Name : Morteza
Family :Sanei Taheri
Affiliation : Radiology Department,Shohada Tajrish Hospital,SBMU
Academic Degree: Associate Professor of Radiology
Resident : Hussein Soleiman Tabar
Gender : Female
Age : 36
36-year-old female with acute left flank pain
Imaging Procedures and Findings
Noncontrast images show a well-defined and homogeneous hyperdense lesion in left kidney. After contrast administration the lesion shows no enhancement at all.
Hemorrhagic renal cyst is the result of bleeding into a pre-existing simple renal cyst. The typical renal cyst is a round, well-defined, non-enhancing lesion with a density of less than 15 Hounsfield units (HU) (simple cyst renal). Because of the presence of blood products, the attenuation of a hemorrhagic cyst measures approximately 60-90 HU. On unenhanced CT, it may be of the same or greater attenuation as renal parenchyma. It is a common cause of the "hyperdense cyst", and it may be misinterpreted as a solid lesion on enhanced CT images. A true hemorrhagic cyst should not show any enhancement. Comparison of the pre- and postcontrast-enhanced images may be necessary prior to reaching a conclusion. Except for the increased density, a hemorrhagic cyst manifests the other characteristics of a simple cyst. Sonographically, internal echoes are visualized, and these may be mobile. A fluid debris level and decreased through-sound transmission are secondary sonographic findings. No blood flow should be detected with Doppler imaging. On MRI, a hemorrhagic cyst may be of high signal on all pulse sequences due to the presence of methemoglobin. Because the more paramagnetic products of methemoglobin tend to settle to the dependent portions of the cyst, there may be a fluid-hemoglobin level (more intense at the bottom of the cyst) on T1-weighted images. The relative intensities of the layers may reverse on T2-weighted images. In contrast, a renal cell carcinoma would appear heterogeneous, indistinct or irregular, and lacking of a fluid-hemoglobin level. Bosniak has classified cystic renal lesions into four radiological categories, class I being a benign lesion with no atypical features and class IV being a lesion which is highly suspicious for malignancy. A hemorrhagic cyst is usually a class II lesion because the presence of hemorrhage is an atypical feature. Lesions of this group are usually followed radiologically to assess for stability.
Renal hemorrhagic cyst