Tumor metastásico en tejido blando a nivel del sacro secundario a carcinoma de células claras de riñón. Reporte de caso / Metastatic tumor in soft tissue at the level of the sacrum secondary toclear cell carcinoma of the kidney. A case report

Introducción. El cáncer de riñón es la undécima neoplasia maligna más común en los Estados Unidos Mexicanos. El carcinoma de células claras de riñón (CCR) es considerado la estirpe más frecuente y representa el 2-3 % de todos los cánceres a nivel mundial. En el contexto de la enfermedad metastásica, por lo general se identifica un tumor renal primario y las metástasis se localizan en pulmón, hueso, hígado, cerebro y, raramente, en tejidos blandos. Los pacientes con metástasis a tejidos blandos no tienen síntomas en las etapas iniciales y generalmente se identifican sólo cuando las lesiones aumentan de tamaño o durante el estudio de la pieza de resección quirúrgica. Caso clínico. Se presenta el caso de una paciente en la séptima década de la vida, con una metástasis en tejidos blandos de la región sacra, de 10 años de evolución posterior a una nefrectomía secundario a CCR. Resultados. Hallazgos clínicos e imagenológicos de un tumor bien delimitado. Se realizó resección quirúrgica de la lesión, bajo anestesia regional, con extirpación completa. Conclusión. Se recomienda que los pacientes con un sitio metastásico resecable y solitario sean llevados a resección quirúrgica con márgenes libres, como fue el caso de nuestra paciente, por su fácil acceso y ser una lesión única. En el CCR, además de su tratamiento quirúrgico inicial, es indispensable una estrecha vigilancia con examen físico e imágenes transversales, para detectar la presencia de metástasis y con ello evitar tratamientos tardíos.

Introduction. Kidney cancer is the eleventh most common malignancy in the United States of Mexico. Carcinoma renal cell (CRC) is considered the most frequent type and represents 2-3% of all cancers worldwide. In the setting of metastatic disease, a primary renal tumor is usually identified, and metastases are located in the lung, bone, liver, brain, and rarely in soft tissue. Patients with soft tissue metastases do not have symptoms in the initial stages and are generally found only when the lesions increase in size or during the study of the surgical resection piece. Clinical case. In this case, we report a female patient in the seventh decade of life with a soft tissue metastasis located in the sacral region, 10 years after a nephrectomy secondary to CRC. Results. Clinical and radiological findings of a well-defined tumor. Surgical resection of the lesion is performed under regional anesthesia with complete excision. Conclusions. It is recommended that patients with a resectable and solitary metastatic site be candidates for surgical resection with free margins, as was the case with our patient due to its easy access and single lesion. In CRC, in addition to its initial surgical treatment, close surveillance with physical examination and cross-sectional images is essential to monitor the presence of metastases and thus avoid late treatments.

Cysts or necrotic components in pancreatic ductal adenocarcinoma is associated with the risk of EUS-FNA/B complications including needle tract seeding.

BACKGROUND: EUS-FNA/B for pancreatic ductal adenocarcinoma (PDAC) is generally considered to be safe; however, while the incidence is low, there are occurrences of complications. Among these complications, there are serious ones like needle tract seeding (NTS), and it is not known than which types of tumors have the risks of EUS-FNA/B complications. This study aimed to evaluate the risk of EUS-FNA/B complications in patients with PDAC, focusing on morphological features. METHODS: Overall, 442 patients who underwent EUS-FNA/B for solid pancreatic masses between January 2018 and May 2022 in four institutions were retrospectively surveyed. Finally, 361 patients histopathologically diagnosed with PDAC were analyzed. Among these patients, 79 tumors with cysts or necrotic components were compared with 282 tumors without cysts or necrotic components. The incidence and risk of EUS-FNA/B complications including NTS were evaluated. RESULTS: There were 9 (2.4 %) of total EUS-FNA/B complications and 3 (0.8 %) of NTS. The incidence of total complication rate and NTS in tumors with cysts or necrotic components were significantly higher than in those without cysts or necrotic components (total complication 6.3 % vs. 1.4 %, p = 0.026, NTS 3.7 % vs. 0 %, p = 0.01). The transgastric route of puncture (OR: 93.3, 95 % CI: 3.81-2284.23) and the existence of cysts or necrotic components (OR: 7.3, 95 % CI: 1.47-36.19) were risk factors for EUS-FNA/B complications identified by the multivariate analysis. CONCLUSIONS: We should pay attention to the risks of EUS-FNA/B complications, including NTS, when the tumor has cysts or necrotic components.

Factors associated with increased risk of peritoneal seeding after radiofrequency ablation for hepatocellular carcinoma.

PURPOSE: To evaluate the incidence, risk factors, and prognosis associated with peritoneal seeding after percutaneous radiofrequency ablation (RFA) for HCC, focusing on viable tumors after previous locoregional treatment, including TACE and RFA. METHODS: Exactly 290 patients (mean age, 67.9 years ± 9.74; 223 men) with 383 HCCs (mean size, 15.9 mm ± 5.49) who underwent RFA between June 2012 and December 2019 were included in this retrospective study. Among them, 158 had history of previous treatment (mean number, 1.3 ± 1.8) with 109 viable HCCs. Cumulative seeding after RFA was estimated using the Kaplan-Meier method. Independent factors affecting seeding were investigated using multivariable Cox proportional hazards regression analysis. RESULTS: Median follow-up was 1175 days (range: 28-4116). Seeding incidence was 4.1 (12/290) and 4.7% (17/383) per patient and tumor, respectively. The median time interval between RFA and detection of seeding was 785 days (range: 81-1961). Independent risk factors for seeding included subcapsular tumor location (hazard ratio [HR] 4.2; 95% confidence interval [CI] 1.4, 13.0; p = 0.012) and RFA for viable HCC after previous locoregional treatment (HR 4.5; 95% CI 1.7, 12.3; p = 0.003). Subgroup analysis for viable tumors, revealed no significant difference in cumulative seeding rates between the TACE and RFA groups (p = 0.078). Cumulative overall survival rates differed significantly between patients with and without seeding metastases (p < 0.001). CONCLUSION: Peritoneal seeding after RFA is a rare, delayed complication. Subcapsular-located and viable HCC after previous locoregional treatment are potential risk factors for seeding. Seeding metastases could affect the prognosis of patients who cannot receive local therapy.

Hematoma-Filled Pneumatocele after CT-Guided Percutaneous Transthoracic Needle Lung Biopsy: Two Case Reports.

CT-guided percutaneous transthoracic needle biopsy (PTNB) plays a key role in the diagnosis of pulmonary abnormalities. Although the procedure is considered safe and effective, there exists a potential for complications, such as pneumothorax, hemorrhage, hemoptysis, air embolism, and tumor seeding. However, pneumatoceles after CT-guided PTNB have been rarely reported. Herein, we report two cases of pneumatoceles that developed immediately after PTNB for primary lung cancer. A pneumatocele filled with hematoma should be considered in cases with a newly developed nodule along the needle tract during short-term follow-up CT after PTNB.

Subcutaneous Implantation of Hepatocellular Carcinoma in a Dog.

A 13-year-old male neutered Cocker Spaniel mixed-breed dog developed a subcutaneous mass 2 years after undergoing surgery to remove a hepatocellular carcinoma. An approximately 4 × 3 cm subcutaneous mass was found on the ventral abdomen at the cranial end of the abdominal incision from the previous surgery. The subcutaneous mass was surgically removed and histopathological examination determined that it was an implantation of the previously excised hepatocellular carcinoma. The diagnosis was confirmed by immunohistochemical labelling with hepatocyte paraffin 1 antibody and pancytokeratin. Based on the location of the subcutaneous mass at the cranial end of the abdominal incision associated with the previous hepatocellular carcinoma resection, it is likely there was iatrogenic metastasis from the primary tumour excision. Subcutaneous iatrogenic metastasis of hepatocellular carcinoma is well recognized in humans but has apparently never been reported in dogs. Clinicians should be aware of this potential surgical complication.

Breast Metastasis of Lung Cancer After Computed Tomography-Guided Core Needle Biopsy: A Case Report.

Background: Needle tract metastasis is a rare complication following percutaneous procedures for malignancy. Case Summary: This report describes a 49-year-old female with a lump on her right breast. Mass core needle biopsy showed the specimen was an invasive carcinoma, and mastectomy with sentinel lymph node biopsy was performed. What is special about this case was that the patient reported a history of lung cancer and the position of the breast mass was the puncture site of computed tomography-guided core needle biopsy for lung cancer. Immunostaining of paraffin specimen findings indicated the breast mass as a result of lung carcinoma metastasis. The patient's medical history indicated that the malignant tumor in the breast was a core needle tract pulmonary metastasis. The patient underwent the examination and received therapy based on the lung cancer metastasis principle. At 9 months from breast surgery, the patient is alive, in good condition, and with stability of the disease. Conclusions: This patient was misdiagnosed. Careful medical history review and multidisciplinary team discussions are important, especially for patients with a history of cancer or invasive operation.

The impact of preoperative EUS-FNA for distal resectable pancreatic cancer: Is it really effective enough to take risks?

BACKGROUND AND AIMS: Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is frequently used for the preoperative histologic diagnosis of pancreatic cancer. However, debate continues regarding the clinical merits of preoperative EUS-FNA for the management of resectable pancreatic cancer. We aimed to evaluate the benefits and safety of preoperative EUS-FNA for resectable distal pancreatic cancer. METHODS: The medical records of 304 consecutive patients with suspected distal pancreatic cancer who underwent EUS-FNA were retrospectively reviewed to evaluate the clinical benefits of preoperative EUS-FNA. We also reviewed the medical records of 528 patients diagnosed with distal pancreatic cancer who underwent distal pancreatectomy with or without EUS-FNA. The recurrence rates and cancer-free survival periods of patients who did or did not undergo preoperative EUS-FNA were compared. RESULTS: The diagnostic accuracy of preoperative EUS-FNA was high (sensitivity, 87.5%; specificity, 100%; positive predictive value 100%; accuracy, 90.7%; negative predictive value, 73.8%). Among patients, 26.7% (79/304) avoided surgery based on the preoperative EUS-FNA findings. Of the 528 patients who underwent distal pancreatectomy, 193 patients received EUS-FNA and 335 did not. During follow-up (median 21.7 months), the recurrence rate was similar in the two groups (EUS-FNA, 72.7%; non-EUS-FNA, 75%; P = 0.58). The median cancer-free survival was also similar (P = 0.58); however, gastric wall recurrence was only encountered in the patients with EUS-FNA (n = 2). CONCLUSION: Preoperative EUS-FNA is not associated with increased risks of cancer-specific or overall survival. However, clinicians must consider the potential risks of needle tract seeding, and care should be taken when selecting patients.

Tumour Seeding After a Thoracic Biopsy for Renal Cell Carcinoma: A Case Report and a Review of the Literature.

The role of percutaneous tumour biopsies had gain importance in the management of renal cell carcinoma to provide diagnostic specimen for the patients with metastatic disease that could benefit a systemic treatment. Among the possible complications of this procedure, however, there is the risk of tumoral cells seeding along the biopsy's tract; this complication, albeit being reported as anecdotal, could have devastating effects. Here we report a case of a young male who developed subcutaneous chest metastasis of renal cell carcinoma after a biopsy of a lung nodule. We subsequently reviewed other cases reported in literature.

Seeding of Gastrostomy Tube Site in Patient With Squamous Cell Carcinoma of the Tongue: A Case Report.

Enteral nutrition (EN) is a widely used therapeutic tool to provide nutrition support for patients with various clinical conditions, including different types of cancer. Head and neck cancers, often complicated by dysphagia, are among leading indications for enteral feeding. Percutaneous endoscopic gastrostomy (PEG) and percutaneous endoscopic jejunostomy (PEJ) tubes are typically used to deliver EN. This article presents a case report of a young male with squamous cell carcinoma of the tongue. Unfortunately, he developed metastasis of his cancer at the right lateral side of the PEG placement site, requiring surgical resection of seeded growth at the PEG site. This rare complication can be challenging, as it requires a high index of suspicion to diagnose and can potentially limit nutrition support options. A number of theories have been proposed to explain seeding during PEG/PEJ placement, including direct repositioning of malignant cells during instrumentation. A specific placement technique has not been shown to be superior, as seeding was reported with all placement techniques. However, given the lack of statistically powerful studies to describe this entity, there are still gaps we need to explore to better understand seeding of feeding tubes and best practices around diagnosis and early treatment. EN continues to be an important part of caring for patients with cancer during active or palliative treatments. Understanding potential risks in the setting of cancer metastasis is beneficial to the patients and multidisciplinary teams involved. Early recognition of possible seeding of feeding tube sites is necessary to ensure subsequent timely surgical intervention.

Late recurrence of papillary thyroid cancer from needle tract implantation after core needle biopsy: A case report.

BACKGROUND: Papillary thyroid cancer (PTC) has good prognosis so that the local recurrence or distant metastasis can occur later on the lifetime follow up. In this study, we report recurrence of PTC in subcutaneous area combined with lymph node metastasis. A suspicion of needle tract implantation after core needle biopsy was found. CASE SUMMARY: A 66-year-old female patients who underwent right thyroid lobectomy for PTC complained of palpable nodule on anterior neck area. The location of the palpable nodule was not associated with her postoperative scar. After excision of the skin tumor, it was diagnosed as recurrence of PTC. Furthermore, results of subsequent imaging showed lymph node metastasis on her right cervical area. According to the previous medical records, the patient received core needle biopsy through the neck of the patient midline and hematoma was noted after the procedure. The time interval from the first diagnosis to local recurrence or metastasis to the skin and lymph nodes was ten years. As treatment, the patient underwent lymph node dissection in the right and completion thyroidectomy for radioisotope treatment. CONCLUSION: Needle tract implantation can occur after core needle biopsy. Further studies are needed to compare core-needle biopsy and fine-needle aspiration.

Clinical Characteristics of High-Grade Glioma with Primary Leptomeningeal Seeding at Initial Diagnosis in a Single Center Study.

BACKGROUND: High-grade glioma (HGG) with primary leptomeningeal seeding (PLS) at initial diagnosis is rare. The purpose of this study was to identify its clinical features and to describe the clinical treatment outcomes. METHODS: We retrospectively reviewed the medical records of patients with HGG (World Health Organization grade III or IV) at our institution between 2004 and 2019, and patients with PLS at the initial diagnosis were enrolled in the study. Clinical features, such as the location of leptomeningeal seeding, surgical methods, and degree of resection, were sorted based on electronic medical records also containing performance scale, and hematological and serological evaluations. Radiological findings and immunohistochemical categories were confirmed. Furthermore, we sought to determine whether controlling intracranial pressure (ICP) via early cerebrospinal fluid (CSF) diversion increases overall survival (OS) after the initial diagnosis. RESULTS: Of the 469 patients with HGG in our institution, less than 2% had PLS at the initial diagnosis. Most patients suffered from headache, diplopia, and dizziness. Pathological findings included 7 glioblastomas and 2 anaplastic astrocytomas. Seven of the 9 patients underwent CSF diversion. All patients were administered concurrent chemoradiotherapy (CCRT) with temozolomide, 89% of which started adjuvant temozolomide and 33% of which completed the six cycles of adjuvant temozolomide. The OS of patients with HGG and PLS was 8.7 months (range, 4-37), an extremely poor result compared to that of other studies. Also, the 1-year and 2-year OS rates were 44.4% and 16.7%, respectively. CONCLUSION: Diagnosis and treatment of HGG with PLS are challenging. Aggressive control of ICP followed by early initiation of standard CCRT seems to be helpful in improving symptoms. However, despite aggressive treatment, the prognosis is poor. A multicenter trial and research may be necessary to create a standardized protocol for this disease.

Isolated non-ascitic peritoneal carcinomatosis after robotic radical prostatectomy for prostate cancer: A case report.

Oncologic recurrence can occur after Robot-Assisted Radical Prostatectomy. Prostate cancer metastasizes often in bones, however the peritoneum is infrequently targeted. Even more, peritoneal dissemination without any other organ involved especially the bones is very rare, only few cases are reported. Through the available literature we discuss about the presumed seeding theory leading to this atypical location for prostatic metastases. Here we report a case of isolated non-ascitic prostatic peritoneal metastases most probably due to iatrogenic spillage during surgery.

Comparison of a coaxial versus non-coaxial liver biopsy technique in an oncological setting: diagnostic yield, complications and seeding risk.

OBJECTIVES: Percutaneous liver biopsy (PLB) poses specific challenges in oncological patients such as bleeding and tumour seeding. This study's aim was to compare a coaxial (C-PLB) and non-coaxial (NC-PLB) biopsy technique in terms of diagnostic yield, safety and seeding risk of image-guided PLB techniques in an oncological setting. METHODS: Local research committee approval was obtained for this single-site retrospective study. Patients who underwent a PLB between November 2011 and December 2017 were consecutively included. Medical records were reviewed to determine diagnostic yield and complications. Follow-up imaging was re-reviewed for seeding, defined as visible tumour deposits along the PLB track. Mann-Whitney U and chi-squared tests were performed to investigate differences between biopsy techniques in sample number, complications and seeding rate. RESULTS: In total, 741 patients (62 ± 13 years, 378 women) underwent 932 PLB (C-PLB 72.9% (679/932); NC-PLB 27.1% (253/932)). More tissue cores (p < 0.001) were obtained with C-PLB (median 4 cores; range 1-12) compared with NC-PLB (2 cores; range 1-4) and diagnostic yield was similar for both techniques (C-PLB 92.6% (629/679); NC-PLB 92.5% (234/253); p = 0.940). Complication rate (9.3%; 87/932) using C-PLB (8.2% (56/679)) was lower compared with NC-PLB (12.3% (31/253); p = 0.024). Major complications were uncommon (C-PLB 2.7% (18/679); NC-PLB 2.8% (7/253)); bleeding developed in 1.2% (11/932; C-PLB 1.2% (8/679); NC-PLB 1.2% (3/253)). Seeding was a rare event, occurring significantly less in C-PLB cases (C-PLB 1.3% (7/544); NC-PLB 3.1% (6/197); p = 0.021). CONCLUSIONS: C-PLB allows for high diagnostic tissue yield with a lower complication and seeding rate than a NC-PLB and should be the preferred method in an oncological setting. KEY POINTS: • A coaxial percutaneous liver biopsy achieves a significant higher number of cores and fewer complications than a non-coaxial biopsy technique. • The risk of tumour seeding is very low and is significantly lower using the coaxial biopsy technique. • In this study, a larger number of cores (median = 4) could be safely acquired using the coaxial technique, providing sufficient material for advanced molecular analysis.

Cutaneous port-site recurrence secondary to tumour seeding following implantation of an intraperitoneal chemotherapy access port for gastric cancer.

Intraperitoneal chemotherapy has shown promising results for the treatment of peritoneal carcinomatosis in gastric cancer. However, the implantation of an intraperitoneal chemotherapy port may be associated with catheter-related complications. The authors describe a case of cutaneous port-site recurrence secondary to tumour seeding from an intraperitoneal chemotherapy access port.

Perineal recurrence of prostate ductal adenocarcinoma after transperineal brachytherapy: a case report and literature review.

Perineal recurrence after brachytherapy is an exceedingly rare complication. Moreover, ductal adenocarcinoma is a rare histological variant of prostate cancer. Herein, we describe a case of perineal recurrence from ductal adenocarcinoma of prostate after low-dose-rate brachytherapy (LDR-BT) in a 65-year-old male patient. The patient had localized prostate cancer, for which he received LDR-BT; however, he experienced perineal recurrence 2 years after receiving LDR-BT. Surgical excision was attempted, but we were unable to remove the whole tumor, owing to invasion to surrounding tissue. Pathological examination of resected tumor showed ductal adenocarcinoma of the prostate. External beam radiation therapy and high-dose-rate brachytherapy (HDR-BT) were performed for residual tumor. Mild mediastinal lymph node swelling was observed during clinical course of the disease. Hence, androgen deprivation therapy was administered with abiraterone after radiation therapy, and prostate-specific antigen level decreased to undetectable level. Biochemical failure after transperineal brachytherapy for prostate cancer should be considered as a perineal recurrence.

Tumor Seeding after Robot-Assisted Radical Prostatectomy: Literature Review and Experience from a Single Institution.

PURPOSE: Seeding of tumor cells is a rare complication of minimally invasive surgery. We reviewed and improved current knowledge of prostate cancer seeding. MATERIALS AND METHODS: A literature review was performed using MEDLINE®, Embase® and the Cochrane Library, including cases of peritoneal and port site seeding reported after minimally invasive prostatectomy. In addition, after institutionally approved chart review a descriptive summary of a single institution experience on the topic is provided. RESULTS: The data from 9 reported cases of port site metastases from prostate cancer in the world literature are summarized along with 3 additional cases from our experience. Similarly, 5 cases of peritoneal seeding are reviewed from the literature with the addition of 3 more cases from our institution. Good long-term outcomes are achievable with multimodality and individualized regimens, including seeding directed treatments. CONCLUSIONS: Although no definitive recommendation can be made for treatment strategies for these patients, there is a need for awareness and further discussion of this atypical presentation.

No-Touch Multi-bipolar Radiofrequency Ablation for the Treatment of Subcapsular Hepatocellular Carcinoma ≤ 5 cm Not Puncturable via the Non-tumorous Liver Parenchyma.

PURPOSE: The percutaneous ablation of subcapsular hepatocellular carcinoma (S-HCC) may involve a risk of complications such as hemorrhage and tumor seeding, mainly linked to the direct tumor puncture often inevitable with mono-applicator ablation devices. The purpose of this study was to assess the efficacy and safety of no-touch multi-bipolar radiofrequency ablation (NTMBP-RFA) for the treatment of S-HCC ≤ 5 cm not puncturable via the non-tumorous liver parenchyma. MATERIALS AND METHODS: Between September 2007 and December 2014, 58 consecutive patients (median age: 63 years [46-86], nine females) with 59 S-HCC ≤ 5 cm (median diameter: 25 mm [10-50 mm]), not puncturable via the non-tumorous liver parenchyma, were treated with NTMBP-RFA. Response and follow-up were assessed by CT or MRI. Complications were graded using the Cardiovascular and Interventional Radiological Society of Europe classification. Overall local tumor progression (OLTP)-free survival was assessed using the Kaplan-Meier method. A Cox proportional model evaluated the factors associated with OLTP. Signs of peritoneal or parietal tumor seeding were noted during follow-up imaging studies. RESULTS: A complete ablation was achieved in 57/58 patients (98.3%) after one (n = 51) or two (n = 6) procedures. Three patients (5.2%) experienced complications (sepsis, cirrhosis decompensation; CIRSE grade 2 or 3). After a median follow-up period of 30.5 months [1-97], no patients had tumor seeding. The 1, 2 and 3-year OLTP-free survival rates were 98%, 94% and 91%, respectively. No factors were associated with OLTP. CONCLUSION: NTMBP-RFA is a safe and effective treatment for S-HCC not puncturable via the non-tumorous liver parenchyma.

Implantation Metastasis of Synovial Cell Sarcoma: Lessons Learned from a Mistake.

Implantation metastasis occurs when tumor seeds into a wound or tissue by a significant amount of viable tumor cells. Here we describe the case of a 30-year-old man suffering from pain and swelling of the foot, which was misdiagnosed as a bone cyst. Surgery was performed involving curettage followed by bone grafting. After surgical pathology, the exact diagnosis was revealed as the synovial sarcoma (SS) of the foot. Implantation metastasis of SS in the iliac region, the grafting site, occurred 9 months post-surgery. Although there are a few reports on implantation metastasis of other types of tumoral lesions, to the best of our knowledge, we describe seeding of this type of tumor for the first time. Similar to other studies, we recommend that tumor surgeries should be carried out in a special setting to prevent any spread to or contamination of other sites by the tumor.

Impact of Energy and Access Methods on Extrahepatic Tumor Spreading and the Ablation Zone: An Ex vivo Experiment Using a Subcapsular Tumor Model.

OBJECTIVE: To evaluate the impact of energy and access methods on extrahepatic tumor spreading and the ablation zone in an ex vivo subcapsular tumor mimic model with a risk of extrahepatic tumor spreading. MATERIALS AND METHODS: Forty-two tumor-mimics were created in bovine liver blocks by injecting a mixture of iodine contrast material just below the liver capsule. Radiofrequency (RF) ablations were performed using an electrode placed parallel or perpendicular to hepatic surface through the tumor mimic with low- and high-power protocols (groups 1 and 2, respectively). Computed tomography (CT) scans were performed before and after ablation. The presence of contrast leak on the hepatic surface on CT, size of ablation zone, and timing of the first roll-off and popping sound were compared between the groups. RESULTS: With parallel access, one contrast leak in group 1 (1/10, 10%) and nine in group 2 (9/10, 90%) (p < 0.001) were identified on post-ablation CT. With perpendicular access, six contrast leaks were identified in each group (6/11, 54.5%). The first roll-off and popping sound were significantly delayed in group 1 irrespective of the access method (p = 0.002). No statistical difference in the size of the ablation zone of the liver specimen was observed between the two groups (p = 0.247). CONCLUSION: Low-power RF ablation with parallel access is proposed to be effective and safe from extrahepatic tumor spreading in RF ablation of a solid hepatic tumor in the subcapsular location. Perpendicular placement of an electrode to the capsule is associated with a risk of extrahepatic tumor spreading regardless of the power applied.