Crystal structures of multidrug efflux transporters from Burkholderia pseudomallei suggest details of transport mechanism.

BpeB and BpeF are multidrug efflux transporters from Burkholderia pseudomallei that enable multidrug resistance. Here, we report the crystal structures of BpeB and BpeF at 2.94 Å and 3.0 Å resolution, respectively. BpeB was found as an asymmetric trimer, consistent with the widely-accepted functional rotation mechanism for this type of transporter. One of the monomers has a distinct structure that we interpret as an intermediate along this functional cycle. Additionally, a detergent molecule bound in a previously undescribed binding site provides insights into substrate translocation through the pathway. BpeF shares structural similarities with the crystal structure of OqxB from Klebsiella pneumoniae, where both are symmetric trimers composed of three "binding"-state monomers. The structures of BpeB and BpeF further our understanding of the functional mechanisms of transporters belonging to the HAE1-RND superfamily.

Structural basis of Irgb6 inactivation by Toxoplasma gondii through the phosphorylation of switch I.

Irgb6 is a priming immune-related GTPase (IRG) that counteracts Toxoplasma gondii. It is known to be recruited to the low virulent type II T. gondii parasitophorous vacuole (PV), initiating cell-autonomous immunity. However, the molecular mechanism by which immunity-related GTPases become inactivated after the parasite infection remains obscure. Here, we found that Thr95 of Irgb6 is prominently phosphorylated in response to low virulent type II T. gondii infection. We observed that a phosphomimetic T95D mutation in Irgb6 impaired its localization to the PV and exhibited reduced GTPase activity in vitro. Structural analysis unveiled an atypical conformation of nucleotide-free Irgb6-T95D, resulting from a conformational change in the G-domain that allosterically modified the PV membrane-binding interface. In silico docking corroborated the disruption of the physiological membrane binding site. These findings provide novel insights into a T. gondii-induced allosteric inactivation mechanism of Irgb6.

Action Quality Assessment Model Using Specialists' Gaze Location and Kinematics Data-Focusing on Evaluating Figure Skating Jumps.

Action quality assessment (AQA) tasks in computer vision evaluate action quality in videos, and they can be applied to sports for performance evaluation. A typical example of AQA is predicting the final score from a video that captures an entire figure skating program. However, no previous studies have predicted individual jump scores, which are of great interest to competitors because of the high weight of competition. Despite the presence of unnecessary information in figure skating videos, human specialists can focus and reduce information when they evaluate jumps. In this study, we clarified the eye movements of figure skating judges and skaters while evaluating jumps and proposed a prediction model for jump performance that utilized specialists' gaze location to reduce information. Kinematic features obtained from the tracking system were input into the model in addition to videos to improve accuracy. The results showed that skaters focused more on the face, whereas judges focused on the lower extremities. These gaze locations were applied to the model, which demonstrated the highest accuracy when utilizing both specialists' gaze locations. The model outperformed human predictions and the baseline model (RMSE:0.775), suggesting a combination of human specialist knowledge and machine capabilities could yield higher accuracy.

Improved Mortality, Morbidity, and Long-Term Outcome After Anatomical Hepatectomy With the Glissonean Pedicle Approach in Patients With Hepatocellular Carcinoma: 30 Years' Experience at a Single Institute.

OBJECTIVE: We evaluated the morbidity and mortality after anatomical hepatectomy with the Glissonean pedicle approach, and long-term outcomes in relation to the morbidity in patients with hepatocellular carcinoma (HCC). SUMMARY BACKGROUND DATA: The mortality, morbidity, and long-term outcomes were evaluated retrospectively. METHODS: A total of 1953 patients with HCC underwent various anatomical hepatectomies with the Glissonean pedicle approach between 1985 and 2014. The mortality (30-day and 90-day) and morbidity (Clavien-Dindo class Ilia or higher) were evaluated among six 5-year eras (1985-1989, 1990-1994, 1995-1999, 2000-2004, 2005-2009, 2010-2014). RESULTS: A total of 460 patients (24%) showed morbidity, and the overall 30-day and 90-day mortality rates were 1.8% and 3.3%, respectively. The 30-day (3.9%, 3.0%, 1.8%, 1.3%, 0.3%, 0.5%: P = 0.0074) and 90-day mortality (6.0%, 4.3%, 3.8%, 2.8%, 2.2%, 1.4%: P = 0.0445) significantly improved over the eras. Blood loss >2 L (odds ratio: 11.808, P = 0.0244) was an independent risk factor for 30-day mortality, and blood loss >2 L (odds ratio: 4.046, P = 0.0271) and bile leakage (odds ratio: 2.122, P = 0.0078) were independent risk factors for 90-day mortality on multivariate analysis. Morbidity was significant independent prognostic factors for overall survival (relative risk: 2.129, P < 0.0001) and recurrence-free survival (relative risk: 1.299, P < 0.0001) in patients with HCC. CONCLUSIONS: Anatomical hepatectomy with the Glissonean pedicle approach was achieved safely in patients with HCC. For more safety and longer survival, blood loss, bile leakage, and morbidity should be reduced. Longterm outcomes after anatomical hepatectomy with the Glissonean pedicle approach in patients with HCC have been improved over 30 years with gradually less mortality and morbidity due to decreases in blood loss >2 L and bile leakage.

Secondhand Smoke from a Veranda Spreading to Neighboring Households.

Secondhand smoke (SHS) caused by smoking on apartment verandas is a severe social problem in Japan. If someone smokes on a veranda, SHS drifts into other residents' rooms through their windows. Most non-smoking residents are annoyed by this, but they do not confront the person responsible. To study this situation, we burned cigarettes and measured the spread of SHS in terms of fine particle (PM2.5) concentrations. Cigarette smoke generated on a lower veranda spread to upper and horizontal neighboring verandas and into rooms through windows, reaching a maximum concentration of 139 µg/m3. The Health Promotion Act that was revised in 2018 and enacted in 2019-2020 requires all smokers to avoid producing SHS, even outdoors and at home. It is expected that combining the measurement of SHS from verandas to other verandas and rooms with the revised Health Promotion Act could create a national consensus on "no smoking on apartment verandas."

[Questionnaire Survey of Fukushima Daiichi Nuclear Power Plant Workers in 2016 on Knowledge and Anxiety About Radiation].

The results of a survey of radiation workers suggest that they are worried about the effects of radiation exposure on health, and approximately 30% of Fukushima Daiichi Nuclear Power Plant (FDNPP) workers have anxiety. This questionnaire survey reveals that the higher the frequency of radiation education, the higher the knowledge of radiation the workers will have, and that the higher the level of knowledge, the lower the anxiety. To reduce anxiety, it is important to increase knowledge about radiation through radiation education. However, even those workers who had radiation education several times still had anxiety. According to the Ordinance on the Prevention of Ionizing Radiation Hazards, the time spent on education about the effects of radiation on the human body is only about 30 minutes. This education is not enough to reduce anxiety. FDNPP workers needed more effective education to increase their knowledge and to reduce their anxiety.

Economic development and human ties in informal food waste recycling: A follow-up study in Da Nang, Vietnam.

This study examined the effects of economic development on the commercialised and non-commercialised segments of informal food waste recycling in Da Nang City, Vietnam. Food waste was collected from the urban centre and used as pig feed in swine farms in suburban areas. The commercialised and non-commercialised segments of this system have evolved differently over time. During our observation period of 2011-2016, swine farmers became concerned about economic efficiency, which affected the manner in which they used food waste. By 2016, more farmers had begun to use food waste brokers instead of collecting food waste themselves so that they could concentrate on rearing pigs. The price of food waste remained low, reflecting the farmers' need for low-cost feeding. This resulted in the closure of commercialised transactions between households and waste collectors amid increased household income. Instead, non-commercialised transactions supported by human ties became the main mode of household participation in food waste recycling . Our findings can guide the use of different elements in this informal recycling system within the framework of a formalised recycling system implemented by the government.

Screening of BCOR-CCNB3 sarcoma using immunohistochemistry for CCNB3: A clinicopathological report of three pediatric cases.

BCOR-CCNB3 sarcoma is a recently recognized tumor morphologically and clinically simulating Ewing sarcoma. We herein retrospectively collected clinicopathologic data on BCOR-CCNB3 sarcoma in the Kyoto University Hospital over the last 10 years. Three (20%) bone sarcomas were revealed to be diffusely positive for CCNB3 immunohistochemistry among 15 pediatric cases of undifferentiated sarcoma morphologically similar to Ewing sarcoma, while the other cases showed completely negative staining. The three patients with immunohistochemically CCNB3-positive tumors were all male, aged between 11 and 17, and confirmed to have the BCOR-CCNB3 fusion transcript by RT-PCR. Radiologically, all cases had well-demarcated solid masses with bone destruction. Although the tumors were basically small round cell tumors, less monomorphic histological patterns such as short spindle cells, a myxoid matrix, and hemangiopericytoma-like pattern were also observed in both biopsy and resected specimens. Two patients achieved a complete response after chemotherapy for Ewing sarcoma and osteosarcoma, respectively. These results demonstrated that the application of CCNB3 immunostaining was useful for differentiating BCOR-CCNB3 from a group of 'Ewing-like sarcomas' and may contribute to the evaluation of treatment strategies for bone sarcomas.

Eye size recognition of self and others among people with self-face dissatisfaction.

Previous studies have shown that individuals visually recognize their eye size as larger than the actual. However, it is unclear whether this cognitive tendency occurs in people with high self-face dissatisfaction. Therefore, this study aimed to investigate whether the cognitive size of one's own and others' eyes differs according to the degree of self-face dissatisfaction. Participants comprised 32 college students (5 males, 27 females; age: 21.3 ± 2.11) who completed the Face Dissatisfaction Scale (FDS) and a face recognition memory task. The task was to choose whether their or their friends' eyes in the face photos with changed eye size were larger or smaller than their actual eye size. The cognitively equivalent eye size to the actual one was estimated from a psychophysical function. We conducted a correlation analysis of the total scores on the FDS and the point of subjective equality (PSE) of eye size. We found a high negative correlation between the FDS and the PSE of own eye size. There was also a high positive correlation between the FDS and the PSE for all others' faces. Thus, high self-face dissatisfaction is differentially associated with cognitive distortions of the face, depending on whether it is self or other.

The Outcome of Salvage Liver Transplantation and Liver Resection for Recurrent Hepatocellular Carcinoma Using the 5-5-500 Rule, Japanese Extended Liver Transplantation Criteria for Hepatocellular Carcinoma.

BACKGROUND: Liver transplantation (LT) for hepatocellular carcinoma (HCC) is limited to Child-Pugh class C patients according to the Japanese HCC treatment algorithm. However, extended criteria of LT for HCC, known as the 5-5-500 rule, were published in 2019. Hepatocellular carcinoma reportedly has a high recurrence rate after primary treatment. We hypothesized that the outcome of recurrent HCC would be improved if the 5-5-500 rule were adopted for patients with recurrent HCC. We, therefore, analyzed the outcomes of surgical treatment (liver resection [LR] and LT) for recurrent HCC using the 5-5-500 rule in our institute. METHODS: Fifty-two patients younger than 70 years of age received surgical treatment for recurrent HCC using our institute's 5-5-500 rule from 2010 to 2019. We divided these patients into the LR and LT groups in the first study. The 10-year overall survival and re-recurrence-free survival were analyzed. The second study analyzed the risk factors of re-recurrence after surgical treatment for recurrent HCC. RESULTS: In the first study, the background characteristics of the 2 groups (LR and LT) showed no significant difference, except for age and Child-Pugh classification. There was no significant difference in the overall survival between groups (P = .35), but the re-recurrence-free survival in the LR group was significantly shorter than that in the LT group (P < .01). In the second study, the male sex and LR were risk factors of re-recurrence after surgical treatment for recurrent HCC. Child-Pugh's class did not contribute to re-recurrence. CONCLUSIONS: To improve the outcomes of recurrent HCC, LT is the better choice, regardless of the Child-Pugh class.

Left hepatectomy with suprahepatic inferior vena cava resection and reconstruction under veno-arterial extracorporeal membrane oxygenation for intrahepatic cholangiocarcinoma: a case report.

BACKGROUND: Curative surgery is the most effective treatment for intrahepatic cholangiocarcinoma (ICC). When an ICC involves the suprahepatic inferior vena cava (IVC), hepatectomy with suprahepatic IVC resection and reconstruction is challenging. For reconstruction of the suprahepatic IVC, total hepatic vascular exclusion (THVE), veno-venous bypass, and/or in situ hypothermic portal perfusion are required, but mortality and morbidity remain high. CASE PRESENTATION: We present a 73-year-old woman with mass-forming ICC which invaded the suprahepatic IVC and middle hepatic vein. Left hepatectomy, suprahepatic IVC resection, and reconstruction with an artificial graft were successfully performed during veno-arterial extracorporeal membrane oxygenation (V-A ECMO) to maintain blood pressure. While clamping the IVC diagonally, the right hepatic vein confluence could be preserved. No congestion in the right liver was seen; therefore, there was no requirement for the Pringle maneuver or THVE during reconstruction. No morbidity or mortality was seen after surgery. CONCLUSIONS: Hepatectomy with suprahepatic IVC resection and reconstruction under V-A ECMO can be performed safely. When an ICC invades the suprahepatic IVC, V-A ECMO during resection and reconstruction of the suprahepatic IVC with an artificial graft is recommended as one of the options.

Intrahepatic Cholangiocarcinoma With Neither Intrahepatic Metastasis Nor Lymph Node Metastasis Is the Optimal Indication for Hepatectomy With Adjuvant Therapy.

Background/Aim: The optimal indication of hepatectomy with adjuvant therapy for intrahepatic cholangiocarcinoma (ICC) has not been evaluated in detail. Patients and Methods: We retrospectively studied 224 patients with ICC who underwent hepatectomy between 2000 and 2019. Prognostic factors for overall survival (OS) were evaluated by univariate and multivariate analysis. A total of 127 patients were treated with adjuvant therapy (62 patients with chemotherapy and 65 patients with immunotherapy) after hepatectomy, and 97 patients were treated with hepatectomy alone. Results: Intrahepatic metastasis (IM), lymph node metastasis (LNM) of ICC, adjuvant chemotherapy, and adjuvant immunotherapy were significant prognostic factors for OS on multivariate analysis. In 127 patients with neither IM nor LNM, the 5-year OS rate was significantly higher in 36 patients with adjuvant chemotherapy (81%) and in 34 patients with adjuvant immunotherapy (68%) than in 57 patients with hepatectomy alone (45%). Conclusion: The absence of IM or LNM is the optimal indication for hepatectomy with adjuvant therapy in patients with ICC.

Contribution of radiation education to anxiety reduction among Fukushima Daiichi Nuclear Power Plant workers: a cross sectional study using a text mining method.

The purpose of this study is to investigate the frequency of education, knowledge of radiation and workplace anxiety of Fukushima Daiichi Nuclear Power Plant (FDNPP) workers and to analyze what type of words are used for anxiety with a text mining method. An original questionnaire survey was given to FDNPP workers, and a text mining method was used to extract information from free-entry fields. The questionnaires were collected from 1135 workers (response rate: 70.8%). It was found that when workers receive education on radiation, the increased knowledge helps to reduce their anxiety. Among the 1135 workers, 92 of 127 completed the free-entry field with valid entries. Seventy-one words were extracted by the text mining method. The words used differed depending on the degree of anxiety. The text mining method revealed information about the presence or absence of radiation anxiety and the subjects' working environment and background.

Autoimmune Factor V Deficiency That Took 16 Years to Diagnose due to Pseudodeficiency of Multiple Coagulation Factors.

A 70-year-old man presented to our hospital with intramuscular hemorrhage in the right thigh. He had exhibited a tendency to bleed for the last 16 years and had visited several medical institutions, but no diagnosis had been made. Since the risk of sudden bleeding was assumed to be high due to his age, we decided to examine him in our department. A coagulation abnormality with prothrombin time-international normalized ratio (PT-INR) of 4.5 and activated partial thromboplastin time (aPTT) of 99.6 seconds was observed, but the platelet count, fibrinogen, and PIVKAII were within normal limits. Coagulation activities of factor V, VII, VIII, IX, X, XI, XII, and XIII were all reduced. Anti-factor VIII and IX antibodies which were measured by the Bethesda method, lupus anti-coagulant (diluted Russell snake venom time method) and anti-cardiolipin antibody were also positive. The results of these tests were comparable to those undertaken 15 years ago when they were scrutinized at the university hospital. We suspected the presence of anti-factor V antibodies because there was a dissociation between the thrombotest values measured and those calculated from the PT-INR. Moreover, cross-mixing test showed an immediate inhibitor pattern. Subsequently, factor V antibodies were confirmed by the immunoblot method and the diagnosis of autoimmune factor V deficiency was made. When factor V, which is downstream of the coagulation cascade, is inhibited, coagulation test using the one-stage clotting method shows a pseudolow value. Therefore, extensive abnormalities of coagulation factor activity and inhibitor assay should be interpreted with caution, and the presence of a high titer of factor V inhibitor should be considered.

Hereditary Apolipoprotein A-1 Amyloidosis With Glu34Lys Mutation Treated by Liver Transplantation: A Case Report.

Hereditary apolipoprotein A-1 (ApoA-1) amyloidosis is a rare disease characterized by progressive deposition of amyloid fibrils in the kidney, heart, and liver. We observed a 45-year-old male patient with liver failure. Liver dysfunction was detected at 30 years of age during an annual health check-up. At 35 years of age, renal dysfunction was also found. At 40 years of age, the pathologic findings of the liver revealed amyloid deposition. A testis biopsy specimen taken at 42 years of age to identify the cause of male infertility showed amyloid accumulation. At 43 years of age, the amyloid results and genetic profile led to a definitive diagnosis of hereditary ApoA-1 amyloidosis caused by Glu34Lys mutation. A family history was absent. Liver failure showed Budd-Chiari-like formation, including enlargement of the caudate lobe and liver congestion. Although the patient showed end-stage liver cirrhosis and renal failure, only liver transplant was performed considering the burden for a living donor. The enlarged liver (4.9 kg) showed amyloid deposition in parenchyma and the space of Disse. Amyloid also accumulated in the giant spleen. The APOA1 mutation Glu34Lys is extremely rare, and in this case hepatic failure was successfully treated by liver transplant to both replace organ function and reduce production of the amyloidogenic ApoA-1-variant protein. Careful observation for reaccumulation of amyloidosis in the organ is required.

Incidence of intracranial arterial dissection in non-emergency outpatients complaining of headache: preliminary investigation with MRI/MRA examinations.

PURPOSE: Headache is recognized as one of the specific signs of intracranial arterial dissection (ICrAD). We clarified the incidence of ICrAD in non-emergency outpatients complaining of headache and the nature of headache observed in case of ICrAD. PATIENT POPULATION AND METHODS: Consecutive non-emergency outpatients coming to the neurological and neurosurgical departments and who underwent MRI and MRA examinations were included in this study. The diagnosis of ICrAD was made when patients met the following two conditions: (1) pearl-and-string sign, pearl sign, or string sign on MRA, and (2) high arterial wall signal on T1 images or intimal flap on T2 images. If possible, cerebral angiography and/or black blood MRI and/or surface-image MRI was also performed in cases meeting these criteria. RESULTS: (1) Headache group (172 patients): severe headache was seen in five patients and headache of sudden onset in three. Arterial dissection was diagnosed in eight patients (4.7%, including seven cases of asymptomatic vertebral dissection and one of basilar dissection). The headache noted in most cases of ICrAD was similar to that experienced in daily life. (2) Non-headache group (201 patients): complaints included vertigo/dizziness in 52 patients, gait disturbance in 28, weakness of the arm or leg in 20, and limb numbness in 18, syncope attack in 14, and others in 69. Arterial dissection was diagnosed in six patients (3.0%, including one case of asymptomatic basilar and two of vertebral artery dissection, symptomatic two vertebral and one basilar dissection). CONCLUSION: We obtained no evidence of significant difference in the incidence of ICrAD in non-emergency outpatients with (4.7%) and without headache (3.0%). The nature of the headache in the cases of ICrAD was similar to that experienced in daily life. ICrAD with nonspecific headache is more common than previously thought.

Using "Enzan No Metsuke" (Gazing at the Far Mountain) as a Visual Search Strategy in Kendo.

In Kendo (Japanese fencing), "Enzan no Metsuke" is an important Waza (technique) that is applied by expert Kendo fighters. It involves looking at the opponent's eyes with "a gaze toward the far mountain," taking in not only the opponent's face but also his or her whole body. Over the last few decades, a considerable number of studies on visual search behaviors in sport have been conducted. Yet, there are few articles that examine visual search behaviors in combat sports, such as martial arts. This study aimed to analyze the visual search strategies used by expert Kendo fighters through sparring practices to discuss what "Enzan no Metsuke" is under experimental, but natural (in situ), conditions. Ten experts, 10 novices, and one Shihan (a master of Kendo) participated in this study. The fighters wore a mobile eye tracker and faced a real opponent. They were instructed to do the following in five different sessions: prepare themselves, practice their offense and defense techniques, and fight in a real Shiai (match). The results indicated differences in the visual search strategies between the Shihan, experts, and novices. The Shihan and experts fixated on their opponent's eyes or head region most of the time and adopted a visual search strategy involving fewer fixations of longer duration. Conversely, novices set their eyes mainly on the opponent's Shinai (sword). Only the Shihan always looked at the opponent's eyes, even during the preparation, offense, and defense sessions. Shihan and experts set their "visual pivot" on the opponent's eyes quietly, even when the opponent tried to attack with the Shinai. Novices, however, moved their eyes up and down based on the influence of their opponent's movements. As these results indicate, novices tried to search for detailed information about their opponent and processed visual information depending on their focal vision, whereas Shihan and experts absorbed information not from their opponent's eyes but from their entire body by utilizing their peripheral vision; this means that Shihan and experts could see an opening or opportunity and react instantaneously by using "Enzan no Metsuke."

Debulking of giant liver hemangiomas with severe symptoms: a case report.

BACKGROUND: There are no previous reports of debulking of giant liver hemangioma. This report describes our experience with debulking surgery for a patient with bilateral giant liver hemangiomas with severe symptoms. CASE PRESENTATION: We present a case of symptomatic giant liver hemangioma in a 41-year-old woman. She presented with abdominal pain and fullness at a local hospital and underwent trans-arterial embolization (TAE). TAE was not effective, and she was not able to walk a long distance. Giant liver hemangiomas, 30 cm and 15 cm in diameter, were located in the right liver and in the left lateral section, respectively, and normal liver parenchyma with tiny liver hemangiomas was present in segment 4. The liver function was normal. However, right hemi-hepatectomy with left lateral sectionectomy was considered to be risky according to the 3DCT volumetry. Therefore, we performed right hemi-hepatectomy in order to reduce her symptoms. The postoperative course was uneventful, and she was discharged on the 14th day after surgery. The abdominal fullness and abdominal pain disappeared immediately after surgery. The hemangiomas in the remnant liver, 15 cm in diameter, showed no change, and she is well without symptoms 7 years after surgery. CONCLUSIONS: Debulking surgery is one of the options for bilateral giant liver hemangiomas with severe symptoms.

A patient with post-Fontan operation underwent left hepatectomy and caudate lobectomy for hepatocellular carcinoma: a case report.

BACKGROUND: The Fontan procedure has been widely accepted for children with single ventricle physiology and guarantees survival rates of approximately 80% at age 20 years. However, there have been cases of Fontan-associated liver disease (FALD) caused due to congestion, along with recent reports of the development of hepatocellular carcinoma (HCC) in younger patients with FALD. The literature consists of only five previous case reports of patients who underwent hepatectomy for HCC due to poorer cardiac function and liver cirrhosis caused due to congestion. CASE PRESENTATION: The patient was a 37-year-old woman who presented with epigastralgia. Computed tomography (CT) revealed a liver tumor, 8 cm in diameter, in the caudate lobe. Liver damage was A, with an indocyanine green retention rate of 6% at 15 min. The levels of alpha-fetoprotein (AFP) and protein induced by vitamin K antagonists-II (PIVKA-II) were elevated to 81,663 ng/ml (normal < 10 ng/ml) and 238 mAU/ml (normal < 40 mAU/ml), respectively. Left ventricular ejection fraction was 56%, and central venous pressure (CVP) was 12 mmHg. Left hepatectomy and caudate lobe resection were successfully performed in the reverse Trendelenburg position which reduced the CVP. The total operation duration was 450 min, with a total blood loss of 3200 ml. The patient's postoperative course was uneventful, and she is still alive 16 months after surgery. CONCLUSIONS: First left hepatectomy with caudate lobectomy during reverse Trendelenburg position which reduced the CVP was performed in a patient with HCC and FALD.

Hepatocellular carcinoma with ring calcification mimicking hydatid disease: a case report.

BACKGROUND: Ring calcification in hepatocellular carcinoma is extremely rare. Untreated hepatocellular carcinoma occasionally includes calcified lesions. Here, we report a case of ring-calcified hepatocellular carcinoma. CASE PRESENTATION: A 60-year-old man with a hepatic tumor was referred to Tokyo Women's Medical University Hospital. He had a history of chronic hepatitis C. Computed tomography showed a liver tumor 20 mm in diameter in segment 6 of the Couinaud classification, with ring calcification. Based on this uncommon imaging presentation and the patient's past exposure to the definitive hosts of Echinococcus multilocularis, he was preoperatively diagnosed with echinococcosis. Partial hepatectomy was performed as a radical treatment for echinococcosis. A final diagnosis of hepatocellular carcinoma was confirmed based on pathological findings. The patient was discharged uneventfully. CONCLUSION: The presentation of an extremely rare hepatocellular carcinoma with ring calcification may be disguised as hydatid disease.