MR imaging findings of an atypical pulmonary hamartoma in a 12-year-old child.

We present the MR imaging findings in an atypical pulmonary hamartoma in a 12-year-old boy. CT showed no evidence of fat or calcifications in the tumour. It demonstrated peripheral rim enhancement on arterial-phase MR images due to a compressed respiratory epithelium, and progression to nearly homogeneous contrast enhancement on delayed-phase images. Small cystic spaces were identified on MR hydrographic and contrast-enhanced images formed by invaginating respiratory epithelium, a unique imaging finding in this condition.