The FP suspected melanoma and recommended immediate biopsy. The patient consented, and the physician performed a broad shave biopsy that included most of the pigmented lesion. Pathology revealed a lentigo maligna melanoma with a Breslow depth of 0.3 mm.
Lentigo maligna melanoma occurs in 4% to 15% of cutaneous melanomas. It’s similar to the superficial spreading type and appears as a flat (or mildly elevated) mottled tan, brown, or dark-brown discoloration. This type of melanoma is found most often in the elderly and arises on chronically sun-exposed, damaged skin on the face, ears, arms, and upper trunk. The average age of onset is 65 years and it grows slowly over 5 to 20 years.
When melanoma is suspected, it’s best to provide a specimen with adequate depth and breadth. Unfortunately, choosing the darkest and most raised area does not guarantee the correct diagnosis in a partial biopsy.
In cases of suspected lentigo maligna melanoma on the face, a broad shave provides a better sample than a punch biopsy. The broad shave biopsy (also known as saucerization) is best performed with a razor blade. (See the Watch & Learn video on “Shave biopsy.”)
In this case, the relatively small size of the lesion and the high risk for melanoma would make an elliptical excisional biopsy a good alternative. The saucerization has the advantage of being quick and easy to perform so that it can be done on the day that the melanoma is suspected.
This patient was referred for Mohs surgery for complete excision and repair. A sentinel lymph node biopsy was not indicated, and the prognosis for this stage Ia melanoma was relatively good.
Photos and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Mayeaux, EJ, Usatine, R. Lentigo maligna. In: Usatine R, Smith M, Mayeaux EJ, et al. Color Atlas of Family Medicine. 2nd ed. New York, NY: McGraw-Hill; 2013:981-984.
To learn more about the Color Atlas of Family Medicine, see: www.amazon.com/Color-Family-Medicine-Richard-Usatine/dp/0071769641/.
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