Multilocular Cystic Renal Neoplasm of Low Malignant Potential
Definition
- Neoplasm of the kidney composed entirely of cysts with small groups of non-expansile clear cells in the septa
- These tumors have been named carcinomas (probably not very sensibly) because they are composed of cells indistinguishable from conventional clear cell carcinoma cells
Alternate/Historical Names
- Multilocular renal cell carcinoma
- Multilocular cystic renal cell carcinoma
Diagnostic Criteria
- All of the following criteria must be met to make this diagnosis
- Circumscribed nodule composed entirely of cysts and septa
- Cysts are non-communicating
- Cysts lined by single layer of low grade clear cells
- May be largely denuded
- No papillary growth pattern
- Cysts separated by fibrous septa
- May calcify or ossify
- Lacks ovarian type cellular stroma
- Groups of low grade clear cells are permitted within the septa
- Must not be expansile nodules or show infiltrative growth
- Cells indistinguishable from conventional clear cell carcinoma cells
- Nuclear/nucleolar grade 1 or 2
- May exhibit increased vascularity
- May be infrequent
- Must be distinguished from histiocytes and lymphocytes
- Keratin or EMA stain may aid in identification
- Features not allowed:
- Necrosis
- Vascular invasioin
- Sarcomatous differentiation
- The tumor must be extensively, or preferably entirely, sampled to make this diagnosis
- The presence of any expansile nodules of clear cells in the septa between the cysts indicate an ordinary, fully malignant, clear cell carcinoma with cystic change
- Circumscribed nodule composed entirely of cysts and septa
Kurt Schaberg MD
John P Higgins MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting / last update:: 1/24/11, 11/1/16
