Melanoma is the fifth most common cancer in the United States and one of the deadliest. Tumor depth (Breslow depth) is the most important prognostic factor. Wide local excision is used to manage melanoma stage 0 (in situ) with 0.5- to 1-cm margins, as well as stage IA with 1-cm margins. For lentigo maligna (melanoma in situ), surgical margins wider than 0.5 cm are often necessary to achieve histologically negative margins, and comprehensive margin assessment techniques (Mohs surgery or staged excision) are associated with lower recurrence rates. Localized melanoma with a Breslow depth of less than 0.8 mm and without ulceration has an excellent prognosis and low risk for metastasis; standard treatment is wide local excision with 1-cm margins. Referral is required for melanoma stage IB or higher for discussion of sentinel lymph node biopsy and consideration of adjuvant therapies. Advances in sequencing have enabled tailored therapies for metastatic melanoma based on variations in somatic genes. Immunotherapy has improved survival in those with advanced melanoma. Genetic counseling should be considered for patients with a personal or family history of melanoma or certain other cancers (notably pancreatic cancer, uveal melanoma, mesothelioma, or astrocytoma). After a melanoma diagnosis, patients should undergo full skin examinations at least annually for surveillance.
Nelson M, Hamel RK, Nash J. Skin Cancer: Management of Cutaneous Melanoma. FP Essent. 2026;564:33-39.
Case 4. HP is a healthy 35-year-old man presenting for a health maintenance examination. He frequently goes to the beach for runs but rarely wears sunscreen. You find a 6-mm black nodule on his back. Excisional biopsy with a 1-mm margin confirms nodular melanoma with a Breslow depth of 0.7 mm and no ulceration. Your biopsy margins are narrowly free. HP asks you about the next steps in management.
Background
Melanoma is caused by the malignant transformation of melanocytes, cells that produce melanin. It is the fifth most common cancer in the United States and one of the deadliest.1 The incidence of melanoma varies by Fitzpatrick skin type (see Table 1 in Section One). This system classifies skin types by the skin’s reaction to UV radiation on a scale from I (never tans) to VI (easily tans).1,2 The highest incidence of cutaneous melanoma is in people with Fitzpatrick skin types I and II. However, the highest percentage of late-stage melanoma is in people with types V and VI.1
Table 1 Melanoma Staging and Management
| AJCC stage | Breslow depth | 5-year survival rate (%) | Management | Follow-up |
|---|---|---|---|---|
| 0 | Melanoma in situ; confined to epidermis | 99 | Surgical excision with 0.5- to 1-cm margins* Consider dermatology referral |
Skin examination every 6-12 months for 1-2 years, then annually |
| I | IA: < 0.8 mm without ulceration | 99 | Dermatology referral Surgical excision with 1-cm margin |
Skin examination every 6-12 months for 2-5 years, then annually |
| IB: < 0.8 mm with ulceration; 0.8-1.0 mm; 1.0-2.0 mm without ulceration | 97 | Dermatology referral Surgical oncology referral for Breslow depth of 0.8 mm or greater for possible sentinel lymph node biopsy |
||
| II | IIA: 1-2 mm with ulceration; 2-4 mm without ulceration | 94 | Dermatology and surgical oncology referrals for all, and medical oncology referral for stage IIB or IIC | |
| IIB: > 2-4 mm with ulceration; > 4.0 mm without ulceration | 87 | Skin examination every 3-6 months for 2 years, then at least every 6 months for 3-5 years, then annually Radiologic tests as per specialist recommendations for up to 3-5 years (eg, CT or CT-PET of the chest, abdomen, and pelvis) MRI of the brain |
||
| IIC: > 4.0 mm with ulceration | 82 | |||
| IIIA/B/C/D (regional lymph node spread and/or satellite or in-transit metastasis†) | Any depth | IIIA: 93 IIIB: 83 IIIC: 69 IIID: 32 |
Dermatology and surgical and medical oncology referrals Consider CT or CT-PET Consider CBC, comprehensive metabolic panel Consider genetic testing |
|
| IV (distant metastasis) | Any depth | 15‡ | Dermatology and surgical and medical oncology referrals CT or CT-PET of the chest, abdomen, and pelvis MRI of the brain, lactate dehydrogenase level, CBC, comprehensive metabolic panel Consider genetic testing |
AJCC = American Joint Committee on Cancer; CBC = complete blood cell count; CT = computed tomography; MRI = magnetic resonance imaging;
PET = positron emission tomography.
*—For lentigo maligna (melanoma in situ), margins greater than 0.5 cm may be required because of its ill-defined edges and significant subclinical
extension.
†—Satellite metastases are intralymphatic tumor spread occurring within 2 cm of the primary tumor, and in-transit metastases occur more than 2 cm
from the primary site but before reaching the regional nodal basin.
‡—No 5-year survival estimate is reported in AJCC 8th edition due to emerging therapies; historical 3-year survival is approximately 15%.
Information from references 1 and 4–9.
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