Multiple subtypes of pediatric melanoma may be fatal

Multiple subtypes and clinical presentations of pediatric melanoma led to fatal disease, according to a study.

Elena B. Hawryluk, MD, PhD, of the department of dermatology at Harvard Medical School and Boston Children’s Hospital, and colleagues described pediatric melanoma as “rare and diagnostically challenging.”

In the multicenter, retrospective study, they reviewed findings for 38 fatal cases among patients aged 20 years or younger to characterize clinical and histopathologic features of fatal pediatric melanoma.

Eligible participants had been diagnosed between 1994 and 2017. The cohort was 57% white and 19% Hispanic, with an average age at diagnosis of 12.7 years (range, 0.0 to 19.9 years). The average age at death was 15.6 years (range, 1.2 to 26.2 years).

Among 16 cases with known identifiable subtypes, half were nodular, 31% were superficial spreading and 19% were spitzoid melanoma.

Looking at the full cohort, 10 of 38 cases carried associations with congenital melanocytic nevi. Of the six cases with known size, five were large, which the researchers defined as 20 cm or greater projected adult size, or giant, which was defined as 40 cm or greater projected adult size.

In 30 cases, the location of the lesion was described. The most common locations were eight that occurred on the back, six on the scalp, four on the face and three on the arm.

For the 25 cases that included data on tumor depth, the median Breslow thickness was 2.2 mm (range, 0.9 mm to 36 mm). The median mitotic rate was 3.5 per mm² (range, 1 per mm² to 30 per mm²) for the 18 cases reporting on this feature.

Clinicians observed metastases in 97% of cases, with 92% demonstrating distant metastases.

For the nine patients in whom BRAF testing was conducted, seven were positive for this mutation.

The researchers said that roughly three-quarters of patients were diagnosed in adolescence and that adolescent disease tends to be more aggressive than childhood disease.

“Pediatric melanoma can be fatal in diverse clinical presentations, including a striking prevalence of Hispanic patients compared to adult disease, and with a range of clinical subtypes, although no fatal cases of spitzoid melanoma were diagnosed during childhood,” the researchers wrote.