Diagnostic challenges in bleeding renal tumors: A ruptured papillary renal cell carcinoma showing regression followed by progression

Abstract

A man in his 60s with a history of a right renal tumor presented with right abdominal pain. Imaging revealed tumor rupture with retroperitoneal hemorrhage. Although initial conservative treatment led to temporary tumor shrinkage, significant regrowth occurred over the next 4 years, necessitating radical nephrectomy. The pathological diagnosis was papillary renal cell carcinoma (PRCC). This case highlights the intrinsic fragility of PRCC—a type of renal cancer prone to spontaneous bleeding. It also highlights the importance of considering renal cell carcinoma in the differential diagnosis of renal hemorrhage, not just angiomyolipoma. Notably, PRCC can rupture even with subtle imaging findings. Crucially, this case emphasizes the need for strict and long-term follow-up in conservatively managed ruptured renal tumors because apparent regression does not guarantee complete resolution.

Introduction

Renal cell carcinoma (RCC) is the most common malignant tumor of the kidney. Among its histological subtypes, papillary renal cell carcinoma (PRCC) is the second most common, accounting for 10%–20% of all RCC cases [[1], [2], [3], [4]].

Renal tumor rupture is a rare clinical event and typically presents as a medical emergency. Although renal angiomyolipoma (AML), a benign tumor, is well known for its high risk of spontaneous rupture and retroperitoneal hemorrhage [[5], [6], [7]], rupture of RCC, a malignant tumor, is even rarer. Although PRCC is prone to hemorrhage, it is rarely reported as a primary cause of tumor rupture [[8], [9], [10]].

Here, we present a rare case of a man in his 60s who experienced recent right-sided abdominal pain and was diagnosed with a ruptured renal tumor. The patient underwent conservative treatment and follow-up, during which the tumor exhibited temporary shrinkage. However, the tumor re-enlarged 4 years later and was diagnosed as PRCC.

This case is clinically significant because it demonstrates that PRCC can rupture despite subtle enhancement on imaging. Furthermore, it highlights the importance of monitoring the tumor’s behavior with long-term follow-up after rupture. Through this case report, we discuss the rare phenomenon of spontaneous PRCC rupture, supported by a review of relevant literature.

Case report

A man in his 60s, who had been under observation for a right renal tumor (maximum diameter: 4 cm), presented with a recent onset of right-sided abdominal pain.

Initial laboratory investigations revealed leukocytosis, elevated inflammatory markers, and anemia. The patient’s past medical history included bladder cancer (treated with transurethral resection 15 years prior), surgery for prostatic enlargement, hypertension (on cilnidipine), and hyperlipidemia (on atorvastatin).

His social history included a 20-pack-year history of smoking and daily beer consumption.

Abdominal dynamic contrast-enhanced computed tomography (CT) was performed for further investigation. Noncontrast-enhanced CT revealed a high-attenuation mass (maximum diameter of 7 cm) in the upper pole of the right kidney, consistent with hemorrhage, with an associated hematoma extending into the perirenal space and along Gerota’s fascia and the diaphragm. Although hematoma was evident, there was no contrast medium extravasation or ongoing active bleeding at the time of imaging in either the arterial or equilibrium phases (Fig. 1). Based on the aforementioned findings, recent rupture of the right renal tumor was suspected. After 7 days of conservative management with rest and analgesia, noncontrast-enhanced CT confirmed that the hematoma size was stable, and the patient was discharged.

Fig. 1.

Abdominal CT. (A) Noncontrast-enhanced axial CT. (B) Contrast-enhanced axial CT during the arterial phase and (C) Contrast-enhanced axial CT during the equilibrium phase. (B and C are the same level as A.). A high attenuating mass (maximum diameter of 7 cm) was observed in the upper pole of the right kidney (A, arrow), showing no contrast enhancement (B and C, arrow). Rupture of the right renal tumor was suspected. Hemorrhage and hematoma were seen extending from the upper pole of the right kidney to the perirenal space and along Gerota’s fascia and the diaphragm; although hematoma was evident, there was no contrast medium extravasation or ongoing active bleeding at the time of imaging in either the arterial or equilibrium phases. The crescent-shaped enhancing area located at the anterior margin of the hematoma represented normal renal parenchyma rather than contrast leakage.

To further evaluate the renal tumor, abdominal magnetic resonance imaging (MRI) was performed 3 weeks later (Fig. 2) and showed no clear fat content suggestive of AML. The lesion exhibited features of hemorrhage and necrosis. Follow-up imaging at 2 months (CT), 4 months (MRI), and 9 months (MRI) (Fig. 3) revealed significant shrinkage of the tumor. Considering these findings, nephrectomy was deferred in favor of continued observation with serial imaging. The patient was then lost to follow-up at our institution for 4 years. However, upon the patient’s return, a follow-up examination revealed that the tumor had grown significantly (Fig. 4).

Fig. 2.

Magnetic resonance imaging (MRI) 3 weeks after initial CT. (A) Axial T1-weighted images (T1WI), opposed-phase. (B) Axial T1WI, in-phase. (C) Axial fat-suppressed T2-weighted images (T2WI). (D) Diffusion-weighted images (DWI) (b-value, 1,000 s/mm2). (E) ADC map. MRI performed for 3 weeks after CT shows a significant reduction in tumor size (maximum diameter of 5.8 cm). The mass exhibited high signal intensity predominantly at the periphery on T1WI, whereas most of the lesion demonstrated low signal intensity. (A and B). There was no evidence of fat content on T1-weighted in-phase and out-of-phase imaging (A and B). Fat-suppressed T2WI revealed heterogeneous high signal intensity within the mass. The mass was well-demarcated from the normal renal parenchyma and demonstrated a low signal intensity capsule on fat-suppressed T2WI (C, arrow). The mass exhibited markedly high signal intensity on DWI (D) and low ADC values (E).

Fig. 3.

Abdominal plain MRI 9 months after initial CT. (A) Axial T1WI and (B) Axial fat-suppressed T2WI.

The mass in the upper pole of the right kidney shows marked reduction and regression (maximum diameter of 3.4 cm). The internal high signal intensity on T1WI has decreased (A).

Fig. 4.

Abdominal dynamic contrast-enhanced CT 4 years after initial CT. (A) Noncontrast-enhanced axial CT. (B) Contrast-enhanced axial CT during the arterial phase. (C) Contrast-enhanced axial CT during the equilibrium phase. A CT scan performed 4 years later reveals a marked increase in tumor size to 8 cm. The internal portion appeared necrotic and of low density; however, a solid component was observed at the periphery, indicating significant tumor growth. A soft tissue, low-density mass with contrast enhancement was observed along the diaphragm (arrow).

Radical nephrectomy with en bloc partial diaphragmatic resection was performed. Macroscopically, a well-demarcated, tan-colored solid tumor with partial hemorrhage and necrosis was observed (Fig. 5). Histologically, cuboidal tumor cells with prominent nucleoli were seen proliferating in tubular and papillary structures (Figs. 6A and B), with areas of hemorrhage and necrosis. The findings were consistent with PRCC (Type I). The tumor exhibited infiltration into the perirenal adipose tissue and was displacing and abutting the diaphragm; however, no direct invasion into the diaphragm was observed (Fig. 6C). In the peritumoral area adjacent to the diaphragm, a foamy histiocyte reaction, foreign body reaction, and fibrosis were observed. These findings, in conjunction with the patient’s clinical history, were considered consistent with the site of the previous tumor rupture.

Fig. 5.

Gross specimen. Grossly, a well-demarcated, tan-colored solid tumor with focal hemorrhage and necrosis is observed.

Fig. 6.

Histological findings. (A) Hematoxylin and eosin (H&E) stain, low-power field. (B) H&E stain, high-power field. (C) Invasion of the renal capsule and (D) Tumor adjacent to the diaphragm. Histologically, cuboidal tumor cells with prominent nucleoli proliferated, forming papillary and tubular structures (A and B). Hemorrhage and necrosis were also observed. The findings were consistent with PRCC (type I). The tumor exhibited infiltration into the perirenal adipose tissue and abutted/compressed the diaphragm; however, no direct invasion into the diaphragm (*) was observed (C).

Discussion

Renal tumor rupture represents a rare yet clinically urgent event, requiring prompt diagnosis and management [[5], [6], [7], [8], [9], [10], [11], [12]]. Although rupture is often associated with highly vascular benign tumors, such as AML, the possibility of RCC rupture, though considered even rarer [[5], [6], [7], [8], [9], [10], [11], [12]], must always be a key consideration in the differential diagnosis. Initial CT imaging in such cases can present diagnostic challenges; for instance, a mass with poor enhancement and no overt contrast extravasation may initially lead to AML as a primary consideration, potentially obscuring a malignant etiology.

In the case presented here, a man in his 60s developed right-sided abdominal pain. Imaging revealed a ruptured right renal tumor and retroperitoneal hemorrhage. Despite initial CT findings that suggested a ruptured tumor, AML was also considered likely due to its frequency. Although a neoplastic lesion was suspected, both urologists and radiologists considered the mass atypical for AML due to the absence of fat on MRI. The lack of contrast enhancement and marked tumor shrinkage prevented a definitive diagnosis.

The definitive diagnosis of PRCC was ultimately established following histological examination, which importantly lacked the characteristic fat components, smooth muscle, or abnormal vasculature typical of AML. As the second most common subtype of RCC, PRCC is intrinsically prone to tumor necrosis and hemorrhage [5,[8], [9], [10], [11], [12]]. This inherent fragility suggests that PRCC can indeed rupture even in the absence of the vigorous enhancement patterns often associated with other aggressive renal tumors.

Several cases of ruptured PRCC have been reported in the literature [4,7,11], but most were diagnosed and surgically treated at presentation. The unique feature of our case was the marked temporary regression after rupture, which led to deferred nephrectomy and subsequent regrowth after 4 years. This prolonged course underscores the potential for misleading imaging appearances and highlights the importance of long-term vigilance.

A particularly unique and clinically misleading aspect of this case was the tumor’s significant shrinkage over the 9 months following conservative management. This temporary regression was attributable to a confluence of factors, including the mechanical compression from hematoma formation and localized ischemia and inflammation induced by the rupture itself. Most importantly, this notable regression unfortunately contributed to the temporary discontinuation of the patient’s medical visits because the apparent improvement may have provided a false sense of security regarding the tumor’s resolution.

The rationale for deferring nephrectomy was based on the patient’s stable clinical condition, the absence of ongoing hemorrhage or contrast extravasation, and the marked regression of the mass. However, our experience suggests that conservative management should be accompanied by strict follow-up. Based on previous reports, we recommend imaging at 3–6-month intervals for at least 2–3 years, with shorter imaging intervals (every 3 months) during the first year, with surgical intervention considered if regrowth is detected.

Nevertheless, despite the initial impressive regression, the tumor subsequently re-enlarged several years later due to the re-proliferation of residual tumor cells. Subsequent histological examination of the excised specimen unequivocally confirmed this complex clinical course. It revealed not only evidence of a past rupture site, characterized by a foamy histiocyte reaction, foreign body reaction, and fibrosis, but also confirmed the malignant spread of tumor cells, including directly beneath the diaphragm. These findings highlight that even significant temporary tumor shrinkage does not equate to complete tumor eradication.

In conclusion, this rare case of ruptured PRCC offers crucial insights: temporary tumor shrinkage following conservative treatment does not indicate complete resolution and cannot rule out future regrowth from residual cancer cells. PRCC should be strongly considered in the differential diagnosis of ruptured renal tumors, particularly when imaging shows poor enhancement but lacks fat content, as in our case. Apparent regression on imaging should not be mistaken for full recovery, and long-term surveillance is essential. Further research is required to pinpoint the best follow-up timelines for conservative management and to determine the ideal time for surgery if tumor regrowth occurs.

Patient consent

Informed consent was obtained for the publication of this case report.