Module 3 - Skin & Soft Tissue Lesions

Melanoma

Nevus with irregular borders

• ABCD’s of dysplastic nevi:
  

Nevus with multiple colors

• Asymmetry
• Border irregularity
• Colour variegation (tan to brown on pink base)
• Diameter is large (5-12 mm)

• Macular and papular components

• Large birthmarks (>20 cm) have an increased risk of developing into melanoma.
• Nevus with multiple colors

Asymetric Nevus

Superficial spreading melanoma 

• Most common form (70% of melanomas)
• A flat or elevated brown lesion that develops black, blue, red or white pigments; combination of coloured nodules is a hallmark of this melanoma
• Slow growing with lateral spread and irregular borders
• Most often on the upper back of men and women and lower extremities of women
• 50% arise from pre-existing nevi

B. Nodular melanoma

Nodular Melanoma

• Most aggressive form, deeply invading the dermis and subcutaneous tissue
• Rapidly becomes a palpable, elevated, and firm nodule
• Most often seen in elderly and male population; found on any region of the body
• Dark brown, red-brown, or red-black; 5% are flesh coloured (amelanotic)
• Dome-shaped, polypoid, or pedunculated; can ulcerate and bleed
• Most frequently misdiagnosed melanoma because of its similarity to hemagiomas, blood blisters, dermal nevus, seborrheic keratosis, or dermatofibroma.

C. Lentigo maligna melanoma (LMM)

• Large melanotic freckle (3-6 cm) usually found in elderly patients in temple or malar region
• Brown to black macular pigmentation with raised blue to black nodules
• Begins with a radial growth phase known as lentigo maligna (LM) or Hutchinson’s freckle, however less than 10% of LM cases become LMM
• Slow growing (5-20 yrs) and initially flat, becoming elevated and thick

D. Acral Lentiginous Melanoma

Acral Lentiginous Melanoma

• Occurs primarily in dark-pigmented people
• 30-75% of melanomas affecting African Americans, Asians, and Hispanics
• Clinical presentation of lesion similar to LM or LMM
• Found on palms, soles, nail beds and mucous membranes
• Very aggressive melanoma with a higher frequency of metastases

Risk Factors:

• Family or personal history of melanoma
• Blond or red hair
• Freckling of the upper back
• Three or more blistering sunburns before age 20 (UVA/UVB)
• Presence of actinic keratosis
• Blue, green or grey eyes

* Having 3 or more of these increases risk 20-fold:

* 1/3 of melanomas arise from pigmented nevi; ABCD

 

Staging and Prognosis

• Clark levels examine the depth of tumour invasion based on epidermal, dermal and subcutaneous tissue invasion.
• Breslow levels measure the depth of tumour invasion in millimetres and is the preferred method as it is considered more accurate.
• Metastatic lesions in the skin, known as satellites, within 2 cm of the 1o tumour signify poor prognosis with high risk of local recurrence and distant metastasis
• In-transit metastases, noted as metastatic lesions >2 cm away from the 1o tumour, arise from tumour cells in intradermal lymphatics and also signify poor prognosis

Treatment

A. Surgery

• Wide local excision
• Thin melanomas (<1 mm) should have margin of 1 cm
• Thicker and scalp lesions should have margin of 2 cm
• Finger and toes require amputation
• Sentinel Lymph Node Biopsy (SLN) for lesions ≥ 1 mm in depth
• Regional Lymph Node Dissection if sentinel lymph node biopsy is positive
• Resection of metastases

 B. Adjuvant therapies (limited effectiveness observed):

• IFN-alpha2b; IL-2
• BCG
• Vaccines
• Chemotherapy:  DTIC, BCNU, cisplatin, tamoxifen, vincristine
• Radiotherapy

Author: SP Zinn