SKIN CANCER

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Malignant Skin Tumors

• Prof. N. Mbembati
• MD3 lecture

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• Most skin cancers start in the top layer of skin,
  called the epidermis. There are 3 main types of
  cells in this layer
• Squamous cells These are flat cells in the upper
  (outer) part of the epidermis, which are
  constantly shed as new ones form. When these
  cells grow out of control, they can develop into
  squamous cell skin cancer (also called squamous
  cell carcinoma).
• Basal cells These cells are in the lower part of
  the epidermis, called the basal cell layer. These
  cells constantly divide to form new cells to
  replace the squamous cells that wear off the
  skins surface. As these cells move up in the
  epidermis, they get flatter, eventually becoming
  squamous cells. Skin cancers that start in the
  basal cell layer are called basal cell skin
  cancers or basal cell carcinomas.
• Melanocytes These cells make the brown pigment
  called melanin, which gives the skin its tan or
  brown color. Melanin acts as the bodys natural
  sunscreen, protecting the deeper layers of the
  skin from some of the harmful effects of the sun.
  Melanoma skin cancer starts in these cells.

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Basal cell carcinoma

• Slow growing tumour from basal epithelium of the
  skin.
• U/V light exposure main risk factor but also
  arsenic compounds, coal tar, ionizing radiation
• Occurs more in the tropics
• Tumour of the middle age and the elderly.
• 90 of tumours occur on the face above the line
  from corner of the mouth to lobe of the ear.

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Basal Cell carcinoma

• 90 are nodular or nodular/cystic
• There are high risk and low risk tumours
• High risk are large,gt2cm, with ill defined
  margin, near the eye

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Presentation

• very slow growing tumour
• Rarely metastasizes
• May appear as a shiny pearly nodule
• Ulceration may occur
• Can be locally destructive with rolled out borders

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Basal cell carcinoma
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Pigmented Nodular Basal Cell Carcinoma
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Basal cell carcinoma, locally destructive
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Treatment

• Surgical excision open with at least a 1.5cm
  margin.
• micrographic surgery by dermatologists(Mohs)
• Radiation therapy
• Topical treatment with 5-fluorouracil for
  superficial tumours
• Cryotherapy

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Squamous cell carcinoma

• A tumour of keratinizing cells of the epidermis
  and is appendages
• Associated with sun exposure and chronic
  inflammation
• Chronic ulcers, sinuses
• Chronic osteomyelitis
• Burn scars
• When it occurs in a previous scar it is called a
  Marjolins ulcer

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Squamous cell carcinoma

• Invariably present as an ulcerated lesion on the
  skin.
• Prognostic factors
• Depththe deeper the depth the worse the
  prognosis
• Surface size lesions .2cm have worse prognosis
  than smaller ones
• Histological grade the higher the broders grade
  the worse the prognosis
• Site tumors on lips and ears have higher chance
  of recurrence
• AetiologyTumours sec to burn scars, o/myelitis,
  skin sinuses chronic ulcers are prone to
  metastasise

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Squamous Cell Carcinoma
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Treatment

• Surgical excision with a 1 cm clearance for
  lesions gt2cm
• Cryosurgery
• FractionatedRadiation therapy

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Malignant melanoma

• Cancer of melanin producingcells (in the skin,
  mucosa, retina and leptomeninges)
• Accounts for , 3 of skin cancers, and accounts
  for 3 of global cancer burden.
• May present as metastatic disease with occult
  primary in 7 of cases

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Risk factors

• Exposure to U/V light recreative exposure to
  sunlight
• Xeroderma pigmentosum
• Past medical history of MM
• History of naevi
• Red hair

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Macroscopic pathology

• Superficial spreading-most common usually arising
  from a previous naevus
• Nodular melanoma, more aggressive, more common in
  men
• Lentigo maligna melanoma, slow growing brown
  macule on the face , neck, hands
• Acral lentigious melanoma affects soles of feet
  and palms of the hands
• Amelanotic melanoma occurs in the GIT

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Superficial Spreading Melanoma

• Most common in middle age
• Develops anywhere on the body, back in both sexes
  and legs in females
• Haphazard combination on colors but may be
  uniformly brown or black

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Acral Lentinginous Melanoma

• Most common in blacks and orientals
• Appears on the palms, soles terminal phalanges
  and mucous membranes
• The tumor is very aggressive and metastasizes
  early

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Nodular Melanoma

• Occurs in the fifth or sixth decade
• More frequent in males with a ratio of 21
• Found anywhere on the body

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Amelanotic Melanoma
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Microscopic features

• Malignant change occurs in melanocytes in the
  basal epidermis then spread along the
  dermo-epidermal junction and although they can
  breach the dermis their spread is mainly radial.

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Classification

• Breslow
• Clarks levels

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Breslow classification

• Depth of invarsionn measured in mm from skin
  surface
• 1equal or less than 1mm
• 2greater than 1 up to 2mm
• 3greater than 2 up to 4mm
• 4greater than 4mm

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Clarks levels

• Level 1 tumour confined to the epidermis
• Level 2tumour invades into the papillary
• Level 3 invarsion into junction of papillary and
  reticular dermis
• Level 4invarsion into the reticular dermis
• Level 5up to subcutaneous sissure

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Treatment

• Excisional biopsy with a margin of 0.5cm(1cm) of
  normal skin and a cuff of subdermal fat in early
  cases
• Regional lymph nodes dissection at the same time
  or after an interval period is controversial.
• Malignant melanoma is not radiosensitive nor
  cheomosensitive