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The lesion on this 12-year-old girl’s trunk has been present since birth, growing slowly as she has. Recently, an abrasion sustained during a basketball game caused the lesion to become swollen and tender. It has since returned to its original size and nontender state, but the change in appearance raised enough concern to prompt dermatologic consultation.
The child is otherwise healthy and reports having had very few sunburns, tanning easily (though seldom).
EXAMINATION
The lesion—an oval, nevoid, hair-bearing, uniformly brown plaque with a mammilated surface—is located on the right lower anterior abdominal wall and measures just short of 3 cm x 2 cm. It bears no sign of the recent trauma. The margins are clearly defined, and the lesion is nontender on palpation. No increased warmth is detected.
Overall, the patient’s type III skin has little, if any, evidence of excessive sun exposure.
What is the diagnosis?
DISCUSSION
Congenital melanocytic nevi (CMNs) affect about 1% of newborns, appearing within months after birth. There is no unanimity in opinion regarding their origin, although they appear to be hereditary in some cases.
About 50% of CMNs occur on the trunk and 15% on the head or neck; the rest are scattered about on the extremities. The distinctive morphologic appearance of the lesion helps to distinguish it from other items in the differential, such as warts or cancer.
Only rarely do CMNs raise concern for malignant potential. (Trauma cannot cause a benign lesion to undergo malignant transformation.) So-called “giant” CMNs (> 20 cm) appear to be associated with the greatest risk, though the incidence of melanoma in children younger than 9 is only about 0.7 cases per million. Of particular concern are “bathing trunk” CMNs, which occasionally cover more than half of the body; affected patients need special attention from pediatric dermatologists who have the appropriate experience.
Neither “small” (< 2 cm) nor “medium” CMNs (> 2 cm, < 20 cm) are particularly worrisome in terms of malignancy. But depending on the location and original size, CMNs can become the object of unwanted attention or ridicule from peers—a little 1-cm lesion on an infant’s neck can grow four to six times its original size by puberty. And at that point, excision becomes much more problematic due to the likelihood of scarring.
Therefore, many experts advise excising some lesions early on, while the lesion and resulting scar are small—and before the child has a chance to develop any anxiety over it. If not excised, CMNs simply need to be watched for change (size, uniformity of color, and border).
TAKE-HOME LEARNING POINTS
- Congenital melanocytic nevi (CMNs) < 20 cm in diameter are generally quite safe but can grow much larger—often becoming a source of ridicule.
- Depending on the size, location, and appearance of the lesion, excision is justifiable before it has a chance to grow and become problematic.
- Children younger than 10 almost never develop melanoma (the rate is 0.7 cases per million)—and even when they do, it is almost never related to malignant transformation of a CMN.
- Trauma cannot cause a benign lesion to undergo malignant transformation.
The lesion on this 12-year-old girl’s trunk has been present since birth, growing slowly as she has. Recently, an abrasion sustained during a basketball game caused the lesion to become swollen and tender. It has since returned to its original size and nontender state, but the change in appearance raised enough concern to prompt dermatologic consultation.
The child is otherwise healthy and reports having had very few sunburns, tanning easily (though seldom).
EXAMINATION
The lesion—an oval, nevoid, hair-bearing, uniformly brown plaque with a mammilated surface—is located on the right lower anterior abdominal wall and measures just short of 3 cm x 2 cm. It bears no sign of the recent trauma. The margins are clearly defined, and the lesion is nontender on palpation. No increased warmth is detected.
Overall, the patient’s type III skin has little, if any, evidence of excessive sun exposure.
What is the diagnosis?
DISCUSSION
Congenital melanocytic nevi (CMNs) affect about 1% of newborns, appearing within months after birth. There is no unanimity in opinion regarding their origin, although they appear to be hereditary in some cases.
About 50% of CMNs occur on the trunk and 15% on the head or neck; the rest are scattered about on the extremities. The distinctive morphologic appearance of the lesion helps to distinguish it from other items in the differential, such as warts or cancer.
Only rarely do CMNs raise concern for malignant potential. (Trauma cannot cause a benign lesion to undergo malignant transformation.) So-called “giant” CMNs (> 20 cm) appear to be associated with the greatest risk, though the incidence of melanoma in children younger than 9 is only about 0.7 cases per million. Of particular concern are “bathing trunk” CMNs, which occasionally cover more than half of the body; affected patients need special attention from pediatric dermatologists who have the appropriate experience.
Neither “small” (< 2 cm) nor “medium” CMNs (> 2 cm, < 20 cm) are particularly worrisome in terms of malignancy. But depending on the location and original size, CMNs can become the object of unwanted attention or ridicule from peers—a little 1-cm lesion on an infant’s neck can grow four to six times its original size by puberty. And at that point, excision becomes much more problematic due to the likelihood of scarring.
Therefore, many experts advise excising some lesions early on, while the lesion and resulting scar are small—and before the child has a chance to develop any anxiety over it. If not excised, CMNs simply need to be watched for change (size, uniformity of color, and border).
TAKE-HOME LEARNING POINTS
- Congenital melanocytic nevi (CMNs) < 20 cm in diameter are generally quite safe but can grow much larger—often becoming a source of ridicule.
- Depending on the size, location, and appearance of the lesion, excision is justifiable before it has a chance to grow and become problematic.
- Children younger than 10 almost never develop melanoma (the rate is 0.7 cases per million)—and even when they do, it is almost never related to malignant transformation of a CMN.
- Trauma cannot cause a benign lesion to undergo malignant transformation.
The lesion on this 12-year-old girl’s trunk has been present since birth, growing slowly as she has. Recently, an abrasion sustained during a basketball game caused the lesion to become swollen and tender. It has since returned to its original size and nontender state, but the change in appearance raised enough concern to prompt dermatologic consultation.
The child is otherwise healthy and reports having had very few sunburns, tanning easily (though seldom).
EXAMINATION
The lesion—an oval, nevoid, hair-bearing, uniformly brown plaque with a mammilated surface—is located on the right lower anterior abdominal wall and measures just short of 3 cm x 2 cm. It bears no sign of the recent trauma. The margins are clearly defined, and the lesion is nontender on palpation. No increased warmth is detected.
Overall, the patient’s type III skin has little, if any, evidence of excessive sun exposure.
What is the diagnosis?
DISCUSSION
Congenital melanocytic nevi (CMNs) affect about 1% of newborns, appearing within months after birth. There is no unanimity in opinion regarding their origin, although they appear to be hereditary in some cases.
About 50% of CMNs occur on the trunk and 15% on the head or neck; the rest are scattered about on the extremities. The distinctive morphologic appearance of the lesion helps to distinguish it from other items in the differential, such as warts or cancer.
Only rarely do CMNs raise concern for malignant potential. (Trauma cannot cause a benign lesion to undergo malignant transformation.) So-called “giant” CMNs (> 20 cm) appear to be associated with the greatest risk, though the incidence of melanoma in children younger than 9 is only about 0.7 cases per million. Of particular concern are “bathing trunk” CMNs, which occasionally cover more than half of the body; affected patients need special attention from pediatric dermatologists who have the appropriate experience.
Neither “small” (< 2 cm) nor “medium” CMNs (> 2 cm, < 20 cm) are particularly worrisome in terms of malignancy. But depending on the location and original size, CMNs can become the object of unwanted attention or ridicule from peers—a little 1-cm lesion on an infant’s neck can grow four to six times its original size by puberty. And at that point, excision becomes much more problematic due to the likelihood of scarring.
Therefore, many experts advise excising some lesions early on, while the lesion and resulting scar are small—and before the child has a chance to develop any anxiety over it. If not excised, CMNs simply need to be watched for change (size, uniformity of color, and border).
TAKE-HOME LEARNING POINTS
- Congenital melanocytic nevi (CMNs) < 20 cm in diameter are generally quite safe but can grow much larger—often becoming a source of ridicule.
- Depending on the size, location, and appearance of the lesion, excision is justifiable before it has a chance to grow and become problematic.
- Children younger than 10 almost never develop melanoma (the rate is 0.7 cases per million)—and even when they do, it is almost never related to malignant transformation of a CMN.
- Trauma cannot cause a benign lesion to undergo malignant transformation.
