A 28-year-old woman comes to the office for a periodic recheck of "moles." The patient has a history of multiple irregular melanocytic nevi that have been monitored with regular surveillance, but none of the lesions have required removal. She is concerned about a lesion on her abdomen, which is associated with intermittent itching and has enlarged since her last visit. The patient has a history of recurrent sunburn in childhood. On examination, there are numerous benign-appearing nevi scattered across the body surface. In addition, there is a 2 x 1 cm, pigmented lesion at the lateral abdomen, as shown in the image, which has increased in length since her last visit 6 months ago. Which of the following is the most likely diagnosis?

Question

A 28-year-old woman comes to the office for a periodic recheck of "moles."  The patient has a history of multiple irregular melanocytic nevi that have been monitored with regular surveillance, but none of the lesions have required removal.  She is concerned about a lesion on her abdomen, which is associated with intermittent itching and has enlarged since her last visit.  The patient has a history of recurrent sunburn in childhood.  On examination, there are numerous benign-appearing nevi scattered across the body surface.  In addition, there is a 2 x 1 cm, pigmented lesion at the lateral abdomen, as shown in the image, which has increased in length since her last visit 6 months ago.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

Malignant melanoma is most common in the skin, although it may occur wherever there are pigmented cells, such as the eye and gastrointestinal mucosa. Sunlight exposure is an important factor in the pathogenesis of dermal melanoma, and light-skinned individuals are at greatest risk. Melanomas frequently arise in preexistent dysplastic nevi. Gross findings that suggest melanoma rather than a benign melanocytic nevus include Asymmetric shape, irregular or jagged Border, variability of Color (brown, black, red, blue, or unpigmented), Diameter >6 mm, and Evolution in size and appearance over time (ABCDE criteria). In patients with multiple nevi, a lesion that is significantly different from the patient's typical moles also warrants increased suspicion ("ugly duckling" sign). This patient has risk factors for melanoma and has an enlarging, asymmetric lesion with irregular borders and color variability (Choice D). melanocytic nevus > (Choice A) Café-au-lait spots are benign, lightly pigmented congenital macules. They may be an isolated finding, but the presence of multiple lesions suggests underlying systemic disease (eg, neurofibromatosis). Café-au-lait macules may enlarge somewhat over time, but color variegation, associated itching, and history of severe sunburn are more consistent with melanoma. Café-au-lait spots (Choice B) Discoid lupus is characterized by erythematous, scaling plaques predominantly affecting the face, ears, and scalp. Chronic lesions may develop depigmentation, but enlarging, pigmented lesions are more characteristic of melanoma. scaling plaques depigmentation (Choice C) Lentigo is the result of intraepidermal melanocyte hyperplasia. It is most common in older individuals and is characterized by a round or oval macule with even pigmentation. Lentigo (Choice F) Seborrheic keratosis is a benign pigmented lesion with a well-demarcated border and a velvety or greasy surface. It may be nearly flat, but thickened lesions are often described as having a "stuck on" appearance. Seborrheic keratosis Educational objective: Malignant melanoma may occur wherever there are pigmented cells. Sunlight exposure, hereditary factors, fair skin, and a history of preexistent dysplastic nevi are important risk factors. Findings that suggest melanoma include asymmetric shape, irregular border, variability of color, diameter >6 mm, and evolution in size and appearance over time. >

A 28-Year-Old Woman Comes to the Office for a Periodic