Primary lung adenocarcinomas in children and adolescents treated for pediatric malignancies.

INTRODUCTION: Primary lung adenocarcinoma is extremely rare in the pediatric age group. There have been anecdotal reports of lesions that are histologically indistinguishable from adult-type pulmonary adenocarcinoma in young patients after treatment for nonpulmonary cancers. Herein, we present clinical, histopathologic, and molecular data on eight such cases.
METHODS: Histopathologic evaluation of the tumors was performed according to the World Health Organization classification. Molecular studies for EGFR and KRAS mutations were performed on six patients with sufficient material.
RESULTS: All eight patients were never smokers, four males and four females. Median age at nonpulmonary cancer diagnosis was 14 years (range, 3-23 years). Pulmonary adenocarcinomas were diagnosed at a median age of 15 years (range, 10-24 years); tumors were 0.1 to 2.0 cm in size and in some cases coexisted with metastases from the original cancer. Retrospective review showed that in at least three patients, the nodules were radiographically present before chemotherapy. Of six patients whose tumors were tested for common EGFR and KRAS mutations, two were positive for the former and one for the latter. At a median follow-up of 11 months (range, 2-29 months), six patients remained well without lung nodules and two had additional small, peripheral lung nodules that have not been biopsied.
CONCLUSIONS: Pulmonary lesions found in young patients with pediatric cancers can be histologically indistinguishable from lung adenocarcinoma seen in adults, may display typical adenocarcinoma-associated mutations of EGFR and KRAS, and may precede the administration of cytotoxic chemotherapy.