Pediatric Melanoma: One Institution’s Experience With 150 Patients

Abstract

Source: Aldrink JH, Selim MA, Diesen DL, et al. Pediatric melanoma: a single-institution experience. J Pediatr Surg. 2009; 44(8): 1514– 1521; doi: 10.1016/j.jpedsurg.2008.12.003Researchers from Duke University reviewed their experience with pediatric melanoma. The medical records of all children <20 years of age treated for melanoma at their institution between 1973 and 2007 were reviewed. A total of 150 subjects with a mean age of 15.1 years were identified. At the time of diagnosis, 11% were 0 to 11 years of age, 42% were 12 to 16 years, and 47% were 17 to 19 years. Only 2% of the patients were black, all in the youngest age group. Common locations for primary lesions included trunk (37.8% of study patients), extremity (36.5%), and head and neck (24.3%); two children had ocular lesions.Follow-up data were available on 140 patients, with a mean length of follow-up of 8.5 years (range 1 month to 34 years). Overall survival was 84%. Survival in those initially misdiagnosed, however, was 66%. A total of 41 patients developed recurrences (29%), with the highest rate of recurrence among those aged 17 to 19 years at diagnosis (31%). Primary location of the tumor, sex, and thickness of the tumor were not significantly associated with chance of recurrence. Patients initially misdiagnosed had the same risk of recurrence as those who were correctly diagnosed (28.4% and 18.8%, respectively; P=.56). Of the 29 patients who developed metastatic melanoma, 24 died.The authors conclude that pediatric melanoma requires increased awareness by physicians and pathologists to make a timely and accurate diagnosis.Melanoma remains an uncommon diagnosis in the pediatric age group, accounting for only 2% of all melanoma cases.1 Nevertheless, the incidence of melanoma is increasing worldwide and this change is expected to become manifest in children as well.2 Practicing pediatricians and surgeons must work closely with their pathologists to, first, identify those patients who actually require excisional biopsy, and then select those who should proceed with wide excision with lymph node biopsy and further therapy as dictated by depth of lesion and nodal staging.A few definitions are necessary to help clarify discussion of pediatric melanoma. Spitz nevus was originally described in 1948 as a benign juvenile melanoma, an unfortunate term as this lesion is benign yet histologically alarming. This entity continues to present a significant diagnostic challenge to both clinicians and pathologists.3 The pathologist must examine the entire lesion as these melanocytes are atypical, and vary from spindled to epithelioid, but unlike melanoma, are symmetrical, show maturation and junctional cleavage, and lack mitotic figures deep in the dermal melanocytes. Still, expert dermatopathologists can disagree in some cases.Historically, the vertical thickness of the primary tumor and the anatomic depth of invasion are the principle measures in local tumor classification of melanoma staging. Sentinel lymph node biopsy (SLNB) is a methodology increasingly used to stage melanoma. In the current study this procedure was performed in only 18 of the 150 patients, all since the year 2000.1 Blue dye is injected intradermally at the site of the primary melanoma and allowed to be taken up by the lymphatics which then show that the first blue node in the regional lymphatic basin is the node that should contain a metastasis if any tumor is present. This node is termed the sentinel lymph node. The regional lymphatic basin can also be identified by injecting technetium 99m-labeled colloid intradermally at the primary site and then performing lymphatic mapping with a hand-held gamma probe intraoperatively.With accurate diagnosis, the outcomes for pediatric melanoma are very good, with published five-year survival rates of 74% to 89%. Melanoma survival rates among children have continued to improve by 4% per year over the last 30 years. In addition, despite higher rates of positive SLNB, children and adolescents have a lower incidence of recurrence and improved disease-free survival when compared to adults.1,4