Solid pseudopapillary neoplasm, a lesion of uncertain cellular differentiation, is an unusual tumor of the pancreas with an indolent clinical course that typically arises in young females. We report a case of solid pseudopapillary neoplasm arising in a 17-year-old adolescent girl who presented with progressive abdominal pain. The patient underwent surgical resection of an 18 × 14 × 8-cm pancreatic mass that displayed the usual histologic features of a solid pseudopapillary neoplasm in addition to prominent nuclear atypia, increased proliferative index, and extensive necrosis. These unusual histologic findings are rare and are of particular interest owing to the dramatically decreased survival time displayed in this case. Although precise pathologic criteria suggesting a high risk for aggressive behavior of solid pseudopapillary neoplasms are uncertain, recognition of the unusual pathologic features displayed in this case may be useful in the prediction of potentially more aggressive neoplasms that portend a poorer prognosis.