Multilocular cystic renal cell carcinoma: a series of 12 cases and review of the literature.

OBJECTIVES

To assess the presentation and diagnosis of, and treatment options for, multilocular cystic renal cell carcinoma (MCRCC). MCRCC is a rare entity and the true incidence and biologic behavior of MCRCC are not well known.

METHODS

We reviewed the pathology files at the Queen Elizabeth II Health Sciences Centre for a 9-year period (1991 to 2000). All cases of RCC with a cystic component were identified. The clinical features, radiologic features, surgical procedure, pathologic features, and follow-up outcomes of the MCRCC cases were studied.

RESULTS

We identified 12 cases of MCRCC comprising 3.1% of the RCC cases. The tumor was incidentally found in 67% of the cases. Ultrasonography was found to be a useful screening test, but computed tomography is the imaging study of choice to identify malignant features. Magnetic resonance imaging can be used in equivocal cases. For treatment, radical nephrectomy was done in 58% and partial nephrectomy in 33%. The mean tumor size was 3.4 cm. The mean solid component of the tumor was 9.5%. The mean tumor grade was 1.1. None of the 10 patients (83%) available for follow-up showed any evidence of recurrence. They were followed up for an average of 42.5 months.

CONCLUSIONS

MCRCC is an uncommon subtype (3%) of RCC. The term MCRCC should be used exclusively to identify cystic RCC with a small volume (25% or less) of neoplastic clear cells in the cyst walls. The benign clinical course of these lesions suggests that patients may benefit from nephron-sparing surgery.