A rare case of liver regenerative and non-neoplastic lesion resembling a well-differentiated hepatocellular carcinoma.

BACKGROUND: Nodular regenerative hyperplasia (NRH) is a rare disease that presents pathologically as diffuse hepatic nodules without fibrous septa. It is believed to be caused by vasculopathy against a background of various systemic diseases, such as hematologic, autoimmune, and drug-induced diseases, with various symptoms. In spite of the recent imaging advances, various atypical cases of nodular lesions are observed in daily clinical practice. Cases that do not completely meet these criteria are referred to as -like or -similar lesions in clinical situations, making it difficult to understand their pathogenesis. We present a case in which two hepatic nodular lesions were noted and difficult to differentiate from malignancy preoperatively. The lesions were laparoscopically resected and a pathological diagnosis with non-neoplastic liver regenerative nodules resembling NRH was made. CASE PRESENTATION: A 49-year-old man with no alcohol or drug intake and no past medical history was identified as having liver tumors on screening examination without any symptoms. Contrast-enhanced computed tomography (CT) showed two hepatic tumors; approximately 2-cm tumors at S7 and S8. Gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) revealed fat inclusions in their contents. Ethoxybenzyl (EOB) uptake was also observed during the hepatobiliary phase. Based on preoperative examinations, we suspected well-differentiated hepatocellular carcinoma (HCC) and performed laparoscopic S7/8 partial resection for these lesions. Macroscopically, the resected specimens showed a non-cirrhotic yellowish-cut surface containing brownish, ill-defined lesions with irregular borders. Microscopically, these lesions showed zonal necrosis, congestion, and aggregation of hemosiderin-laden macrophages around the central vein. In these areas, the fatty deposition of hepatocytes was lower than that in the surrounding background hepatocytes. Histopathologically, neither neoplastic nor hyperplastic lesions were observed, and he was diagnosed as regenerative hepatic change with centrilobular necrosis. CONCLUSIONS: Considering the pathological results, these lesions were thought to be a type of NRH-like lesion with possible hepatic vessel disorder. However, the lesion's cause and classification was difficult to determine. The accumulation of these regenerative changes accompanying fatty liver is needed to clarify the mechanism and its clinical significance.

Clinical significance of dual-energy dual-layer CT parameters in differentiating small-sized gastrointestinal stromal tumors from leiomyomas.

PURPOSE: Small gastrointestinal stromal tumors (GISTs) can generally have nonspecific CT findings similar to those with benign submucosal tumors of the stomach. The purpose of this study was to explore the potential dual-layer dual-energy CT (dlDECT) parameters to differentiate small-sized (≤ 4 cm) GISTs from leiomyomas of the stomach. MATERIALS AND METHODS: This retrospective study included 26 SMTs ≤ 4 cm in diameter with pathological confirmation of either GIST (n = 17) or leiomyoma (n = 9) from May 2018 to January 2022. All patients received contrast-enhanced CT. The normalized iodine concentration (NIC) and spectral slope (λHU) were compared between GIST and leiomyoma. Receiver-operating characteristic (ROC) curves were plotted and the areas under the curve (AUCs) were calculated to estimate the diagnostic performance of these markers for differentiating GISTs from leiomyomas. RESULTS: NIC was significantly higher in GIST than in leiomyoma in the portal (P = 0.0019) and delayed phases (P = 0.0011). λHU was significantly higher in GIST than in leiomyoma in the portal (P = 0.0006) and delayed phases (P = 0.0009). AUC of the ROC curves using NIC to differentiate between GIST and leiomyoma were 0.875 and 0.895 in the portal and delayed phase; using λHU, they were 0.918 and 0.902 in the portal and delayed phase. CONCLUSION: dlDECT parameters including NIC and λHU show promise as indicators for differentiating small-sized GISTs from leiomyomas.

Extracellular volume fraction determined by equilibrium contrast-enhanced computed tomography: correlation with histopathological findings in gastric cancer.

PURPOSE: To assess the relationship between histopathological features of gastric cancer and the extracellular volume fraction (ECV) measured by preoperative equilibrium contrast-enhanced computed tomography (CECT). MATERIALS AND METHODS: The study group consisted of 66 patients with surgically resected gastric adenocarcinoma who underwent preoperative multiphasic CECT. Tumor ECVs were calculated using region-of-interest measurements within the gastric cancer and aorta of each case on unenhanced and equilibrium-phase images. The relationship between the mean ECV values and clinicopathological parameters was examined by univariate analysis. Parameters showing a significant difference in the former test were further tested by linear regression and receiver operating characteristic (ROC) curve analyses. RESULTS: In the univariate analysis, the values of venous invasion (p = 0.0487) and tumor infiltration (INF) pattern (p < 0.0001) were significantly correlated with the tumor ECV. INF was significantly correlated (ß = 0.57, p < 0.0001) in the linear regression analysis. The tumor ECV showed better diagnostic accuracy for predicting INF (INFa/b vs INFc), and the area under the ROC curve value was 0.89. CONCLUSION: Tumor ECV determined by equilibrium CECT is significantly correlated with the pathological INF of gastric cancer.

Measurement of circumferential tumor extent of colorectal cancer on CT colonography: relation to clinicopathological features and patient prognosis after surgery.

PURPOSE: To examine the relationship between circumferential tumor extent of colorectal cancer (CRC) on CT colonography (CTC) and clinicopathological features including patient prognosis after surgery. MATERIALS AND METHODS: This retrospective study performed at our institution from January 2013 to December 2019 enrolled 195 consecutive patients (110 men, 85 women; mean age, 64.7 years) with CRC evaluated by contrast-enhanced CTC before surgery. The circumferential tumor extent rate (CER) was measured by CTC in virtual colon dissection (VCD) mode to examine the relation between the CER and clinicopathological features and patient prognosis. RESULTS: CER had association with tumor invasion depth (T), nodal involvement (N), distant metastasis (M), and stage. The Kruskal-Wallis tests showed significant difference for T, N and the stage (p < 0.0001, p = 0.0021 and p < 0.0001) and Wilcoxon rank sum test showed significant difference for M (p = 0.0015). According to the log-rank test, there were no significant differences in OS or DFS between patients with high and low CER. CONCLUSION: Circumferential tumor extent was significantly correlated with TNM categories and stage of CRC, but not with patient prognosis after surgery.

Factors of incomplete colonoscopy for stenosing colorectal cancer: CT colonography features.

PURPOSE: The purpose of this study was to examine the relation between computed tomography colonoscopy (CTC) features of colorectal cancer (CRC) and incomplete colonoscopy. MATERIALS AND METHODS: The subjects of this retrospective study consisted of 108 patients with advanced CRC (57 men, 51 women; age range, 32-87 years; median, 65 years) who underwent CTC. We compared local CTC features between the groups of complete (n = 74) and incomplete colonoscopy (n = 34). We performed a receiver operating characteristic (ROC) analysis to assess a diagnostic performance of CTC features to predict incomplete colonoscopy. RESULTS: The cross-sectional area of tumor and stenosis of complete colonoscopy group were significantly smaller and larger than those of incomplete colonoscopy group (p = 0.001 and < 0.001). Circumferential tumor extent rate (CER) showed significantly higher in the incomplete colonoscopy group than complete colonoscopy group (p < 0.001). In the ROC analysis, the cross-sectional area of stenosis showed AUC of 0.916, which was the best to predict incomplete colonoscopy. CONCLUSION: CTC features including larger cross-sectional area of tumor, smaller cross-sectional area of stenosis and 100% CER were significantly associated with incomplete colonoscopy for the patients with CRC.