Does a skin lesion of unknown behavior removed by a dermatologist (dermatology specialist) for biopsy indicate melanoma (malignant melanoma)?

From the Guidelines

No, a "skin lesion of unknown behavior" does not mean melanoma. This is a medical coding term used when a dermatologist removes a suspicious spot but doesn't yet know what it is. It simply means they need to wait for the biopsy results to determine the exact diagnosis. The pathologist will examine the tissue under a microscope to identify whether the lesion is benign (non-cancerous), malignant (cancerous), or something else entirely. Many biopsied lesions turn out to be completely harmless.

Key Points to Consider

• The dermatologist will contact you with the results, typically within 1-2 weeks 1.
• If you haven't heard back within that timeframe, it's appropriate to call the office for an update.
• Try not to worry in the meantime, as most skin biopsies do not result in a melanoma diagnosis 1.
• The biopsy was done precisely to determine what the lesion is, rather than assuming the worst.

Diagnosis and Treatment

• Diagnosis should be based on a full thickness excisional biopsy with a small side margin 1.
• Processing by an experienced pathology institute is mandatory.
• The histology report should follow the American Joint Committee on Cancer (AJCC) classification and includes information on the maximum thickness in millimeters (Breslow), information on the mitotic rate, presence of ulceration, presence and extent of regression and clearance of the surgical margins.

Important Considerations

• Dermoscopy by an experienced physician enhances the diagnostic accuracy 1.
• Mutation analysis for BRAF and optionally NRAS and c-Kit are necessary in the case of metastatic disease 1.
• Mutation analysis must be carried out in accredited (certified) institutes including careful quality controls.

From the Research

Diagnosis and Prognosis

• A skin lesion of unknown behavior does not necessarily mean melanoma, as there are various types of skin lesions with different prognoses 2.
• The diagnosis of a malignant lesion involves a systematic approach, including determining whether the lesion is neoplastic or non-neoplastic, and then deciding whether the neoplasm is of epithelial or mesenchymal origin 2.
• The differences between benign and malignant tumors include differentiation, growth rate, growth pattern, and metastasis, with malignant tumors often being poorly differentiated, growing rapidly, and frequently metastasizing 2.

Melanoma Diagnosis and Treatment

• Melanoma is the most common cause of skin cancer-related death in the United States, and cutaneous melanoma is most prevalent in the head and neck 3.
• The treatment of melanoma has been transformed by advances in immunotherapy and genomically targeted therapy, with the 5-year survival rate for metastatic melanoma now greater than 50% 3.
• Wide local excision is considered routine therapy after initial diagnosis of primary melanoma to reduce local recurrences, but it does not impact survival 4.
• Sentinel node staging is recommended for melanomas of intermediate thickness, but its therapeutic effect on survival is still being studied 4.

Adjuvant Therapy for Melanoma

• Adjuvant therapy for melanoma, including targeted therapy and immunotherapy, has shown promise in improving relapse-free survival and overall survival 4, 5, 6.
• The use of adjuvant anti-PD-1 therapy, such as pembrolizumab or nivolumab, has been shown to improve relapse-free survival in some studies, but its benefit in stage IIIA melanoma is still unclear 6.
• Adjuvant BRAF/MEK-targeted therapy, such as dabrafenib + trametinib, has also shown promise in improving relapse-free survival and distant metastasis-free survival in stage IIIA melanoma 6.