Multilocular Cystic Renal Cell Carcinoma
Satish K. Tickoo, MD
Victor E. Reuter, MD
Key Facts
Terminology
Multilocular cystic renal cell carcinoma (MC-RCC)
Renal cortical neoplasm composed of numerous clear cell-lined cysts with small clusters of clear cells in tumor septae
Clinical Issues
On mean follow-up of > 6.5 years, no recurrences or metastases described
> 80% cases with stage pT1 disease at presentation
Macroscopic Features
Well circumscribed, almost always with fibrous pseudocapsule
Multicystic cut surface with marked variation in size of cysts
No solid or expansile masses are present in the tumor
Microscopic Pathology
Cyst lining usually consisting of 1 or several layers of neoplastic cells, although in many areas, epithelial lining may be absent
Clusters of tumor cells with clear cytoplasm always present within fibrous septa or in adjacent pseudocapsule
No expansile or solid masses of tumor are evident
Top Differential Diagnoses
Cystic nephroma
Benign multiloculated renal cortical cysts
Cystic partially differentiated nephroblastoma
Cystic clear cell papillary renal cell carcinoma
 Multilocular cystic renal cell carcinoma typically shows a well-circumscribed tumor almost entirely composed of cysts with thin walls, a prominent fibrous capsule, and no solid expansile areas. |
 Microscopic evaluation reveals a tumor entirely composed of variably sized cysts, lined by clear cells with low nuclear grade, and thin septations showing clusters of cells with clear cytoplasm  . |
TERMINOLOGY
Abbreviations
Multilocular cystic renal cell carcinoma (MC-RCC)
Definitions
Renal cortical neoplasm composed of numerous clear cell-lined cysts with small clusters of clear cells in tumor septae
Solid, grossly recognizable component of clear cell RCC should be considered inconsistent with the diagnosis
ETIOLOGY/PATHOGENESIS
Genetic Features
No detailed published studies based on evaluation of a large number of cases available
Results of 1 study, published as an abstract, indicate presence of VHL alterations similar to that in clear cell RCC
These results are considered as evidence in support of its classification as variant of clear cell renal cell carcinoma
CLINICAL ISSUES
Epidemiology
Incidence
2 most recent large studies on combined 76 cases suggest that these constitute approximately 4% of all clear cell RCCs
Although this incidence may not be representative of true clinical practice
Overall, ˜ 160 cases reported in literature
Age
Range of mean age: 46-53 years in different studies (overall range: 30-80)
Gender
M:F = 1.2-2.1:1
Presentation
Up to 90% cases (range: 51-90%) discovered incidentally on radiologic evaluation for non-tumor-related conditions
Unifocal and unilateral, with only rare exceptions
Prognosis
On mean follow-up > 6.5 years, no recurrences or metastases described
> 80% cases with stage pT1 disease at presentation
Very rare cases with stage pT3 disease, and even those with benign outcome
Because of such outcomes, redesignation as multilocular cystic renal cell neoplasm of low malignant potential has been suggested by some
MACROSCOPIC FEATURES
General Features
Well-circumscribed, almost always with fibrous pseudocapsule
Multicystic cut surface with marked variation in size of cysts
Cysts have smooth lining
May contain serous or bloody fluid, or blood clots
Septations are usually quite thin
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