Abstract
Differentiation of hemorrhagic hepatic cysts from mucinous cystic neoplasms (MCN) is often difficult on the basis of imaging studies, particularly when the mural nodule is abnormally enhanced after the intravenous injection of contrast medium. We report 3 cases of hemorrhagic hepatic cyst with a characteristic contrast pattern observed during preoperative dynamic CT and MRI studies. In all 3 cases, the following imaging findings suggested the presence of a hemorrhagic hepatic cyst: hyperintense cystic contents on T1-weighted MRI, extreme hypointense area in mural nodules on T2 star-weighted MRI, and a discordance in mural nodule characteristics between US or MRI and CT findings. However, dynamic studies demonstrated focal enhancement during the early phase coupled with progressive centrifugal enhancement during the delayed phase in the mural nodules. The enhancement of the mural nodule did not exclude the possibility of MCN; therefore, we performed a hepatectomy in all 3 cases. Histological examinations showed that the mural nodules were blood clots with organized granulation and vascularization. No malignant cells were observed in either the mural nodules or the cyst walls. The lesions were diagnosed as hemorrhagic hepatic cysts in all 3 cases. Based on these results, the presently described contrast patterns of the dynamic studies performed in these cases, that is, focal enhancement in the mural nodules during the early phase coupled with progressive centrifugal enhancement during the delayed phase, were suggested to be useful imaging features for the accurate diagnosis of hemorrhagic hepatic cysts.
