tubulozystisches Nierenzellkarzinom
Tubulocystic renal cell carcinomas are a rare subtype of renal cell carcinoma (RCC) with predominantly cystic appearance.
Terminology
Tubulocystic RCC was first identified as a distinct histopathologic entity in 2005, and subsequently acknowledged as an independent disease category in the 2016 WHO classification of renal tumors .
Epidemiology
Peak incidence occurs in the 6 through 8 decades.
Males are much more commonly affected than females (7:1 ratio).
Associations
- papillary renal cell carcinoma coexists in the same kidney in up to 50% (in small cases series )
Clinical presentation
Most patients are asymptomatic and the tumor is discovered incidentally.
Pathology
Macroscopically, the tumors are well-circumscribed lesions comprising extensive tiny cysts with numerous thin septa, resulting in a spongy or "bubble wrap" appearance. Microscopically, the tumor is composed of tubular and cystic spaces separated by fibrous stroma.
Limited information from genetic studies suggest gene expression similar to papillary RCC .
Radiographic appearance
Ultrasound
- markedly hyperechoic (70%)
- posterior acoustic enhancement (50%), consistent with cystic nature
- no internal vascularity on color Doppler
CT
- variable attenuation so may appear solid or cystic
- C+: contrast enhancement is usually mild or indeterminate given small amount of solid tissue
MRI
- T2: hyperintense due to cystic component, with septa
- T1 C+ (Gd): mild enhancement in small solid components or wall
Treatment and prognosis
Surgical resection is curative. Recurrence and/or metastasis occur in less than 10% of cases.
Differential diagnosis
- cystic renal tumors
- hyperechoic renal tumors