Spitzoid and non-spitzoid melanoma in children: a prognostic comparative study.

BACKGROUND: Spitzoid melanoma is a rare melanoma subtype often developing in children with unknown biological potential.

OBJECTIVES: To compare the clinical and histopathological factors that influence the biological behaviour between spitzoid and non-spitzoid childhood melanoma, to establish if the spitzoid subset of melanoma has different prognosis than other types of childhood melanomas.

METHODS: A comparison of the prognostic significance of clinical and pathological findings between 38 spitzoid (SM) and 99 non-spitzoid melanomas (N-SM) in children and teenagers younger than 18 years referred to UT - MD Anderson Cancer Center during the period 1992-2007.

RESULTS: Children with SM were significantly younger than those with N-SM, had more frequently multiple melanocytic nevi, nodular melanoma subtype with vertical growth phase, high Breslow thickness and mitotic rate, positive sentinel lymph node biopsy and more advanced stage. N-SM had more often associated nevus. However, the mortality rate in the SM group was lower (5.9%) than in the N-SM group (12.0%). This study has two major limitations. Small size of both groups does not allow reaching statistically significant differences regarding mortality. Using metastatic potential as an inclusion criterion for SM could result in a sample selection bias of the most aggressive group of SM.

CONCLUSIONS: Although SM patients had poorer prognostic factors than N-SM patients, slightly lower mortality rate was detected in the SM group. This less aggressive behaviour could be due to lower potential for widespread distant metastases than conventional melanomas or younger age of children with SM.