Incompletely Characterized Incidental Renal Masses: Emerging Data Support Conservative Management

Abstract

With imaging, most incidental renal masses can be diagnosed promptly and with confidence as being either benign or malignant. For those that cannot, management recommendations can be devised on the basis of a thorough evaluation of imaging features. However, most renal masses are either too small to characterize completely or are detected initially in imaging examinations that are not designed for full evaluation of them. These masses constitute a group of masses that are considered incompletely characterized. On the basis of current published guidelines, many masses warrant additional imaging. However, while the diagnosis of renal cancer at a curable stage remains the first priority, there is the additional need to reduce unnecessary healthcare costs and radiation exposure. As such, emerging data now support foregoing additional imaging for many incompletely characterized renal masses. These data include the low risk of progression to metastases or death for small renal masses that have undergone active surveillance (including biopsy-proven cancers) and a better understanding of how specific imaging features can be used to diagnose their origins. These developments support (a) avoidance of imaging entirely for those incompletely characterized renal masses that are highly likely to be benign cysts and (b) delay of further imaging of small solid masses in selected patients. Although more evidence-based data are needed and comprehensive management algorithms have yet to be defined, these recommendations are medically appropriate and practical, while limiting the imaging of many incompletely characterized incidental renal masses.

Early-stage clear cell tubulopapillary renal cell carcinoma: imaging features and distinction from clear cell and papillary subtypes

“…With the burgeoning role of active surveillance in the management of renal cancer, there is a growing need for ways to help select which patients need prompt treatment and which do not [12,21]. One way to help select patients for active surveillance is to predict their tumors' biological behavior on the basis of histologic subtype.…”

“…Also, both CT and MRI were not available for all patients. However, all patients (except for seven patients whose CT included only an unenhanced phase) were examined using protocols that included integral components for renal mass imaging, image acquisitions before and after intravenous contrast material administration and reconstructions with 3 -5 mm section thickness [12]. The number of patients was overall small because the tumor has been only recently described.…”

“…Therefore, the prospective differentiation of CCTPRCC from the more common subtypes such as clear cell RCC (ccRCC) and papillary RCC (pRCC) at an early stage may be useful for counseling patients on prognosis and treatment plans. For example, an active surveillance approach may be considered in a patient with CCTPRCC [12].…”

Renal cancer at unenhanced CT: imaging features, detection rates, and outcomes

“…However, these exams are typically performed only when a renal cancer is suspected or when an indeterminate renal mass has been previously identified (5–7). When evaluating unenhanced CT of the abdomen for various indications unrelated to renal mass detection and characterization, radiologists are challenged with recognizing renal cancers, and distinguishing them from more common benign etiologies (8). …”

Cistos renais corticais minimamente complexos: avaliação por US, comparação com tomografia computadorizada, ressonância magnética e evolução natural

“…A categoria II-F engloba os cistos complexos que apresentam a maior dificuldade para classificação. Nesta categoria estão as lesões provavelmente benignas, que, no entanto, apresentam algumas características, como por exemplo, elevado número de septos, realce perceptível, porém não mensurável, que requerem acompanhamento com exames de TC ou Ressonância Magnética (RM), em intervalos periódicos ainda não consensuais (até 4 anos segundo alguns autores (18) ), no intuito de demonstrar estabilidade ao longo do tempo, predizendo assim, benignidade 9,10 .…”