The papillary process: A pseudotumor on coronal and sagittal MRI

Abstract

The papillary process of the caudate lobe can extend posteriorly to lie between the inferior vena cava (IVC) and aorta. Occasionally, the papillary process can wrap around the IVC such that its tip lies posterior to the inferior vena cava. These positions of the papillary process create the potential for its misdiagnosis as a lymph node or mass on coronal and sagittal MRI. To evaluate the frequency that this variant occurs, we retrospectively evaluated contrast axial CT scans in 113 adult patients. Ninety-seven percent had a portion of their papillary process extending posterior to the anterior margin of the IVC. In 66% of the patients, the papillary process overlapped more than 50% of the IVC. In these patients, the papillary process would likely appear as a separate soft tissue structure between the IVC and aorta on coronal MRI. In 12 patients, the papillary process not only extended posterior to lie between the IVC and aorta, but actually extended behind a portion of the inferior vena cava as well. This position of the papillary process could appear as a separate soft tissue structure between the IVC and the diaphragmatic crus on sagittal MRI. The posterior extent of the papillary process between the inferior vena cava and aorta, and occasionally, behind the inferior vena cava, are common anatomical variants, knowledge of which may prevent misdiagnosis on coronal and sagittal MRI.