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 % 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

Patients at risk? Risk factorRelative risk Atypical nevus syndrome with personal and family history of melanoma 500 Changing mole>400 Atypical nevus syndrome with family history of melanoma 140 Age ≥ Dysplastic moles7-70

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 5-6 th decade Vertical growth and no horizontal growth phase

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