[489] Lethal Childhood Melanoma: A Clinicopathological Study of 12 Cases

Carlos N Prieto-Granada, Cecilia Lezcano, Adriano Piris, Richard Scoyler, Martin Mihm. Baystate Medical Center, Springfield, MA; Brigham and Women's Hospital, Boston, MA; Massachusetts General Hospital, Boston, MA; Sydney Medical School, Sydney, NSW, Australia

Background: Childhood melanoma (CM) is extremely uncommon, representing 3% of pediatric malignancies and 1-4% of all melanoma cases. The incidence of this type of melanoma has been recently increasing at a rate of 1-4% yearly. CM has been associated with better prognosis when compared to adult life melanoma. However, fatal cases have been reported. Melanocytic lesions of childhood can have equivocal morphologic features, often resulting in "borderline" or "uncertain potential" diagnostic labels. In an attempt to identify unambiguous malignant morphologic characteristics of CM, we retrospectively describe the salient features of 12 lesions of CM with fatal outcome.
Design: A retrospective clinicopathological review of 12 pediatric (≤16 years) melanoma patients who died of metastatic disease was performed. The cases were examined by at least one of the authors (MCM, RAS) in private consult services or in an academic setting. The lesions were subclassified and evaluated for prognostic factors. Morphologic evaluation was performed taking in account architectural (pagetoid spread, growth pattern, necrosis) as well as cytomorphological (cell type, cytoplasmic, nuclear characteristics and atypical mitoses) features.
Results: Eight patients were female, 4 were male with a mean age at diagnosis of 9 years. Tumor location was extremities in 4 patients, trunk in 3 patients and head and neck in 3 patients. Mean time from diagnosis to death was 4 years. Mean Breslow thickness was 7.5 mm. and 7 tumors presented as Clark level IV/V lesions. Ulceration was observed in 4 cases. Mean mitotic rate was 7 per mm2 with 8 cases showing atypical mitoses. Architecturally, 10 cases (84%) showed sheet-like growth pattern with infiltrative borders and the most common (9 cases, 75%) cytomorphological features were epithelioid cell type with severe nuclear plemorphism and red macronucleoli.
Conclusions: In summary, in our series of 12 cases we found that the CM features that are likely to be associated with death are large bulky lesions with sheet-like infiltrative growth pattern composed of epithelioid cells with severely plemorphic nuclei and red macronucleoli, in addition to high mitotic activity with atypical forms. The presence of these unequivocal malignant features must prompt the pathologist to confidently render the diagnosis of malignant melanoma in a pediatric patient.
Category: Dermatopathology

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 54, Tuesday Morning

 

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