions have a high risk of metastasis.

• Tumour size – risk of recurrence and metastasis increases with size of the tumour. Risk of recurrence is twice (15% vs. 7%) and risk of metastasis is three-fold (30% vs. 9%) in tumours >2 cm compared with tumours of <2 cm.

• Depth of invasion – tumours with depth <2 mm seldom metastasize whereas those with >4 mm have high risk of recurrence and metastasis.

• Perineural invasion – occurs in 2.5% of tumours and its presence indicates a high risk of local recurrence (up to 50%) and distant metastasis (up to 35%).

• After lymphadenectomy, prognosis depends on number of positive nodes and presence of extranodal spread.

• Recurrence – local recurrence increases rate for further recurrence (25%) and lymph node metastasis (30%).

• Tumours in immunosuppressant patients and those arising from scars have a poor prognosis.

Outcome

Local control rate for SCC is 10–15% lower than a similarly sized BCC.

Bowen’s disease (in situ SCC)

Presents as a slow-growing erythematous plaque. Surgery, topical treatment and radiotherapy are the options of treatment. Radiotherapy involves 40–50 Gy in 10–20 fractions using 100–150 kV superficial X-rays resulting in 95–100% local control.

Keratoacanthoma

Presents as a rapidly enlarging lesion with central keratin plug. Histologically, it is difficult to distinguish this from SCC. In up to 20% of patients spontaneous regression can occur over 6–12 weeks. Treatment options include early excision and radiotherapy (similar to SCC).

Squamous cell carcinoma of lip

Lesions involving <30% of lip can be treated with wedge excision and repair. When >30% of the lip is involved, surgery results in functional disability and hence radiotherapy is a treatment option. Treatment is with orthovoltage X-rays or electrons with an intraoral lead shield to protect the mandible or teeth or by implantation. Typical radiation dose is 50–55 Gy in 20–25 fractions.

Merkel cell carcinoma

Introduction

Merkel cell carcinoma (MCC) is a rare aggressive neuroendocrine tumour of the skin. The exact aetiology is not known. The reported risk factors include ultraviolet exposure, previous skin cancers and haematological malignancies, immunosuppression and HIV infection. The average age at presentation is 69 years. Males are more commonly affected.

Pathology

Histologically these are small blue cell neoplasms which express neuroendocrine and cytokeratin markers.

Clinical features

MCC present as red or violaceous nodules with a shiny surface, often with overlying telangiectasia (Figure 14.4). Spread through dermal lymphatics can result in the development of satellite lesions. The most common site of disease is the head and neck region, followed by extremities and trunk. One-third of patients have regional nodal metastases at presentation and 50% develop distant metastasis. Liver, lung, bone and brain are the sites of distant metastases.