Two children developed papillary thyroid carcinoma after allogeneic bo
ne marrow transplantation (BMT) probably due to radiotherapy during re
mission and pretransplantation conditioning. Establishing a relationsh
ip between the cellular thyroid stimulating hormone (TSH) effect and d
evelopment of carcinoma in cases with high serum TSH concentrations is
difficult. After BMT, patients should be regularly followed up with t
hyroid ultrasound and, when nodularity is found, fine needle aspiratio
n and/or open biopsy are recommended.