What is melanoma?
Melanoma is a cancer of melanin producing cells and can therefore arise in skin, mucosa, retina and the leptomeninges.
Describe the etiologic factors for malignant melanoma. [TU 2059]
Etiology of melanoma?
- UV exposure is the major causal factor for developing MM. Cumulative exposure favours the development of lentigo maligna melanoma (LMM), whereas ‘flash fry’ exposure – typical of rapidly acquired holiday tans – favours the other morphological variants.
- Preexisting benign nevi: About 90% of malignant melanoma arises from preexisting pigmented nevus.
- A small proportion of MMs are genetically mediated, as in xeroderma pigmentosum which increases the relative risk of developing MM to 1000. Immunosuppression secondary to drugs or HIV infection will increase the incidence of MM by 20–30-fold.
Inherited conditions associated with cutaneous malignancy?
- Xeroderma pigmentosum
- Basal cell nevus syndrome (Grolin’s syndrome)
Phases of growth of melanoma?
1. A radial or horizontal phase of growth: The melanoma grows in the epidermis. During this phase of growth the melanoma does not invade the blood vessels or the lymphatic vessels.
2. A vertical phase of growth: During this phase of growth, the melanoma invades the dermis and the deeper tissues. During this phase of growth, the melanoma invades the blood vessel or the lymphatic channels and may lead to metastasis.
Features of melanoma?
- Asymmetrical skin lesion.
- Border of the lesion is irregular.
- Color: melanomas usually have multiple colors.
- Diameter: moles greater than 6 mm are more likely to be melanomas than smaller moles.
- Enlarging: Enlarging or evolving.
TNM staging of melanoma - AJCC eighth edition
- •T1 – ≤1 mm
- - T1a <0.8 mm without ulceration
- - T1b <0.8 mm with ulceration or 0.8 to 1 without ulceration
- •T2 – >1 to 2 mm
- - T2a - absence of ulceration
- - T2b - presence of ulceration.
- •T3 – >2 to 4 mm
- - T3a - absence of ulceration
- - T3b - presence of ulceration.
- •T4 – >4 mm
- - T4a - absence of ulceration
- - T4b - presence of ulceration.
- N1 - 1 node
- N2 - 2-3 nodes
- N3 - 4 or more nodes
- M1a Distant skin, subcutaneous, or nodal metastases
- M1b Lung metastases
- M1c All other visceral metastases
Clinical types of malignant melanoma?
- 1. Superficial spreading: Most common
- 2. Nodular melanoma: worst prognosis after amelanotic type.
- 3. Lentigo maligna melanoma: Less common, least malignant. Occurs in old age and is common in face. Also known as Hutchinson’s melanotic freckle.
- 4. Acral lentiginous melanoma: It affects the soles of the feet and the palms of the hands.It has got a poor prognosis. It is least common. It mimics fungal infection/pyogenic granuloma.
- 5. Amelanotic melanoma: This is the worst type.
- 6. Desmoplastic melanoma.
[@ AA LeDe SuNo]
Describe Breslow's staging and Clarke's level of invasion in malignant melanoma and their importance in surgical management. [TU 2062/1]
Enlist etiological factors of malignant melanoma. Describe the Clarke-Mc Govern classification of malignant melanoma. [TU 2057]
Describe Breslow’s staging and clark level of invasion of malignant melanoma and their importance in surgical management. [TU 2062]
Breslow's depth was used as a prognostic factor in melanoma of the skin. It is a description of how deeply tumor cells have invaded. Currently, the standard Breslow's depth has been replaced by the AJCC depth. Originally, Breslow's depth was divided into 5 stages.
- Stage // Depth
- Stage I // less or equal to 0.75mm
- Stage II // 0.76 mm - 1.50mm
- Stage III // 1.51 mm - 2.25mm
- Stage IV // 2.26 mm - 3.0mm
- Stage V // greater than 3.0 mm
Describe the Clark-McGovern classification of malignant melanoma. [TU 2059]
Clark's level is a related staging system, used in conjunction with Breslow's depth, which describes the level of anatomical invasion of the melanoma in the skin. Clark's level was the primary factor in earlier AJCC staging schemae for melanoma. However, with further study, it has been shown that Clark's level has a lower predictive value, is less reproducible, and is more operator-dependent as compared with Breslow's depth. Thus, in the current (2010) AJCC staging system, Clark's level has prognostic significance only in patients with very thin (Breslow depth <1 mm) melanomas.
Five anatomical levels are recognized, and higher levels have worsening prognostic implications. These levels are:
- Level 1 : Melanoma confined to the epidermis (melanoma in situ)
- Level 2 : Invasion into the papillary dermis
- Level 3 : Invasion to the junction of the papillary and reticular dermis
- Level 4 : Invasion into the reticular dermis
- Level 5 : Invasion into the subcutaneous fat
Treatment of Melanoma?
An excisional biopsy with a 1 to 2 mm rim of normal-appearing skin should be used for lesions suspected to be a melanoma. The malignant melanoma does not usually invade the deep fascia and so excision of the deep fascia is not required in most cases.
- Once a diagnosis of melanoma has been established, surgical excision with an adequate margin of normal tissue is required.
- - In situ melanoma - 0.5 cm margin of normal tissue
- - T1 - 1 cm margin of normal tissue
- - T2,T3,T4 - 2 cm margin of normal tissue
- If anatomic considerations preclude an adequate resection margin or if the lesion is considered to be at particularly high risk of local recurrence (desmoplastic melanoma) - adjuvant radiation therapy (RT) postoperatively
- Lymphatic mapping and sentinel lymph node biopsy are indicated in the initial management of all melanomas except T1a lesions.
Features of Basal cell carcinomas?
- It is usually a slow growing, locally invasive malignant tumour of pluripotential epithelial cells arising from basal epidermis and hair follicles, hence affecting the pilosebaceous skin.
- Risk factors -
- - The strongest predisposing factor to BCC is ultraviolet radiation.
- - Other predisposing factors include exposure to arsenical compounds, coal tar, aromatic hydrocarbons, ionising radiation and genetic skin cancer syndromes.
- - It occurs in the middle aged or elderly with 90 per cent of lesions found on the face above a line from the lobe of the ear to the corner of the mouth.
- - Usually starts as a small pimple that ulcerates and has raised edges (‘rodent ulcer’).
Microscopic feature of BCC?
- The characteristic finding is of ovoid cells in nests with a single ‘palisading’ layer. It is only the outer layer of cells that actively divide. This may explain why tumour growth rates are slower than the cell
- cycle speed would suggest, and why incompletely excised lesions are more aggressive.
Treatment of BCC?
- It is easily excised in the early stages.
- Histological confirmation that the excision is complete is required.
- More extensive lesions may require specialist techniques, such as Mohs’ micrographic surgical excision controlled by frozen section.
- Local radiotherapy or cryotherapy can be carried
- out; however, recurrence is more common, more aggressive and more difficult to detect.
What is Marjolin’s ulcer?
- Marjolin’s ulcer is a low grade squamous cell carcinoma, which develops on a chronic benign ulcer or a long standing scar tissue.
- Marjolin’s ulcer may develop in Postburn scar, Long standing venous ulcer or Chronically discharging osteomyelitic sinus