Follicular Thyroid Carcinoma Arising After Hematopoietic Stem Cell Transplantation in a Child with Pleuropulmonary Blastoma

Background: Pleuropulmonary blastoma (PPB) is a rare and aggressive intrathoracic neoplasm that is associated with other dysplastic or neoplastic conditions. The prognosis, especially of type II (cystic and solid) and type III (solid) PPB, is poor. High-dose chemotherapy (HDC) and hematopoietic stem cell transplantation (HSCT) have been attempted to improve survival rates. We report the development of follicular thyroid carcinoma in a girl who was treated at a young age for PPB. Summary: A 23-month-old girl was evaluated for a clinical diagnosis of pneumonia and was found to have a mass in the left lung that grew rapidly. It was removed and diagnosed as a PPB. At the age of two, she was referred to our hospital for further treatment. She received adjuvant chemotherapy for 6 months but developed a recurred mass in her back at 4.3 years of age. After removal of the mass, she was given a salvage chemotherapy followed by HDC and HSCT but not radiation treatment between 4.4 and 4.9 years of age. At the age of seven, after 2 years without treatment, she presented with multiple thyroid nodules in both lobes that steadily grew over the next 2 years. At the age of nine, she underwent total thyroidectomy, which revealed an invasive follicular carcinoma. She remained without clinical evidence of thyroid cancer for one year since the surgery. Radiation therapy was not administered because of the concerns of causing another malignancy. A literature search combined with the present case indicated that, of the five living patients who had been treated with HDC and HSCT, three developed a follicular thyroid carcinoma. Conclusions: The high prevalence (3/5, 60%) of follicular thyroid carcinoma in patients with PPB who were treated with HDC and HSCT is striking. This suggests that, in patients with PPB, either HDC or HSCT contributes to the development of thyroid cancer. Clinicians should be advised of the high risk of thyroid carcinoma occurrence when HDC and HSCT are being contemplated in children with PPB.