Melanoma

Hai Ho, M.D.

Department of Family Practice

Epidemiology

Sixth most common cancer Incidence increases from 1/1500 in

1930 to 1/75 in 2000 1% of skin cancer but account for 60%

of skin cancer death

Risk factors?

Sun exposure Intermittent intense exposure Childhood

UVB > UVA – higher incidence near equator

Tanning bed

Clinical prediction rule

American Cancer Society’s

ABCDE

A

B

C

D

Melanoma could occur in lesions less than 6 mm

E

Elevation or Enlargement by patient report

Sensitivity of ABCDE rule

If melanoma truly exists, the rule will detect it 92-97% (average 93%) of the

time, when one criterion is met

Caution

If none of the criteria is met, 99.8% chance that the lesion is not a melanoma (high negative predictive value)

May miss amelanotic melanomas and melanomas changing in size

Growth patterns

Radial growth Lasts for months to years Growth and regression due to restraint by

immunologic system Horizontal and vertical growth

More poorly differentiated Produce nodule or mass

Superficial spreading melanoma

50% of melanoma cases Common in middle age Radial spread and regression

White = regression

Nodular melanoma

20-25% of melanoma cases Common in 5-6th decade Vertical growth and no horizontal growth

phase

Lentigo maligna melanoma

15% of melanoma cases Elderly – 6-7th decade Lentigo maligna

Horizontal growth phase for years Bizarre shapes from years of growth and regression Transform to lentigo maligna melanoma

Lentigo maligna

Lentigo maligna melanoma

Acral-lentigious melanoma

10% of melanoma cases In palms, soles, terminal phalanges, and mucous membrane Growth phase similar to lentigo maligna and lentigo maligna

melanoma Aggressive tumor and early metastasis

Excisional biopsy

Preferred method – deepest level of penetration for staging

Punch biopsy

Wound <4mm may not be sutured

Subcutaneous fats

Stretch the skin perpendicular to the skin line

Shaving

Never because prognosis and treatment are based on the level and depth of invasion

Pathology

Depth of invasion Growth pattern (nodular, superficial

spreading, etc.) Margin status Presence or absence of ulceration

Depth of invasion

Breslow

•Measure the actual thickness

•More reproducible and accurate in determining prognosis

Clark

•Report by anatomical site

•Significant if tumor ≥ 1mm

Indications for regional node biopsy

Thickness 1-4 mm Thickness < 1mm

Has <10% of nodal metastasis no biopsy Ulceration, truncal location, and male gender,

either alone or in combination consider biopsy to evaluate nodal metastasis

Thickness > 4mm Has 65-70% distant metastasis no biopsy

Histological examination of nodes

Reverse transcriptase polymerase chain reaction (RT-PCR) assay detects of tyrosinase messenger RNA, a melanocyte-specific marker, in lymph nodes with metastasis

Immunohistochemistry techniques

Staging

Depth of invasion Regional nodal metastasis Distance metastasis

Survival rate

LDH

Prognostic indicator for distant metastasis in stage IV

Cutaneous excision

Recommendations from Academy of Dermatology

A margin of 0.5 cm of normal skin is recommended for in situ melanomas.

A 1 cm margin is recommended for melanomas <2 mm thick

A 2 cm margin is recommended for melanomas 2 mm thick

Other recommendations

Surgical margin of 3 cm for T3 (2.1 to 4.0 mm) or T4 (>4 mm) primary tumors

No correlation between thickness > 4mm and surgical margin (Heaton et al. Ann Surg Oncol 1998)

In >4mm thickness, outcome is probably based more on regional and distant metastasis

Head and neck melanomas

Face and scalp – high recurrence rate Complex regional node drainage

Parotid and cervical lymphatics are common sites of spread

Parotid node dissection – risk of CN VII injury Limited skin – skin graft Post-op adjuvant radiation for unsatisfactory

margin and desmoplastic neurotropic melanomas

Subungual melanoma

Fingers Amputation DIP Cutaneous excision and skin graft for

proximal lesions Toes

Amputation at MTP

Plantar melanoma

Cutaneous excision with skin graft due to lack of surplus skin

Positive sentinel nodes

Regional lymph node dissection

Noncerebral metastatic melanoma

Cytotoxic chemotherapy Immunotherapy such as interferon Pallative

Radiation Surgery

Cerebral metastatic melanoma

Surgery Whole brain radiation therapy And/or stereotactic radiosurgery