Renal cell carcinoma (RCC) is one of the most common renal cancers, especially in Western countries (1). Although its incidence has annually increased during the last two decades, the overall mortality rates for RCC in most European countries have declined or stabilized from the early 1990s (2). Renal masses (RMs) are mainly detected through imaging modalities such as abdominal ultrasound (US), computed tomography (CT), or magnetic resonance imaging (MRI), (3). Symptoms such as flank pain, visible hematuria, and observable abdominal mass are rare today as indicators of RCC unless in advanced disease and poor conditions (4).
Extra-renal localization of RCC, defined as the occurrence of RCC in a lesion other than the kidneys, is a rare case that has only been reported several times before. It was noted by other studies that the persistent mesodermal cells of renal lineage in the adrenal gland from fetal development may be the stem of these cancers (5). Previously this condition has been reported in different locations. The first case of extrarenal RCC was reported by Terada et al., as a clear cell RCC with no connection with renal tissue. He reported a possibility of association of this tumor with a minute ectopic kidney (5). Hasan et al., demonstrated a nonmetastatic RCC, primarily diagnosed as an adrenal mass and completely separated from renal tissue (6).
Additionally, extrarenal type 2 papillary renal cell carcinoma (PRCC) has been reported (7). Nunes et al., described an extrarenal RCC, which involved both adrenal glands metachronously (8). In another case report, Costantino et al., presented a case of RCC with bilateral adrenal and liver metastasis without any detectable evidence of a primary tumor in the kidneys (9).
A 52-year-old male presented with left flank pain without a history of weight loss, visible hematuria, or hydronephrosis CT scan revealed a mass that could be either an adrenal tumor, retroperitoneal mass, or a renal upper pole tumor. The patient underwent a ureteroscopy under general anesthesia, and a urethral catheter was inserted. Then in the flank position, open access 10 mm trocar was inserted lateral to the nevus. After the gas insufflation phase, peritoneoscopy was performed. Two five-millimeter trocars were inserted laterally in the proper place. The colon was then medialized, and the ureter was observed in retroperitoneum. The ureter was released along the kidney pedicle, and the renal artery was released (Figure 1). The kidney mass was seen above the junction of the middle and upper renal poles. Its surrounding tissues were released from the Gerota. Although the kidney mass was independent of the capsule, it adhered to its surface. It was gradually released from the capsule and extracted. The capsule beneath the mass was intact, and the site had no bleeding. By low gas pressure, the interior abdomen was checked for hemorrhage. The mass was then placed in endobag and removed from the ten-millimeter port, and the entrance site of this port was sutured. A double-J stent was inserted in the lithotomy position. The pathology examination confirmed nuclear grade 3, rhabdoid features, and RCC. And in immunohistochemistry examination was positive (Figure 2).
Six weeks after surgery double-J stent was removed. Ureteroscopy showed no evidence of stenosis. One month after the double-J stent's departure, an ultrasound was performed again. No evidence of hydronephrosis was seen. Duodenum around the kidney was significantly reduced, and the patient had no complaints of flank pain, hematuria, or fever. Six months later, the patient underwent a spiral computed tomography scan of the abdomen and pelvis. There was no evidence of hydronephrosis or urinoma around the kidney.
Figure 1. Tumor excision and closing of the artery and its vein
Figure 2. Surgical pathology of the left adrenal gland (e haematoxylin and eosin; f racemase). Both specimens presented the same IHC phenotype
At first, based on ultrasound results, it seemed that the extrarenal RCC tumor, in our case, is a part of the kidney. Still, during surgery, we realized that it was completely detached from the kidney with the independent capsule. Although RCC has been infrequently detected in ectopic and supernumerary kidneys, there are only a few reports of extrarenal RCC attached to the kidney (10). Extrarenal RCC is a type that exists in locations other than the normal native kidneys, likely arising from mesonephric remnants. The hypothesis is that extrarenal RCC carcinoma probably arises from mesodermal embryonic remnants (11). In fact, pronephros, mesonephros, and metanephros exist through fetal kidney development, while only metanephros continues and converts to the metanephric blastemal that makes the normal postnatal kidneys. Strangely, the kidneys and the adrenal cortex have their mutual ancestor, the intermediate mesoderm. However, some mesonephric structures can be kept in postnatal life (10,12). Once situated ectopically in the adrenal gland, these mesodermal cells of the renal line can be developed susceptible to cancer transformation (10,13). Extrarenal RCC is occasional, and our case, as the attached apparently to the kidney but detached completely, is interesting. Radiologic and ultrasonographic examinations were not able to detect this detachment. There is suggested by G. Nunes and colleagues that primary extrarenal RCC can be detectable by endoscopic ultrasound with fine-needle aspiration (14).
Rare cases of extrarenal RCC attached to the kidney can be removed without any damage.
All authors had an equal contribution.
Special thanks to the Urology Research Center (URC), Tehran University of Medical Sciences (TUMS).
Conflict of interest
All authors declare that there is not any kind of conflict of interest.
There is no funding.
All authors ensured our manuscript reporting adheres to CARE guidelines for reporting case reports.
Data will be provided by the corresponding author on request.
CT Computed tomography
MRI Magnetic resonance imaging
PRCC Papillary renal cell carcinoma
RCC Renal cell carcinoma
RMs Renal masses