腎細胞癌術後之異時性甲狀腺和膀胱轉移 - 案例報告

許程皓¹, 張延驊^1,2, 黃逸修^1,2

臺北榮民總醫院泌尿部¹；國立陽明交通大學醫學院泌尿學科及書田泌尿科學研究中心²

Metachronous metastases of renal cell carcinoma to the 

thyroid and bladder - A case report

Chen-Hao Hsu¹, Yen-Hwa Chang^1,2, Eric Yi-Hsiu Huang^1,2

¹ Department of Urology, Taipei Veterans General Hospital, Taipei, Taiwan

² Department of Urology, College of Medicine and Shu-Tien Urological Science 

Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan

Introduction:

Renal cell carcinomas (RCCs) represent approximately 80% of primary renal malignancies, with more than 400,000 new cases diagnosed and over 170,000 deaths reported annually worldwide. [1] About 16% of patients with RCC present with metastasis, commonly affecting the liver, lungs, brain, and bones. In this case report, we present a rare case of metachronous metastases of RCC to both the thyroid and bladder.

Case presentation:

A 56-year-old woman, previously diagnosed with clear cell renal cell carcinoma (RCC) of the left kidney, underwent left open radical nephrectomy (ORN) in January 2012. The initial staging of the tumor was pT2b cN0 cM0, Fuhrman grade 2.

In February 2022, she detected a palpable mass on the left side of her neck and sought help at our Endocrinology outpatient clinic. Thyroid sonography revealed nodules in both lobes of the thyroid, with the largest measuring 5.5 cm on the left. Fine needle aspiration was performed, and cytology indicated atypia. Subsequently, a total thyroidectomy was carried out on March 21, 2022. Pathological examination revealed bilateral papillary microcarcinoma (pT1) and metastatic clear cell RCC in the left lobe of the thyroid.

In May 2024, during a routine follow-up, a CT scan disclosed a 1.8 cm polypoid lesion on the left lateral wall of the urinary bladder. Cystoscopy confirmed a hypervascularized nodular lesion originating from a thickened stalk with engorged vessels. Transurethral resection of the bladder tumor (TURBT) was performed on June 13, 2024 (Fig. 1 & 2). Pathology reported metastatic carcinoma consistent with clear cell RCC of renal origin. A whole-body PET scan performed in July 2024 showed no signs of recurrence or further metastasis.

Discussions:

The lungs are the most common site for RCC metastasis, occurring in approximately 50% of cases, followed by the liver, bones, and lymph nodes, which account for about 20-30%. Brain metastasis is observed in around 10% of cases. Metastasis to endocrine organs, such as the thyroid and pancreas, is much rarer (<3% of cases). Even more unusual is the spread of RCC to the urinary bladder, which is exceedingly rare, with only a few cases reported in the literature. [3] According to a case report by Smart et al. (2022), RCC metastasis to the bladder represents an uncommon site of recurrence and unpredictable metastatic patterns of RCC. [4]

In our case, the bladder metastasis was detected 12 years after the initial nephrectomy, emphasizing the unpredictable and long latency period of RCC metastases. Metastases to the bladder are often discovered during routine surveillance imaging or following the onset of hematuria or lower urinary tract symptoms.

The development of metachronous metastases has been documented in RCC, with cases reported as late as 10 to 20 years post-nephrectomy. These delayed recurrences highlight the importance of long-term follow-up in RCC patients, even when they are asymptomatic for extended periods. The combination of two rare metastatic sites in the same patient further underscores the heterogeneous nature of RCC.

Conclusion:

This case report highlights the unpredictable metastatic pattern of RCC, with rare occurrences of metachronous metastases to the thyroid and bladder. It emphasizes the need for long-term follow-up in RCC patients, as metastases may present many years after the initial treatment. Early detection and appropriate surgical management remain crucial for improving outcomes in these rare cases of metastatic RCC.