Review of Answer Choices (Correct Answer in Green):
A. Incisional partial biopsy
B. Liquid nitrogen cryotherapy
C. Local wide excision with 2 cm margins
D. Close follow-up of the lesion and reassessment in 6 months
Explanation:
A. Incisional partial biopsy: In order to confirm your suspicion of melanoma, you will first need to perform an incisional partial biopsy. Given that this lesion is on a more difficult area of the body to excise and the size of the lesion, 1 or 2 incisional biopsies of the darkest or the raised areas of pigmented lesion with a 4-6 mm punch biopsy (incisional biopsy) are recommended. There is no evidence that an incisional partial biopsy (vs. an excisional biopsy) will adversely affect patient outcome by transferring melanoma cells into cutaneous lymphatics or blood vessels. In fact, biopsy type (incisional vs. excisional) does not affect rates of sentinel lymph node positivity, disease recurrence, or risk of metastasis.
B. Liquid nitrogen cryotherapy: This treatment is indicated for pre-cancerous skin lesions, such as actinic keratoses. As we are concerned that the patient’s lesion could be malignant, this would not be an appropriate choice.
C. Local wide excision with 2 cm margins: As we do not know the results of the pathology report yet, we will not know many important parameters, such as the thickness and depth of invasion of the tumour. These are just a few of the important characteristics we will need in order to determine how large of a margin to leave upon excision. As well in this case, a 2 cm margin may be difficult to achieve given the anatomical location of the melanoma.
D. Close follow-up of the lesion and reassessment in 6 months: We are concerned of ALM given the clinical context, so confirming the diagnosis with biopsy as soon as possible is an important first step in the management of his condition. ALM is a malignant lesion with the potential for metastasis, so following up in 6 months with no initial workup at this appointment would NOT be appropriate.
Additional pathology teaching:
The pathology will include many different characteristics of the tumour. Based on evidence, some of these characteristics are essential to the report and others are optional.
There is strong evidence that Breslow thickness (≤ 1 mm is low risk, > 1 cm is higher risk), ulceration, and dermal mitotic rate are the major independent prognostic factors for survival.
Breslow thickness is important to know in order to properly stage the melanoma tumour. This thickness will also determine how large of a margin you will need for a local wide excision of the tumour.
You may have also heard of Clark levels, which describe the depth of melanoma as it grows into the skin. The current staging system adopted by the American Joint Committee on Cancer (AJCC) no longer considers the Clark level because it has been found to be less prognostic and more subjective than other alternatives.
8th Edition of the AJCC Staging System for Melanoma:
