Close relationships between neck and upper-back stiffness and transverse cervical artery flow velocity.

PURPOSE: Neck and upper-back stiffness is encountered in daily life, with symptoms appearing as dullness or aches predominantly in the trapezius muscle (TM). Our previous study demonstrated that TM hardness as measured with a muscle hardness meter correlates well with transverse cervical artery (TCA) flow supplying the TM. Muscle hardness meters, however, cannot measure hardness in the TM alone. Meanwhile, recent advances in ultrasound elastography have enabled the evaluation of localized hardness in targeted tissues. The present study, therefore, aimed to clarify the relationship between TM hardness as measured by elastography and TCA hemodynamics as measured on Doppler sonography, with reference to daily symptoms of upper-back stiffness. METHODS: The study population comprised 66 healthy young adults (32 males, 34 females; mean age, 21 ± 1 years). Relationships were evaluated between TM hardness as a negative correlate of strain ratio from elastography and TCA hemodynamics on Doppler sonography. Hemodynamics in the TCA were evaluated according to the frequency of neck and upper-back stiffness. RESULTS: TM strain ratio correlated with peak systolic velocity (PSV) in the TCA (r = 0.273, p = 0.036), particularly in symptomatic subjects (r = 0.417, p = 0.022). PSV in the TCA decreased with increasing frequency of daily symptoms (p = 0.045). CONCLUSION: TCA hemodynamics correlated with muscle hardness when evaluating localized TM hardness. This relationship and low PSV in the TCA were evident in symptomatic subjects. These results suggest that PSV in the TCA is associated with neck and upper-back stiffness.

Sex-dependent impact of a short rest after lunch on hemodynamics as assessed by Doppler sonography.

PURPOSE: Taking a short rest after lunch suppresses increases in blood flow to the digestive organs and maintains blood flow to the brain in the afternoon, possibly providing beneficial effects in preventing post-prandial drowsiness. The present study investigated sex-dependent influences on changes in hemodynamics produced by taking a short rest after lunch. METHODS: Subjects comprised 20 healthy young adults (10 men, 10 women; mean age 21 ± 1 years). Doppler sonography was performed to measure blood flow in the superior mesenteric artery (SMA) and common carotid artery (CCA) before and after lunch every hour on each day, with and without a 15-min rest with eyes closed after lunch. Blood pressure and heart rate (HR) were also measured. RESULTS: For both men and women, peak systolic velocity (PSV) in the SMA was suppressed by taking a rest. PSV in the CCA in men was increased at 0.5 h after lunch in the resting condition but was decreased in the non-resting condition (median 109%, interquartile range [IQR] 102-120% vs. median 98%, IQR 90-107%; P = 0.037). No such differences were observed in women. Although post-prandial increases in HR were observed in women, a similar increase was only found for men in the resting condition. CONCLUSION: An increase in CCA blood flow was observed only in men. The present study suggests that a short rest after lunch could better promote the maintenance of blood flow to the brain in men than in women.

A rad50 germline mutation induces tumorigenesis and ataxia-telangiectasia phenotype in a transparent medaka model.

The MRE11A-RAD50-NBS1 complex activates the ataxia-telangiectasia mutated (ATM) pathway and plays a central role in genome homeostasis. The association of RAD50 mutations with disease remains unclear; hence, we adopted a medaka rad50 mutant to demonstrate the significance of RAD50 mutation in pathogenesis using the medaka as an experimental animal. A 2-base pair deletion in the rad50 gene was introduced into transparent STIII medaka using the CRISPR/Cas9 system. The mutant was analyzed histologically for tumorigenicity and hindbrain quality, as well as for swimming behavior, to compare with existing ATM-, MRE11A-, and NBS1-mutation-related pathology. Our results revealed that the medaka rad50 mutation concurrently reproduced tumorigenesis (8 out of 10 rad50Δ2/+ medaka), had a decrease in median survival time (65.7 ± 1.1 weeks in control vs. 54.2 ± 2.6 weeks in rad50Δ2/+ medaka, p = 0.001, Welch's t-test), exhibited semi-lethality in rad50Δ2/Δ2 medaka and most of the major ataxia-telangiectasia phenotypes, including ataxia (rheotaxis ability was lower in rad50Δ2/+ medaka than in the control, Mann-Whitney U test, p < 0.05), and telangiectasia (6 out of 10 rad50Δ2/+ medaka). The fish model may aid in further understanding the tumorigenesis and phenotype of ataxia-telangiectasia-related RAD50 germline mutations and in developing novel therapeutic strategies against RAD50 molecular disorders.

Plasma free amino acid profiles are associated with serum high molecular weight adiponectin levels in Japanese medical check-up population without type 2 diabetes mellitus.

To prevent the progression of type 2 diabetes mellitus (T2DM), early detection and intervention are important. Several studies have already shown that the serum adiponectin level could be useful for evaluating the future risk of T2DM. Recently, plasma free amino acid (PFAA) concentrations have also emerged as potential biomarkers that predict the future onset of T2DM. In this study, we aimed to further characterise PFAA profiles by elucidating the association with the serum high molecular weight (HMW) adiponectin level in this cross-sectional study. A total of 1000 Japanese subjects who underwent medical check-ups were enrolled, and their plasma concentrations of 21 amino acids and clinical parameters were measured. The subjects without T2DM were divided into quartiles (Q1-4) by serum HMW adiponectin level, and the association with between PFAA concentrations was analysed. Concentrations of glutamate, alanine, proline, tyrosine, histidine, methionine, lysine, branched-chain amino acids (BCAAs) and tryptophan varied significantly according to the adiponectin quartile. Furthermore, serum adiponectin levels showed significant inverse correlations with these amino acids. The change in the PFAA profile in the group with the lowest adiponectin concentrations (Q1) was similar to that of T2DM patients. Although both adiponectin levels and PFAA concentrations are known to be altered by the accumulation of visceral fat and insulin resistance, the levels of glutamate, BCAA, lysine and tryptophan remain significantly associated with adiponectin level after adjustment for age, body mass index and homeostasis model assessment of insulin resistance, showing the direct association between PFAA concentrations and the serum HMW adiponectin level. Registration number: University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) UMIN000029920, registered on Nov 13th 2017 (prospectively registered).

Microsatellite instability in the high-grade dysplasia component of duodenal adenoma is associated with progression to adenocarcinoma.

PURPOSE: We examined the microsatellite instability of duodenal tumors to evaluate their molecular features associated with the adenoma-carcinoma sequence. METHODS: Fifty-two non-ampullary duodenal epithelial tumors collected by endoscopic mucosal resection or surgical resection were studied. When a tumor had two or more dysplasia grades, the highest grade was considered. Representative areas were macro-dissected and subjected to a microsatellite instability analysis and immunohistochemical staining. RESULTS: The 52 tumors were classified as either adenoma with low-grade dysplasia (n = 18), adenoma with high-grade dysplasia (n = 20), or adenocarcinomas (n = 14). Among these, 3 adenocarcinoma cases showed microsatellite instability and the remaining 49 tumors showed microsatellite stability. Of the 14 adenocarcinoma cases, 3 contained both high-grade dysplasia and adenocarcinoma components, and 11 contained only the adenocarcinoma component. Interestingly, all three adenocarcinoma + high-grade dysplasia cases were microsatellite instability-high in both the adenocarcinoma and high-grade dysplasia components. Immunohistochemical staining of mismatch repair proteins showed mismatch repair deficiency in three microsatellite instability-high adenocarcinoma + high-grade dysplasia cases. CONCLUSIONS: Only adenocarcinoma cases with high-grade dysplasia components were microsatellite instability-high (in both the adenocarcinoma and high-grade dysplasia components). This suggests that microsatellite instability in the high-grade dysplasia component of duodenal adenoma is associated with progression to adenocarcinoma.

Can Individuals with Suboptimal Antibody Responses to Conventional Antiviral Vaccines Acquire Adequate Antibodies from SARS-CoV-2 mRNA Vaccination?

In Japan, healthcare workers (HCWs) are vaccinated against measles, rubella, chickenpox, mumps, and hepatitis B to prevent nosocomial infection; however, some do not produce sufficient antibodies ("suboptimal responders"). This study compared immune responses to a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 mRNA) vaccine among HCWs with normal and suboptimal responses to conventional vaccines. In this prospective cohort study, 50 HCWs received two doses of BNT162b2 mRNA vaccine 3 weeks apart. SARS-CoV-2 anti-spike antibodies were measured 11 times, starting before the first vaccination and ending 5 months after the second vaccination. Antibody titers of four suboptimal and 46 normal responders were compared. SARS-CoV-2 neutralizing antibody activity was measured twice in suboptimal responders, 1 week/1 month and 5 months after the second vaccination. The SARS-CoV-2 anti-spike antibody was detectable in the samples from suboptimal and normal responders at each timepoint after vaccination. Suboptimal responders exhibited SARS-CoV-2 neutralizing antibody activity 1 week/1 month as well as 5 months after the second vaccination; however, activity was slightly reduced at 5 months. Our findings show that suboptimal responders do acquire adequate SARS-CoV-2 anti-spike and SARS-CoV-2 neutralizing antibodies from vaccination to prevent SARS-CoV-2. SARS-CoV-2 mRNA vaccines should thus be recommended for both normal and suboptimal responders to conventional vaccines.

A case of multiple abscesses caused by Nocardia farcinica rapidly diagnosed by MALDI-TOF MS.

Identifying Nocardia species in routine tests is often difficult owing to its culture time. We report a case of nocardiosis characterized by multiple abscesses of disseminated disease. A man in his 50 's presented with inflammation on the left buttock and right lower leg. Nocardia farcinica was isolated from the abscess on his buttock and confirmed using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Radiological assessment revealed multiple abscesses in his brain, left lung, and right thigh. He was successfully treated with antibiotics. Accurate species identification by MALDI-TOF MS aids in the optimal treatment of nocardiosis.

Possible effects of short rest after lunch on hemodynamics in the afternoon.

PURPOSE: Drowsiness is often experienced in the afternoon after lunch. Decreases in blood flow to the brain secondary to increases in blood flow to the digestive organs after food intake could represent an underlying cause. As various beneficial effects of short rests on mental activities have been reported, the present study investigated hemodynamics using Doppler sonography of the common carotid artery (CCA) and superior mesenteric artery (SMA) after lunch, comparing resting and non-resting cases. METHODS: Subjects comprised 24 healthy young adults (10 men, 14 women; mean age 22 ± 1 years). Sonography was performed to measure blood flow before and after lunch on each day, with and without a 15-min lying rest with eyes closed after lunch in each subject. RESULTS: The timing of the peak velocity-time integral in the SMA in resting cases was delayed to 1.5 h after lunch compared to 0.5 h in non-resting cases. Although end-diastolic velocity in the CCA decreased after lunch, this decrease was suppressed in resting cases compared to non-resting cases even 4.5 h after lunch (median 96%, interquartile range [IQR] 83-102% vs. median 87%, IQR 77-92%; P = 0.037). Mean velocity (MV) in the CCA maintained unchanged after lunch in resting cases (P = 0.318), whereas non-resting cases showed decreased MV after lunch (P < 0.001). CONCLUSION: These findings suggest that a short lying rest with eyes closed suppresses increases in blood flow to the digestive organ and maintains blood flow to the brain after lunch. These hemodynamic changes might help explain the benefits of afternoon rests.

Sonographically Measured Adipose Tissue Thickness Correlates with Laboratory Test Abnormalities Reflecting Metabolic State in Elderly Women.

Background: Accumulation of adipose tissue progresses to metabolic diseases. Sonography is a convenient modality for measuring the thickness of adipose tissue. The present study aimed to clarify the site of adipose tissue thickness that correlated best with laboratory test values reflecting metabolic abnormalities. Methods: Subjects comprised 37 elderly women with metabolic diseases or an almost healthy state (median age, 71 years; interquartile range, 62-78 years). Abdominal visceral adipose tissue (VAT), subcutaneous adipose tissue, peritoneal adipose tissue, perirenal adipose tissue, and epicardial adipose tissue (EAT) thicknesses were measured. Correlations were evaluated between laboratory test values and these adipose tissue thicknesses. Results: VAT thickness measured at the level of the umbilicus correlated positively with values of triglycerides (TGs) (r = 0.593, P = 0.0009) and hemoglobin A1c (r = 0.490, P = 0.0081) and negatively with the value of high-density lipoprotein cholesterol (r = -0.521, P = 0.0045), even after adjusting for body mass index. Significant positive correlations were also found between EAT thickness and TGs (r = 0.542, P = 0.0029). Conclusions: Among the adipose tissue thicknesses measured at several sites by sonography, VAT thickness correlated most closely with laboratory test values representing metabolic abnormalities in elderly women.

First description of Lachnoanaerobaculum orale as a possible cause of human bacteremia.

Lachnoanaerobaculum spp. is an obligate anaerobic, gram-positive, spore-forming, rod-shaped bacillus. Here, we report the first known case of bacteremia due to L. orale, which was detected in a patient with acute lymphoblastic leukemia. A 69-year-old man developed neutropenic fever with severe stomatitis during chemotherapy for leukemia. The bacteria strain isolated from blood culture was successfully identified as L. orale via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Susceptibility testing revealed that the strains showed low minimum inhibitory concentrations (MICs) of beta-lactams, clindamycin, and metronidazole, but higher MICs of fluoroquinolones. The present case study indicates that Lachnoanaerobaculum can be a cause of human infection, including bloodstream infection.

Establishing an internal quality control method for the stable extraction of nucleic acids of severe acute respiratory syndrome coronavirus 2 and RT-PCR-based detection.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the coronavirus disease 2019 (COVID-19), is detected using real-time RT-PCR. However, there are limitations pertaining to quality control, particularly with respect to establishing quality control measures for extraction of viral nucleic acids. Here, we investigated the quality control measures for the various processes using an extrinsic quality control substance and quality control charts. METHODS: An extrinsic quality control substance was added to the sample, and then, real-time RT-PCR was performed. Samples with negative test results and the corresponding data were analyzed; a quality control chart was created and examined. RESULTS: Data analysis and the quality control charts indicated that SARS-CoV-2 could be reliably detected using real-time RT-PCR, even when different nucleic acid extraction methods were used or when different technicians were employed. CONCLUSION: With the use of quality control substances, it is possible to achieve quality control throughout the process-from nucleic acid extraction to nucleic acid detection-even upon using varying extraction methods. Further, generating quality control charts would guarantee the stable detection of SARS-CoV-2.

Risk Factors for and the Prognostic Impact of Pericardial Effusion after Allogeneic Hematopoietic Stem Cell Transplantation.

Pericardial effusion (PE) is a rare complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Although the mechanisms underlying the onset of PE remain unclear, patients with PE after allo-HSCT have poor clinical outcomes. However, the prognostic impact of PE remains controversial, and risk factors have varied among studies. Therefore, we examined contributing as well as prognostic factors for PE. We retrospectively examined 243 patients who underwent allo-HSCT at the Faculty of Medicine, Kagawa University and Takamatsu Red Cross Hospital, Kagawa, Japan between 2000 and 2020. Forty-three patients (18%) were excluded owing to a lack of data on PE, and thus we ultimately analyzed 200 patients. We reviewed the findings of computed tomography (CT) scans, including chest CT, and echocardiography after allo-HSCT. Only cases in which a radiologist or echocardiography technician detected PE were assessed. PE was stratified into localized PE and whole-circumference PE. The median age at transplantation was 52 years (range, 16 to 74 years). The study cohort comprised 106 patients (53%) age more than 50 years, 88 females (44%), and 112 males (56%). Primary diseases were myeloid neoplasms in 122 patients (61%) and lymphoid neoplasms in 78 (39%). The conditioning regimen was myeloablative in 142 patients (71%) and nonmyeloablative in 58 (29%). The median duration of follow-up was 47 months (range, 1 to 209 months). Forty patients developed PE within 100 days; localized in 23 (12%) and whole circumference in 17 (9%). In a multivariate analysis, significant risk factors for the development of PE within 100 days were late neutrophil engraftment (hazard ratio [HR], 5.24; 95% CI, 1.92 to 14.30; P < .01) and thrombotic microangiopathy (TMA) (HR, 8.23; 95% CI, 1.42 to 47.60; P = .02). The incidence of whole- circumference PE correlated with a lower overall survival (OS) rate (HR, 3.10; 95% CI, 1.34 to 7.17; P < .01) and higher nonrelapse mortality (NRM) rate (HR, 2.94; 95% CI, 1.18 to 7.32; P = .02). In the subgroup analysis, significant risk factors for the development of PE within 365 days were late neutrophil engraftment (HR, 3.13; 95% CI, 1.08 to 9.02; P = .04), the occurrence of chronic graft-versus-host disease (GVHD) (HR, 3.57; 95% CI, 1.19 to 10.70; P = .02), and disease recurrence (HR, 4.98; 95% CI, 1.43 to 17.30; P = .01). The development of whole-circumference PE also correlated with a lower OS rate (HR, 3.83; 95% CI, 1.65 to 8.89; P < .01) and a higher NRM rate (HR, 83.21; 95% CI, 17.75 to 390.10; P < .01). The overall occurrence of acute (grade II to IV) GVHD, chronic GVHD, and TMA were 36% (72 of 200), 39% (78 of 200), and 10% (19 of 200), respectively. In the entire cohort, the 3-year OS rate was 55%, and 3-year relapse and NRM rates were 37 and 14%, respectively. The present results demonstrate that risk factors for PE varied according to the time after allo-HSCT, and that whole-circumference PE at any time correlated with lower OS and higher NRM rates. A large-scale prospective study is needed to verify risk factors for PE and clarify whether immunosuppressive interventions based on the onset of PE improve the clinical prognosis of patients.

Background of patients with Aerococcus spp. detected in blood cultures, and drug sensitivity of Aerococcus spp.

This study aimed to review the clinical characteristics of patients with Aerococcus spp. detected by blood culture, and drug susceptibility of Aerococcus spp. All cases of Aerococcus spp. determined using blood culture between June 2013 and May 2020 in a single institution were included; patient information (age, sex, comorbidities, outcome, diagnosis, antimicrobial agents) was analyzed. The cohort comprised 25 patients (18 [72%] men and 7 [28%] women; median age, 84.5 [range, 75-87] years). Thirteen (52%) patients had urinary tract infections(UTI) caused by Aerococcus spp. All patients had a favorable prognosis, except 1 who died owing to infective endocarditis. Drug susceptibility testing showed that most isolates were susceptible to ß-lactams except 1. However, 24 (96%) cases were resistant to trimethoprim-sulfamethoxazole and 10 (40%) to quinolones. Aerococcus spp. are important causative agents of bacteremia and UTI. The increasing reports of Aerococcus spp. infections could lead to better treatment schemes and facilitate diagnosis.

Extent of disease affects the usefulness of fecal biomarkers in ulcerative colitis.

BACKGROUND: Fecal biomarkers are considered to be useful surrogate markers for endoscopic activity. Given the mechanisms of fecal biomarkers, we hypothesized that the extent of ulcerative colitis (UC; pancolitis, left-sided colitis, and proctitis) could affect the usefulness of fecal biomarkers for assessing endoscopic and clinical disease activity; however, few studies have evaluated the utility of fecal biomarkers in the disease extent of UC. METHODS: Fecal calprotectin, a fecal immunochemical test for hemoglobin, and fecal lactoferrin were used as fecal biomarkers. UC patients, who underwent colonoscopy within 30 days of the fecal biomarker test, participated in this observational study. Clinical and endoscopic disease activity was assessed using the Lichtiger Index and Mayo endoscopic subscore (MES), respectively. RESULTS: A total of 162 colonoscopies were performed on 133 UC patients. A correlation analysis between each biomarker and the MES for each disease-extent subgroup showed a decreased correlation in the proctitis compared with the other groups. With the exception of proctitis, it was possible to distinguish between MES 0 and MES ≥ 1 with high area-under-the-curve values for fecal calprotectin and fecal lactoferrin. The fecal immunochemical test for hemoglobin was superior at discriminating MES 0 for proctitis. CONCLUSIONS: For the practical application of fecal biomarkers for UC patients, it is necessary to consider disease extent before use. In particular, patients with proctitis exhibit a low correlation between stool biomarkers and endoscopic findings. The usefulness of these biomarkers for endoscopic remission is reduced, except for the fecal immunochemical test for hemoglobin.

Next-Generation Sequencing for Non-Ampullary Duodenal Carcinoma Suggesting the Existence of an Adenoma-Carcinoma Sequence.

Duodenal tumors with a sporadic adenoma-carcinoma sequence are extremely rare. For such clinically suspected cases without a specific family history, performing a comprehensive gene search is important to understand the germline mutation background. We present a 68-year-old woman without a genetic or familial history of familial adenomatous polyposis (FAP), Peutz-Jeghers syndrome, or Lynch syndrome who presented to Kosei Hospital, Japan, with exertional dyspnea induced by abdominal pain lasting 3 weeks. A duodenal tumor was suspected by contrast-enhanced computed tomography. Esophagogastroduodenoscopy showed a lesion accompanied by a white microprotuberance on the descending part of the duodenum opposite the papilla, with a giant ulcerative lesion at the center of the white lesion. Biopsy revealed a low-grade adenoma, high-grade adenoma, and adenocarcinoma. Immunohistochemical analysis of the adenoma and adenocarcinoma showed Ki-67, p53, cytokeratin 20, caudal-type homeobox 2, and carcinoembryonic antigen positivity and cytokeratin 7 negativity. The findings suggested the presence of an adenoma-adenocarcinoma sequence in duodenal carcinoma. However, in the mutational analysis using next-generation sequencing, c.4348C>T (p.Arg1450Ter) mutation in APC was detected in all normal mucosal, adenoma, and carcinoma tissues. This mutation is common in FAP patients. Even if the presence of an adenoma-adenocarcinoma sequence in duodenal carcinoma is suggested in cases without a familial FAP history, as in this case, genetic analysis may reveal FAP. Thus, performing a comprehensive genetic analysis of duodenal carcinoma patients with a possible adenoma-carcinoma sequence is necessary to explore their genetic background.

A case of infective endocarditis caused by "Neisseria skkuensis".

"Neisseria skkuensis" is a gram-negative coccus that is endemic in the human oral cavity, with only few reports of infection in humans. Herein, we report a case of a male patient in his sixties presenting with infective endocarditis (IE) caused by "N. skkuensis". To our knowledge, this is the second case of IE confirmed using 16S rRNA gene to have been caused by "N. skkuensis". The accurate diagnosis of rare or difficult-to-identify pathogens is a major challenge for clinical microbiological laboratories. Although Neisseria spp. are common in the oral cavity and are often seen in routine tests, identification of their biochemical properties and mass spectrometric analysis are difficult. In this case report, we describe the accurate identification of "N. skkuensis" by 16S rRNA gene sequencing analysis compared to other identification methods. Further cases of "N. skkuensis" are needed to fully evaluate the clinical approach of this detection method.

STK11 p.F354L Germline Mutation in a Case of Multiple Gastrointestinal Tumors.

Serine/threonine kinase 11 (STK11) is known as a critical tumor-suppressor gene that is frequently mutated in a broad spectrum of human cancers. Among these, the p.F354L mutation of STK11 has been identified in sporadic colon or lung cancer cases. Here, we report the case of a 75-year-old male patient who underwent surgical treatment for multiple tumors of the gastrointestinal system. Genetic mutations were screened in all resected samples, including duodenal high-grade adenoma, gastric high-grade adenoma, rectal adenocarcinoma, and liver metastasis of rectal adenocarcinoma, by next-generation sequencing for mutational hotspots involving 50 oncogenes and tumor suppressor genes. The characteristic hamartomatous polyp of Peutz-Jeghers syndrome was not detected in any tumor specimen. However, all samples as well as the normal rectal mucosa harbored the genetic mutation p.F354L in STK11. In addition, somatic mutations coexisted in the tumor samples, including KRAS p.A146T, TP53 p.G238X, and APC p.T1556fs in the duodenal adenoma; TP53 p.G238Y and APC p.T1556fs in the gastric adenoma; and TP53 p.R282W in the rectal adenocarcinoma and metastatic liver cancer. No somatic mutation was detected in the normal rectal mucosa as a control sample. To our knowledge, this is the first report of an STK11 germline mutation in a patient with multiple tumors of the gastrointestinal tract.

Discrimination of well-differentiated liposarcoma from benign lipoma on sonography: an uncontrolled retrospective study.

PURPOSE: Well-differentiated liposarcoma, the most common subtype of liposarcoma, should be discriminated from benign lipoma. However, features on sonography for discriminating these two types of tumor have not been fully investigated. The present study was therefore aimed at clarifying differences in sonographic findings between well-differentiated liposarcoma and lipoma. METHODS: The study population comprised 23 cases of well-differentiated liposarcoma and 181 cases of lipoma. We investigated differences in sonographic appearance and pathological findings between the two types of tumor. RESULTS: Well-differentiated liposarcoma tended to develop more frequently in older patients and in the lower extremities including the gluteal region, compared with lipoma. Concerning sonographic findings, both tumors exhibited well-defined margins and heterogeneous internal echogenicity, including typical tiny striated hyperechoic lines. Well-differentiated liposarcoma was characterized by a higher frequency of the following findings compared with lipoma: (1) deep location, (2) irregular shape, (3) large diameter, (4) hyperechogenicity compared to surrounding tissue, and (5) presence of vascularity on Doppler sonography (p < 0.01 each). Notably, hyperechogenicity corresponded to the intermingled sclerosing component within the adipocytic component when sonographic findings were compared with those of pathology. CONCLUSION: The present study suggests that several sonographic findings including hyperechogenicity and presence of vascularity might be key features for discriminating well-differentiated liposarcoma from lipoma.