WBR0802

Author	[[PageAuthor::Gonzalo A. Romero, M.D. [1]]]
Exam Type	USMLE Step 2 CK
Main Category	Surgery
Sub Category	Dermatology, Dermatology
Prompt	[[Prompt::A 42-year-old blond man originally from Portland at age 17 and has been working as a fisherman in the Caribbean. He comes to the clinic complaining of multiple nevi. He recently noticed that one of them has changed in appearance and is enlarging. The nevus has multiple colors within the lesion, irregular borders and measures 1.9 cm. A picture of the lesion is shown below. Which of the following is the most important prognostic predictor? ]]
Answer A	Diameter
Answer A Explanation	Incorrect. A nevus larger than 5mm in diameter is suspected to be melanoma. The characteristics of melanoma are ABCDE: asymmetry or abnormal shape, irregular borders, several colors within the lesion, and diameter larger than 6 mm and enlargement. It can also present with itchiness or tenderness.
Answer B	Color
Answer B Explanation	Incorrect.
Answer C	Depth of invasion
Answer C Explanation	Correct. See overall explanation
Answer D	Multiple nevi
Answer D Explanation	Incorrect. Multiple nevi is not a sign of malignancy nor a prognostic factor for melanoma.
Answer E	Lymph involvement
Answer E Explanation	Incorrect. Less invasive melanomas even with lymph node metastases carry a better prognosis than deep melanomas without regional metastasis at time of staging
Right Answer	C
Explanation	[[Explanation::Features that affect prognosis are tumor thickness in millimeters (Breslow's depth), depth related to skin structures (Clark level), type of melanoma, presence of ulceration, presence of lymphatic/perineural invasion, presence of tumor infiltrating lymphocytes (if present, prognosis is better), location of lesion, presence of satellite lesions, and presence of regional or distant metastasis. Certain types of melanoma have worse prognoses but this is explained by their thickness. Interestingly, less invasive melanomas even with lymph node metastases carry a better prognosis than deep melanomas without regional metastasis at time of staging. Local recurrences tend to behave similarly to a primary unless they are at the site of a wide local excision (as opposed to a staged excision or punch/shave excision) since these recurrences tend to indicate lymphatic invasion. This is an example of a black, irregularly shaped, uniformly brown pigmented nevus on a 19-year-old man's right cheek. The Breslow index measured 2.88 mm, and a thorough medical evaluation revealed no evidence of metastases. The scar was reexcised with a 2-cm margin, and the skin was repaired with a graft. Educational Objective: Breslow's depth is used as a prognostic factor in melanoma of the skin. It is a description of how deeply tumor cells have invaded. References: http://www.ncbi.nlm.nih.gov/pubmed/16258493?dopt=Abstract See also: Melanoma and Breslow's depth Educational Objective: References: ]]
Approved	No
Keyword	melanoma, skin cancer
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