A Case Report of Papillary Renal Cell Carcinoma Seeding along a Percutaneous Biopsy Tract

We report a rare case of a papillary renal cell carcinoma seeding along a percutaneous biopsy tract detected at the time of partial nephrectomy in a 51-year-old man with a 3.5 cm renal mass discovered on computed tomography scan (CT scan). Although renal percutaneous biopsy is now considered as an accurate and safe technique to provide valuable diagnostic information for indeterminate renal lesions, some inherent risks have been reported to associate with this procedure. One of the risks is tumor needle tract seeding, which is a very rare complication of renal percutaneous biopsy. Our well-documented case report could provide some useful information to evaluate the prognosis of patients with tumor seeding along a percutaneous biopsy tract.


Introduction
In the past few years, with the increased use of cross sectional imaging, many small renal masses are discovered in asymptomatic patients. Some of those small renal masses do not present radiological criteria allowing determining the nature of these tumors. 15% to 35% of these incidentally discovered small renal masses are benign after final histological diagnosis [1]. A more precise pretherapeutic diagnosis is now required in order to avoid unnecessary surgical removal. Therefore, percutaneous renal biopsy plays an important role in the management algorithm for those patients [2] [3] [4]. Recent assessments of the safety of renal mass biopsies state that the overall complication rates range from 1.4% to 4.7%, with major complications reported only in 0.46% of all patients undergoing renal mass biopsies [4] [5] [6] [7]. The major complications are tumor tract seeding, bleeding, arteriovenous fistula, infection and pneumothorax.
Needle tract seeding refers to implantation of tumor cells by contamination when instruments like biopsy needles are used to examine, excise or remove a tumor. It can later manifest as a tumor. Some authors believe that tumor seeding may lead to change the tumor stage, convert a resectable tumor into an inoperable one and then worsen the prognosis [8]. The tumor tract seeding has been estimated to be lower than 0.01% [9]. Since 1977 to date, only 15 cases of tumor tract seeding have been reported in the literature [5] [6] [10]- [20]. We describe here an another well documented case, which is the only one encountered in our institution in 205 cases of renal biopsies followed by surgery in 17 years, establishing a frequency of tumor tract seeding of 0.48%.

Clinical Case
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A 51-year-old man with no prior medical history presented with a right flank pain. The CT-scan discovered a 3.5 cm solid renal mass, strictly limited to the kidney ( Figure 1). The patient also had a 3.5 cm cystic lesion that was not ex- The histological finding corresponded to a tumor seeding along the biopsy tract.
Immunohistochemically, the tumor seeding cells were positive for both P504s and CK7 ( Figure 5). The TNM classification was established as pT3a.
The follow up included a CT-scan 2 days after surgery, 2 months later, 9 months later and finally 4 years after diagnosis. They were all unremarkable.      [7]. The seeding-related recurrences, including our case, were detected from one month to 7 years after the initial biopsy. Among the 15 reported cases, 5 of them did not provide follow up information. The rest of patients have been followed from 1 month to 7 years after the discovery of tumor seeding. The majority of them had a follow-up less than two years without local recurrence. One of the patients had 4 local recurrences which happened between 24 months and 53 months after the initial surgery [20]. Two patients died. One of them died 10 months after the diagnosis of seeding which occurred 4 years after total nephrectomy for a papillary carcinoma. Another patient died 14 months after the discovery of tumor seeding and 10 months after cryoablation for a clear cell renal cell carcinoma with Fuhrman grade 2. The prognosis of patients with tumor seeding along a percutaneous biopsy tract needs to be further explored.

Conclusion
The use of needle core biopsy in renal masses is expanding to rule out nonrenal cell primary tumors or benign conditions. The risk of tumor seeding along the needle tract appears to be minimal with modern biopsy techniques, but it cannot be completely avoided. We reported a case with tumor seeding along a percutaneous biopsy tract by using an 18-gauge needle with coaxial sheath and only 2 passes. Our case report may contribute to evaluate the prognosis of patients with tumor seeding along a percutaneous biopsy tract.