PORTLAND, ORE. — Melanoma in a pediatric patient is a lot like Sasquatch, Dr. Seth Orlow remarked at the annual meeting of the Pacific Northwest Dermatological Society.
It's a very rare thing to see, but if it's around, you surely don't want to miss it.
Drawing from case series large and small and from his own experience, Dr. Orlow painted a puzzling picture of childhood melanoma, from the hodgepodge of clinical features to highly variable survival figures.
Perhaps the only absolutely clear conclusion in the literature is that melanoma in children is exceedingly rare, even in referral centers seeing a large number of patients with suspicious lesions, said Dr. Orlow, director of pediatric and adolescent dermatology and chair of dermatology at New York University.
A SEER (Surveillance, Epidemiology, and End Results) database analysis of 140,206 cases of melanoma diagnosed between 1973 and 2001 found just 1,255 cases in patients under 20 years old; 204 of these were melanoma in situ, and just 95 occurred in children younger than 10 years of age.
The overall incidence of childhood melanoma rose 2.9% per year. In children younger than 10, the incidence rose 1.4% per year.
Younger children were less likely than older children with melanoma to be in a traditional high-risk category.
They were more likely to be nonwhite, have nodular lesions, present with head/face/neck primaries, and have metastatic disease. Many had a history of other malignancies and may have received radiation therapy and/or chemotherapy for leukemia or another cancer, Dr. Orlow said.
Other studies similarly have found few traditional risk factors, frustrating dermatologists who might hope they can simply raise the red flag for a fair-skinned child with a history of blistering sunburns.
“We feel, with some reason, we can identify adults who are at high risk. We know if you have a family history, you have many atypical nevi, you have a history of blistering sunburns, if you're red-haired and freckled, you're going to have an increased risk of melanoma” as an adult, he said.
“In prepubescent melanoma, all bets are off,” Dr. Orlow said.
Children diagnosed with melanoma represent a rainbow of skin types.
Most of them have no family history of the disease, and many have no precursor lesions.
A series from Milan's Istituto Nazionale Tumori found that 14 of 33 children under age 14 years who were diagnosed with melanoma had amelanotic lesions.
“There's no way 40% of adults' lesions would be amelanotic,” he said.
Dr. Orlow's own patients over 16 years of practicing at New York University have included a 16-year-old Jamaican girl with a primary lesion that looked like a keloid on her thigh, a 14-year-old Peruvian girl with a fingertip lesion, a 12-year-old Russian boy from Chernobyl with a lesion on the lower back, and a 12-year-old Ashkenazic girl with a small (less than 1 mm) shoulder lesion.
Another speaker at the meeting, Dr. Joseph Gruss of the University of Washington, Seattle, described a case of metastatic melanoma present at birth in an African American girl with a large scalp lesion.
The bottom line is that pediatric melanoma is a mysterious disease that calls for an open mind.
“These are not the things you're used to seeing in older children and adults. It is a very different disease,” Dr. Orlow said.
Survival of melanoma in adulthood is fairly well predicted by lesion characteristics and other factors, but the survival of childhood melanoma is neither well-characterized nor consistent from study to study.
“You'll see wildly different numbers from different centers,” he commented.
For example, among 13 cases in children under 17 years old seen at Montreal's Hopital Ste. Justine over a 22-year period, the 5-year survival was 59%.
Among 23 cases referred to Children's Hospital in Boston and reviewed by Dr. Ray Barnhill, a dermatopathologist, survival appeared linked to tumor type (Semin. Diagn. Pathol. 1998;15:189–94).
All five cases he characterized as “small cell melanoma” were fatal. There was no precursor lesion in four of the five, and two of the five were verrucous, Dr. Orlow said.
Of six cases of “adultlike melanoma,” two were fatal. Both were on the backs of older children in the series.
One of the three patients with “Spitz-like melanoma” died, but none of the nine with “atypical Spitz tumors” did. It is doubtful that the latter cases were really melanomas at all, Dr. Orlow said.
The Milan series cited a survival rate of 90% in children under age 10 years and 47% in children over 10, in a pattern that did not seem to correlate with the apparent severity of presenting features.