Follow-up CT of moderately complex cystic lesions of the kidney (Bosniak category IIF).

OBJECTIVE The purpose of this study is to show the use of follow-up CT studies in the management of moderately complex cystic lesions of the kidney (Bosniak category IIF). MATERIALS AND METHODS The CT scans of 42 moderately complex cystic renal masses (Bosniak category IIF) with follow-up examinations for 2 years or greater or with pathology correlation (n = 3) were retrospectively analyzed by the authors in consensus. The complexity of each lesion was assessed on the basis of the number and appearance of the septa, wall thickness, interface with the kidney parenchyma, presence and amount of calcification, and contrast enhancement characteristics. Lesion size was measured in two dimensions. Follow-up examinations were evaluated for any interval change. RESULTS The average size of the lesions was 3.9 x 3.6 cm, and the average follow-up time was 5.8 years (range, 2 years-18 years 4 months; median, 5.0 years). Eighteen lesions had fewer than five septa, 16 lesions had between five and nine septa, and eight lesions had more than nine septa. In 39 lesions, the wall or septa or both were slightly thickened, and in a single lesion, the wall and septa were hairline thin. The two remaining lesions were of uniformly high attenuation and completely intrarenal. Forty-one lesions had a sharp interface with the kidney, whereas one had an indistinct interface. Twenty lesions contained calcium. Enhancement was not shown in any lesions except for minimal enhancement of smooth walls or septa of some lesions. Follow-up examinations showed that three lesions had developed more calcification, one lesion had increased in overall size but appeared less complex, and three lesions had decreased in size. In addition, two lesions had become more complex and developed thicker septa, and these lesions proved to be cystic neoplasms. CONCLUSION Follow-up CT studies are an effective way of managing patients with moderately complex cystic lesions of the kidney (Bosniak category IIF) because the absence of change supports benignity and progression indicates neoplasm.

[1]  G. Israel,et al.  Calcification in cystic renal masses: is it important in diagnosis? , 2003, Radiology.

[2]  P. Choyke,et al.  Renal masses: quantitative assessment of enhancement with dynamic MR imaging. , 2002, Radiology.

[3]  M. Nishikido,et al.  An evaluation of Bosniak's radiological classification of cystic renal masses , 2000, BJU international.

[4]  S T Cochran,et al.  Cystic renal masses: accurate Bosniak classification requires adequate renal CT. , 2000, AJR. American journal of roentgenology.

[5]  O. Hélénon,et al.  [Cystic tumors of the kidney in adults: radio-histopathologic correlations]. , 1999, Journal de radiologie.

[6]  J. Lloreta,et al.  Cystic renal cell carcinoma: pathological features, survival and implications for treatment. , 1998, British journal of urology.

[7]  J. Eble,et al.  Extensively cystic renal neoplasms: cystic nephroma, cystic partially differentiated nephroblastoma, multilocular cystic renal cell carcinoma, and cystic hamartoma of renal pelvis. , 1998, Seminars in diagnostic pathology.

[8]  M. Bosniak.  Diagnosis and management of patients with complicated cystic lesions of the kidney. , 1997, AJR. American journal of roentgenology.

[9]  P. Humphrey,et al.  CT of cystic renal masses: analysis of diagnostic performance and interobserver variation. , 1997, AJR. American journal of roentgenology.

[10]  M. Bosniak.  The use of the Bosniak classification system for renal cysts and cystic tumors. , 1997, The Journal of urology.

[11]  M. Bosniak.  Problems in the radiologic diagnosis of renal parenchymal tumors. , 1993, The Urologic clinics of North America.

[12]  K. Bauer,et al.  Multilocular cystic renal cell carcinoma. , 1991, American journal of clinical pathology.

[13]  M. Bosniak.  Difficulties in classifying cystic lesions of the kidney , 1991, Urologic radiology.

[14]  D. Hartman,et al.  Cystic renal masses: Usefulness of the bosniak classification , 1991, Urologic radiology.

[15]  M. Bosniak,et al.  The current radiological approach to renal cysts. , 1986, Radiology.

[16]  G. Farrow,et al.  Calcified renal masses. A review of ten years experience at the Mayo Clinic. , 1972, Radiology.