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Skin lesions

Skin lesion case challenge

A 55-year old woman presents for a skin check. Which of the following statements indicate she is at significant risk of skin cancer? * She has skin that tans easily and burns rarely * She has a skin graft on her ankle *! Fifteen years ago, a melanoma was excised from her ankle * Her sister has had several benign moles excised Explanation: The past history of melanoma gives a lifelong increased risk of melanoma. The estimated 10-year risk for developing a second primary melanoma in a group of 5250 patients studied by the Sydney melanoma unit was 12.7% (95% confidence interval, 10.5%-14.9%). The method of repair after primary excision of the melanoma is irrelevant. Explanation: The presence and number of common acquired and dysplastic melanocytic naevi is a major constitutional risk factor for melanoma in fair-skinned people. However, we do not know this patient’s sister’s mole pattern.

The following is part of an abstract of article written by members of the New South Wales Cancer Council. *

There is persuasive evidence that each of the three main types of skin cancer, basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and melanoma, is caused by sun exposure. The incidence rate of each is higher in fairer skinned, sun-sensitive rather than darker skinned, less sun-sensitive people; risk increases with increasing ambient solar radiation; the highest densities are on the most sun exposed parts of the body and the lowest on the least exposed; and they are associated in individuals with total (mainly SCC), occupational (mainly SCC) and non-occupational or recreational sun exposure (mainly melanoma and BCC) and a history of sunburn and presence of benign sun damage in the skin.

* Armstrong BK, Kricker A. The epidemiology of UV induced skin cancer. J Photochem Photobiol B. 2001 Oct;63(1-3):8-18.

A careful examination of the patient reveals several lesions of concern. The first is on the lower leg, above the original graft site. The patient is uncertain how long it has been present, but reports that the lesion itches from time to time.

Which of the following ABCD features of melanoma are true for this lesion? #! Asymmetry # Border irregularity # Colour variation #! Diameter more than 6 mm Explanation: In this image, the most marked features are asymmetry and diameter over 6mm. Although there is slight border irregularity and colour variation, these are no more than might be observed in benign melanocytic naevi. Dermoscopic features supported a clinical diagnosis of melanoma. Is it likely to be a primary melanoma or a metastasis? *! Primary lesion * Metastatic lesion Explanation: The clinical features suggest a primary melanoma. Metastatic melanoma arises within the dermis and generally presents as a uniformly pigmented (most often blue or black) or amelanotic nodule. However rarely it may be epidermotropic and simulate a primary melanoma. This would be most unlikely to arise 15 years after initial treatment.

The lesion was excised with a 5-mm margin. This is the pathologist’s description of the histology:

In the centre of the specimen is an in situ melanoma showing elongation of the rete pegs lined by single and small nests of moderately dysplastic melanocytes. These show patchy invation of the overlying epidermis which is intact. There is underlying fibroplasia. The mitotic rate is low. There is no vascular invasion and no evidence of invasion of the underlying dermis. There is no significant inflammatory cell reaction. The entire lesion is completely excised with a margin at least 4mm.
The appearances are of an in situ superficial spreading type malignant melanoma arising in a pre-existing dysplastic naevus.
Features of in situ melanoma include: #! Melanoma that is in radial growth phase #! Intraepithelial atypical melanocytes # Biological potential to metastasise # Another name for lentigo maligna Explanation: In situ melanoma refers to early melanoma in which the melanocytes have not yet invaded the basement membrane into the dermis. Radial growth phase refers to the lateral spread of tumour cells. Lentigo maligna, superficial spreading melanoma and acral lentiginous melanoma have an in situ phase that is characterized by increased numbers of intraepithelial melanocytes, which (1) are large and atypical, (2) are arranged haphazardly at the dermal-epidermal junction, (3) show upward (pagetoid) migration, and (4) lack the biologic potential to metastasize.

On her initial visit, the dermatologist identified several other lesions. She had a 4 mm nodule on the right ala nasi.

The clinical diagnosis is: * Squamous cell carcinoma * Intradermal naevus *! Nodular basal cell carcinoma * Basal cell papilloma Explanation: The lesion is a nodular basal cell carcinoma (BCC), characterised by pearly smooth surface, dome shape, central ulceration and telangiectasia. A squamous cell carcinoma would be expected to be scaly. A skin coloured intradermal naevus may appear similar but is unlikely to ulcerate or have telangiectatic vessels. Basal cell papillomas (seborrhoeic keratoses) have a stuck-on warty appearance. Choose the most suitable treatment for this lesion from the following list: * Cryotherapy * 5-fluorouracil injections *! Excisional surgery * Phototherapy Explanation: Nodular basal cell carcinoma is generally best treated surgically. Cryotherapy can be used for basal cell carcinomas but nodular tumours have a high recurrence rate even after double freeze-thaw treatments by specialists. 5-Fluorouracil applied topically or injected into the lesion has not been found to be effective for nodular BCC. Phototherapy refers to treatment of inflammatory skin diseases with ultraviolet radiation, which may promote the growth of non-melanoma skin cancer.

The lesion on her buttock was 10mm in diameter but otherwise similar to the lesion illustrated below.

The clinical diagnosis is: * In situ squamous cell carcinoma *! Superficial basal cell carcinoma * Amelanotic melanoma * Psoriasis Explanation: This flat slowly enlarging scaly lesion is a superficial basal cell carcinoma. The bluish shiny appearance is characteristic. In situ squamous cell carcinoma may look similar, but is generally duller in hue and more keratinised. Amelanotic melanoma should always be in the differential diagnosis of growing solitary skin lesions, but a melanocytic lesion of this diameter (25mm) would be expected to have some pigmentation. Psoriatic plaques are less shiny and scalier, and rarely solitary. Which of the following treatments is / are unsuitable for superficial basal cell carcinomas? #! A two-week course of 5-fluorouracil cream # A sixteen-week course of imiquimod cream # Excision biopsy # Photodynamic therapy Explanation: 5-Fluorouracil cream is relatively ineffective in the treatment of basal cell carcinoma. A two-week course may remove about 50% of solar keratoses but would unlikely to have any effect on the lesion illustrated. The other three options are possible and have specific advantages and disadvantages.

The patient elected to receive photodynamic therapy. The lesion on the buttock was lightly scarified followed by application of methyl laevulinate in a cream base. Three hours later the treated area was exposed to 37J/cm2 light at wavelength 631 nm.

What part of the electromagnetic spectrum was used for photodynamic therapy? * Ultraviolet radiation * Blue part of visible light *! Red part of visible light * Infrared radiation Explanation: The active photosensitiser within a tumour treated with methyl laevulinate is the natural haem derivative protoporphyrin IX, which concentrates in malignant cells. This has an absorption peak within the red part of visible light is chosen, which penetrates several millimetres into the skin. A diode source of non-coherent light was used in this case, which is less expensive and has a broader beam than a laser source.

Here is the appearance of the treated area on her buttock the following day and three months later.

December 2002

March 2003

Which of the following complications are present at the three-month follow-up visit? #! Post-inflammatory hypopigmentation #! Post-inflammatory hyperpigmentation # Hypertrophic scar # Recurrent tumour Explanation: Treated lesional skin is hypopigmented and perilesional skin has developed post-inflammatory hyperpigmentation. At this stage there is no sign of recurrent basal cell carcinoma. Which circumstances predispose to post-inflammatory hyperpigmentation? #! Thermal burns #! Skin that tans easily # Skin that burns easily #! Laser resurfacing Explanation: Postinflammatory hyperpigmentation is quite common in those who tan easily or have naturally dark coloured skin following any kind of injury that affects melanocytes including trauma, inflammatory rashes, infections and destructive treatments. It slowly fades over a period of months. Postinflammatory hypopigmentation is due to a reduction or disappearance of melanocytes and is more likely to be permanent. According the Australian and New Zealand melanoma guidelines 2008, when should her next follow-up appointment be made? * One month * Three months *! Six months * Twelve months Explanation: The New Zealand guidelines state: Explanation: “It is unclear as to how long patients with melanoma should be followed up and even what the value of follow-up is”, and go on to include a table recommending follow up intervals.
Depth Follow-up intervals Length of time
in situ 3/12 1 year
<1.4 mm 3/12 then 6/12 18 mths to the 3rd anniversary
>1.4 mm 3/12 then 6/12 18 mths to the 5th anniversary
Explanation: In this patient, the most recent melanoma was in situ. The guidelines would suggest follow-up at 3-monthly intervals for a year. However, because she has had two primary melanomas and several non-melanoma skin cancers, indefinite follow-up is planned, the interval depending on the number and nature of new lesions detected.

Unfortunately, less than a year later, another small in situ melanoma, a basal cell carcinoma and an atypical naevus were excised.

Melanoma in situ left thigh

Dermoscopic view showing irregular structure