Imaging of Facial Nerve With 3D-DESS-WE-MRI Before Parotidectomy: Impact on Surgical Outcomes

Objective@#The intra-parotid facial nerve (FN) can be visualized using three-dimensional double-echo steady-state waterexcitation sequence magnetic resonance imaging (3D-DESS-WE-MRI). However, the clinical impact of FN imaging using 3D-DESS-WE-MRI before parotidectomy has not yet been explored. We compared the clinical outcomes of parotidectomy in patients with and without preoperative 3D-DESS-WE-MRI. @*Materials and Methods@#This prospective, non-randomized, single-institution study included 296 adult patients who underwent parotidectomy for parotid tumors, excluding superficial and mobile tumors. Preoperative evaluation with 3D-DESS-WE-MRI was performed in 122 patients, and not performed in 174 patients. FN visibility and tumor location relative to FN on 3D-DESSWE-MRI were evaluated in 120 patients. Rates of FN palsy (FNP) and operation times were compared between patients with and without 3D-DESS-WE-MRI; propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) were used to adjust for surgical and tumor factors. @*Results@#The main trunk, temporofacial branch, and cervicofacial branch of the intra-parotid FN were identified using 3D-DESSWE-MRI in approximately 97.5% (117/120), 44.2% (53/120), and 25.0% (30/120) of cases, respectively. The tumor location relative to FN, as assessed on magnetic resonance imaging, concurred with surgical findings in 90.8% (109/120) of cases. Rates of temporary and permanent FNP did not vary between patients with and without 3D-DESS-WE-MRI according to PSM (odds ratio, 2.29 [95% confidence interval {CI} 0.64–8.25] and 2.02 [95% CI: 0.32–12.90], respectively) and IPTW (odds ratio, 1.76 [95% CI: 0.19–16.75] and 1.94 [95% CI: 0.20–18.49], respectively). Conversely, operation time for surgical identification of FN was significantly shorter with 3D-DESS-WE-MRI (median, 25 vs. 35 min for PSM and 25 vs. 30 min for IPTW, P < 0.001). @*Conclusion@#Preoperative FN imaging with 3D-DESS-WE-MRI facilitated anatomical identification of FN and its relationship to the tumor during parotidectomy. This modality reduced operation time for FN identification, but did not significantly affect postoperative FNP rates.

A prospective randomized controlled study comparing patient-reported scar evaluation of single-port versus multiport laparoscopic appendectomy for acute appendicitis

Purpose@#This study aimed to compare the postoperative outcomes and patient-surveyed scar assessments of single-port laparoscopic appendectomy (SPLA) with the outcomes of multiport laparoscopic appendectomy (MPLA). @*Methods@#Between August 2014 and November 2017, the prospective randomized study comprised 98 patients diagnosed with acute appendicitis and indicated for surgery. Fifty-one patients had MPLA and 47 patients received SPLA. The primary endpoint was the total score of Patient Scar Assessment Questionnaire (PSAQ) administered to patients 6 weeks after surgery. @*Results@#SPLA involved a shorter median operative time than MPLA (47.5 minutes vs. 60.0 minutes, p = 0.02). There were no apparent differences in the time before diet tolerance, length of hospital stay, and postoperative complication. SPLA patients had shorter total incision length (2.0 cm vs. 2.5 cm, p < 0.01) and required fewer analgesics on the day of surgery than MPLA patients (p = 0.011). The PSAQ favored the SPLA approach, revealing significant differences in total score (48 vs. 55, p = 0.026), appearance (15 vs. 18, p = 0.002), and consciousness (8 vs. 10, p = 0.005), while satisfaction with appearance and symptoms scale did not (p = 0.162 and p = 0.690, respectively). @*Conclusion@#The postoperative scar evaluated by the patient was better with SPLA than with MPLA, and patient satisfaction with the scar was comparable between the two techniques.

Findings of Intravenous Gadolinium Inner Ear Magnetic Resonance Imaging in Patients With Acute Low-Tone Sensorineural Hearing Loss

Objectives@#Acute low-tone sensorineural hearing loss (ALHL) is thought to have a different etiology from that of idiopathic sudden sensorineural hearing loss. We hypothesized that endolymphatic hydrops (EH) in the inner ear organ contributes to ALHL, even in patients without vertigo. This study investigated the presence of EH in ALHL and compared the clinical characteristics of patients with or without EH. @*Methods@#We retrospectively reviewed 38 patients diagnosed with ALHL without vertigo from January 2017 to March 2022. EH was measured in all patients using inner ear magnetic resonance imaging (MRI). In addition, we selected patients who showed only mid- or high-frequency hearing loss and had available MRI data as a control group and compared the ALHL and control groups. @*Results@#After treatment, the pure-tone average at low frequencies significantly improved compared to the initial hearing (P<0.001). Hearing recovery was observed in 63.1% of patients; however, the recovery rate did not differ based on the treatment method. During the follow-up period, six patients (15.8%) progressed to Meniere’s disease, and 18 (47.4%) experienced recurrence. In the ALHL group, the cochlear hydrops ratio on the affected side (0.34±0.09) was significantly higher than on the contralateral side (0.29±0.12) (P=0.005), and most patients showed hydrops in the apex area of the cochlea. Compared with the control group (0.25±0.15), the ALHL group showed a significantly higher cochlear hydrops ratio (P=0.043). The correlation analysis showed a tendency for hearing thresholds at low frequencies to increase as the hydrops ratio increased, albeit without statistical significance. @*Conclusion@#The cochlear hydrops ratio, especially in the apex area on the affected side, was significantly higher in patients with ALHL, suggesting that EH in the cochlea contributes to the pathogenesis of ALHL.

Survival analysis of breast cancer patients after diagnosis of second primary malignancies, focusing on the second primary hematologic malignancy

Purpose@#Although the overall survival (OS) of breast cancer patients is increasing with improved detection and therapies, so is the risk of breast cancer patients developing subsequent malignancies. We investigated the OS of breast cancer survivors according to sites of second primary malignancies (SPM). The OS of the second primary hematologic malignancy (SPHM) was then compared with that of metastatic breast cancer (MBC). @*Methods@#We retrospectively analyzed patients diagnosed with primary breast cancer between 1998 and 2019. Only those with SPM were eligible for analysis. First, the OS of patients with SPM diagnosed as the first event after the diagnosis of breast cancer was analyzed. Next, the OS of patients with SPHM, with or without breast cancer relapse, was compared with that of patients with MBC, matched using the propensity score. @*Results@#Patients diagnosed with SPM without breast cancer relapse as the first event had a significantly better OS than did patients with MBC, but the OS of those with SPHM as the first event did not differ significantly from that of patients with MBC (hazard ratio [HR], 1.558; 95% confidence interval [CI], 0.856–2.839; P = 0.147). The OS of patients with SPHM with or without breast cancer relapse was worse than that of the MBC group after propensity score matching (HR, 1.954; 95% CI, 1.045–3.654; P = 0.036). @*Conclusion@#Prognosis of SPM diagnosed as the first event was statistically better than that of MBC, except in case of SPHM. Patients with SPHM, with or without MBC, showed poor OS before and after propensity score matching.

Metachronous carcinoma at the colostomy site after abdominoperineal resection of rectal cancer: a case report

Metachronous carcinoma at the colostomy site is very rare after abdominoperineal resection. A 53-year-old male patient underwent an abdominoperineal resection 6 years earlier for rectal cancer developed metachronous carcinoma at the site of stoma. A portion of the colon, including the stoma and the surrounding skin, was resected and a new stoma was created in the transverse colon. Although the occurrence of carcinoma at the stoma site is a rare condition, careful observation for the stoma and colonoscopy for surveillance are necessary.

Short- and long-term outcomes of laparoscopic segmental left colectomy for splenic flexure colon cancer: comparison with propensity score matching

Purpose@#Splenic flexure colon cancer (SFCC) is a rare disease that accounts for 2%–8% of colorectal cancers, and the extent of surgery and resection is still debatable. There have also been few studies on the safety and feasibility of laparoscopic surgery for SFCC. The purpose of this study is to evaluate outcomes and prognoses of surgery for SFCC. @*Methods@#We included patients with stage 1 to 3 who had undergone laparoscopic surgery for distal transverse-to-sigmoid colon cancer at 2 hospitals from March 2004 to December 2016 and collected data by retrospective design. We defined SFCC as being cancer between distal transverse and proximal descending colon. The short- and long-term outcomes of the anterior resection (AR) group (those patients who had undergone laparoscopic AR for mid and distal descending to sigmoid colon cancer) and the left colon resection (LR) group (those who had undergone laparoscopic segmental left colectomy for SFCC) were compared using propensity score matching. @*Results@#The median follow-up period was 60 months. The numbers of subjects in the AR and the LR groups were 948 and 118. After 2:1 propensity score matching, 236 vs. 118 patients were selected. There was no significant difference in 5-year disease-free survival (80.7% vs. 78.6%, P = 0.607), and both the 5-year overall survival (89.2% vs. 88.2%, P = 0.563) as well as short-term outcomes showed no statistical difference in most of the variables. @*Conclusion@#Laparoscopic segmental left colectomy can be one option among the standard procedures for SFCC.

Adjuvant chemotherapy for patients with stage II high-risk and III colon cancer: Hindering factors to adherence and impact on long-term survival

Purpose@#Adjuvant chemotherapy is recommended after curative surgery in patients with colon cancer of high-risk stage II and stage III. However, a considerable number of patients cannot complete the scheduled adjuvant treatment for various reasons. This study investigates the hindering factors to the adherence to adjuvant chemotherapy and their impact on long-term survival. @*Methods@#A retrospective study was conducted for patients with colon cancer and had curative resection from 2009 to 2014. Among patients with pathologic stage II and III, stage II with low-risk features, double primary cancers, R2 resection cases were excluded. Patients were grouped into three groups: no-adjuvant therapy, adjuvant therapy for less than 3 months, and more than 3 months. Factors for withdrawal and the oncologic outcome were analyzed. @*Results@#Of 571 patients, adjuvant chemotherapy was recommended in 403. One hundred and sixteen patients (28.8%) did not receive adjuvant chemotherapy, 78 (19.4%) withdrew within 3 months, and 209 (51.9%) maintained for more than 3 months. Factors for not receiving adjuvant chemotherapy or withdrawing within 3 months were older than 70 and American Society of Anesthesiologists class 3 or higher. Main reasons for discontinuation before 3 months were chemotoxicity and patient’s refusal. The long-term oncologic outcome of the patients who received adjuvant chemotherapy for more than 3 months was significantly better than others. @*Conclusion@#No-adjuvant therapy or receiving them for lesser than 3 months is significantly affected by the patient’s performance status and social support, which coincides with a poor oncologic outcome. Social support and rehabilitation system may help to improve the survival outcome.

Enterovesical Fistula From Meckel Diverticulum

Meckel diverticulum is a common congenital malformation of the gastrointestinal tract and can cause complications such as ulceration, hemorrhage, intussusception, and perforation. This report describes a very rare complication of an enterovesical fistula associated with chronic Meckel diverticulum. A 51-year-old male presented with over 10 years of persistent pyuria. Tests were performed to rule out malignancy, including serum prostate-specific antigen level, urine cytology, bacterial culture, cystoscopy, and bladder computed tomography. An enterovesical fistula was identified, and laparoscopic exploration was performed. The findings suggested enterovesical fistula formation caused by chronic inflammation at the tip of a Meckel diverticulum. Segmental resection of the small bowel including the diverticulum and primary repair of the urinary bladder along with partial cystectomy were performed. The postoperative clinical course was uneventful. An enterovesical fistula is a very rare complication resulting from chronic inflammation of a Meckel diverticulum.

Adjuvant chemotherapy for patients with stage II high-risk and III colon cancer: Hindering factors to adherence and impact on long-term survival

Purpose@#Adjuvant chemotherapy is recommended after curative surgery in patients with colon cancer of high-risk stage II and stage III. However, a considerable number of patients cannot complete the scheduled adjuvant treatment for various reasons. This study investigates the hindering factors to the adherence to adjuvant chemotherapy and their impact on long-term survival. @*Methods@#A retrospective study was conducted for patients with colon cancer and had curative resection from 2009 to 2014. Among patients with pathologic stage II and III, stage II with low-risk features, double primary cancers, R2 resection cases were excluded. Patients were grouped into three groups: no-adjuvant therapy, adjuvant therapy for less than 3 months, and more than 3 months. Factors for withdrawal and the oncologic outcome were analyzed. @*Results@#Of 571 patients, adjuvant chemotherapy was recommended in 403. One hundred and sixteen patients (28.8%) did not receive adjuvant chemotherapy, 78 (19.4%) withdrew within 3 months, and 209 (51.9%) maintained for more than 3 months. Factors for not receiving adjuvant chemotherapy or withdrawing within 3 months were older than 70 and American Society of Anesthesiologists class 3 or higher. Main reasons for discontinuation before 3 months were chemotoxicity and patient’s refusal. The long-term oncologic outcome of the patients who received adjuvant chemotherapy for more than 3 months was significantly better than others. @*Conclusion@#No-adjuvant therapy or receiving them for lesser than 3 months is significantly affected by the patient’s performance status and social support, which coincides with a poor oncologic outcome. Social support and rehabilitation system may help to improve the survival outcome.

Adenocarcinoma of the minor salivary gland with concurrent MAML2 and EWSR1 alterations

Salivary gland tumors are histologically diverse, and each entity has distinctive histopathological and molecular features. We report two cases of salivary gland tumors with unique histological and molecular findings, which have not been documented previously. The tumors were located in the base of the tongue in both patients. Most tumor cells were arranged in cords and nests, giving a trabecularlike appearance. Focally, glandular structures with intraluminal mucin and perivascular pseudorosette-like configurations were identified. Tumor cells had eosinophilic to clear cytoplasm, and showed mild nuclear atypia. They were positive for pancytokeratin and negative for S-100, p63, c-KIT, androgen receptor, and neuroendocrine markers. Multiple foci of capsular or lymphovascular invasion were identified, but the Ki-67 labeling index was low (< 5%). Fluorescence in situ hybridization revealed concurrent alterations of MAML2 and EWSR1 gene. Further investigations with a larger number of cases with similar histological and molecular features will accurately classify this tumor.

Single incision laparoscopic totally extraperitoneal hernioplasty: lessons learned from 1,231 procedures

Purpose@#Although there are many articles about single incision laparoscopic (SIL) hernioplasty, a large-scale study or article about its long-term outcome has not been reported yet. The aim of this study is to assess short- and long-term outcomes of SIL totally extraperitoneal (TEP) hernia repair with large number of cases. @*Methods@#A prospectively collected database containing details of 1,231 procedures in 1,129 consecutive patients who underwent SIL-TEP hernia repair between June 2010 and December 2017 at a single institution was retrospectively analyzed. SIL-TEP hernia repair was performed using a glove single port device and standard laparoscopic instruments.Recurrence rate of SIL-TEP hernia repair was analyzed by a telephone questionnaire. @*Results@#Among 1,129 patients, 1,027 (91.0%) had unilateral hernia and 102 (9.0%) had bilateral hernia. There were 12 (1.1%) conversions to single or 3 ports laparoscopic transabdominal preperitoneal hernioplasty or Lichtenstein repair. Mean operative time was 40.3 minutes for unilateral hernia and 61.6 minutes for bilateral hernia. Intraoperative complication rate was 21.8%. Most intraoperative complications were peritoneum or sac tearing (20.1%). Postoperative complications occurred in 97 (8.6%) cases, most of which were minor morbidity except for 1 mesh infection. Five-year recurrence rate was 4%. @*Conclusion@#SIL-TEP hernia repair is safe and technically feasible with acceptable short- and long-term outcomes. Largescale randomized controlled trials comparing SIL-TEP hernia repair with conventional laparoscopic TEP are needed to confirm these results.

Enterovesical Fistula From Meckel Diverticulum

Meckel diverticulum is a common congenital malformation of the gastrointestinal tract and can cause complications such as ulceration, hemorrhage, intussusception, and perforation. This report describes a very rare complication of an enterovesical fistula associated with chronic Meckel diverticulum. A 51-year-old male presented with over 10 years of persistent pyuria. Tests were performed to rule out malignancy, including serum prostate-specific antigen level, urine cytology, bacterial culture, cystoscopy, and bladder computed tomography. An enterovesical fistula was identified, and laparoscopic exploration was performed. The findings suggested enterovesical fistula formation caused by chronic inflammation at the tip of a Meckel diverticulum. Segmental resection of the small bowel including the diverticulum and primary repair of the urinary bladder along with partial cystectomy were performed. The postoperative clinical course was uneventful. An enterovesical fistula is a very rare complication resulting from chronic inflammation of a Meckel diverticulum.

The Emerging Role of Eosinophils as Multifunctional Leukocytes in Health and Disease

Eosinophils are terminally differentiated cytotoxic effector cells that have a role in parasitic infections and allergy by releasing their granule-derived cytotoxic proteins. However, an increasing number of recent observations indicate that eosinophils are not only associated with the pathogenesis of a wide range of diseases, but also contribute to the maintenance of homeostatic responses in previously underappreciated diverse tissues, such as the gastrointestinal (GI) tract and adipose tissue. In this review, we describe biological characteristics of eosinophils, as their developmental properties, permissive proliferation and survival, degranulation activity, and migration properties enable them to distribute to both homeostatic and inflamed tissues. We describe pathologic aspects of eosinophils with a role in asthma and in various GI diseases, including eosinophilic GI disorders, inflammatory bowel disease, and radiation-induced enteropathy. Finally, we discuss the beneficial role of eosinophils, which contribute to the resolution of pathogenic conditions and to the modulation of homeostatic biologic responses.

Normal Anatomy of Cranial Nerves III–XII on Magnetic Resonance Imaging

Because of the inherent complex anatomy and functional arrangement of the cranial nerves (CNs), neuroimaging of cranial neuropathy is challenging. With recent advances in magnetic resonance imaging (MRI) techniques, the cause of cranial neuropathy can now be detected in many cases. As an active multidisciplinary team member of cranial neuropathy, it is essential for the neuroradiologist to be familiar with the detailed anatomy of the CNs on MRI. This review contains the basic MRI anatomy of CNs III–XII according to a segmental classification from the brain stem to the extracranial region. The optimal imaging options to best evaluate the specific segment of the CNs will also be discussed briefly.

Surgical Management of Sigmoid Volvulus: A Multicenter Observational Study

Purpose@#This study aimed to evaluate real-world clinical outcomes from surgically treated patients for sigmoid volvulus. @*Methods@#Five tertiary centers participated in this retrospective study with data collected from October 2003 through September 2018, including demographic information, preoperative clinical data, and information on laparoscopic/open and elective/emergency procedures. Outcome measurements included operation time, postoperative hospitalization, and postoperative morbidity. @*Results@#Among 74 patients, sigmoidectomy was the most common procedure (n = 46), followed by Hartmann’s procedure (n = 23), and subtotal colectomy (n = 5). Emergency surgery was performed in 35 cases (47.3%). Of the 35 emergency patients, 34 cases (97.1%) underwent open surgery, and a stoma was established for 26 patients (74.3%). Elective surgery was performed in 39 cases (52.7%), including 21 open procedures (53.8%), and 18 laparoscopic surgeries (46.2%). Median laparoscopic operation time was 180 minutes, while median open surgery time was 130 minutes (P < 0.001). Median postoperative hospitalization was 11 days for laparoscopy and 12 days for open surgery. There were 20 postoperative complications (27.0%), and all were resolved with conservative management. Emergency surgery cases had a higher complication rate than elective surgery cases (40.0% vs. 15.4%, P = 0.034). @*Conclusion@#Relative to elective surgery, emergency surgery had a higher rate of postoperative complications, open surgery, and stoma formation. As such, elective laparoscopic surgery after successful sigmoidoscopic decompression may be the optimal clinical option.

Retrospective study on prevalence of recurrent inguinal hernia: a large-scale multi-institutional study

PURPOSE: We conducted a multi-institutional analysis to establish the epidemiological characteristics of recurrent inguinal hernia following hernia repair in patients across 4 institutions in Korea.METHODS: The retrospectively reviewed data included patient characteristics, hernia location, year of primary operation, type of hernia, timing of recurrence, primary operation type, and whether a mesh was used.RESULTS: Among 4,604 patients who underwent hernia repair surgery, 255 patients (5.5%; 13 females and 242 males; mean age, 63 years) were found to have recurrent hernia from January 2010 to April 2017. Recurrent indirect inguinal and direct hernias were observed in 47.1% and 49.4% of the patients, respectively. The recurrence of hernias within 1 year of surgery was the highest at 17.25%. Early and late recurrences was observed in 23.5% and 66.5% of the patients, respectively. Among the patients, 81.6% underwent open hernia repair at the time of initial surgery.CONCLUSION: Recurrence of hernia is most common in the first year after the initial surgery, and 23.5% of recurrent inguinal hernia was developed within 2 years. Patients underwent surgery after an average of 116 months (median value, 64 months) following the first operation. In patients with recurrent hernia, direct hernia was seen more frequent than indirect hernia whereas indirect hernia occurred more in patients with primary hernia.

Surgical Management of Sigmoid Volvulus: A Multicenter Observational Study

Purpose@#This study aimed to evaluate real-world clinical outcomes from surgically treated patients for sigmoid volvulus. @*Methods@#Five tertiary centers participated in this retrospective study with data collected from October 2003 through September 2018, including demographic information, preoperative clinical data, and information on laparoscopic/open and elective/emergency procedures. Outcome measurements included operation time, postoperative hospitalization, and postoperative morbidity. @*Results@#Among 74 patients, sigmoidectomy was the most common procedure (n = 46), followed by Hartmann’s procedure (n = 23), and subtotal colectomy (n = 5). Emergency surgery was performed in 35 cases (47.3%). Of the 35 emergency patients, 34 cases (97.1%) underwent open surgery, and a stoma was established for 26 patients (74.3%). Elective surgery was performed in 39 cases (52.7%), including 21 open procedures (53.8%), and 18 laparoscopic surgeries (46.2%). Median laparoscopic operation time was 180 minutes, while median open surgery time was 130 minutes (P < 0.001). Median postoperative hospitalization was 11 days for laparoscopy and 12 days for open surgery. There were 20 postoperative complications (27.0%), and all were resolved with conservative management. Emergency surgery cases had a higher complication rate than elective surgery cases (40.0% vs. 15.4%, P = 0.034). @*Conclusion@#Relative to elective surgery, emergency surgery had a higher rate of postoperative complications, open surgery, and stoma formation. As such, elective laparoscopic surgery after successful sigmoidoscopic decompression may be the optimal clinical option.

Inguinal hernia surgery in Korea: nationwide data from 2007–2015

PURPOSE: The aim of this study is to analyze inguinal hernia in Korea based on the nationwide data. METHODS: Retrospective analysis of nationwide data obtained from the Health Insurance Review & Assessment Service database for surgical repair of inguinal hernia from January, 2007 to December, 2015 was performed. RESULTS: A total of 314,238 cases of inguinal hernia surgery were performed during 9 years. The mean number of inguinal hernia surgery per year was 34,604 (range, 30,065–36,928). The proportion of male patient was 87%. Patients between the age of 1 to 5 years (17.3%) and of 60 to 69 years (17.4%) constituted the 2 dominant groups for inguinal hernia repair. A slight increase in repair for recurrent inguinal hernia, 1.9% to 3.2%, was observed from 2007 to 2015. The rate of concurrent bowel resection decreased from 1.9% to 0.6%. The total cost of inguinal hernia surgery was increased up to 1.68 times from 2007 to 2015 ($856 to $1,439), although the number of hospital days was decreased from 4.7 to 3.7 days. The rate of laparoscopic surgery was increased to 29.5% in 2015. CONCLUSION: A mean number of 34,604 cases of inguinal hernia surgery have been carried out annually in Korea. The age distribution for inguinal hernia repair demonstrates bimodal peak at early childhood and old age. The proportion of laparoscopic surgery of inguinal hernia has been increasing for the past 9 years. The length of hospital stay and the rate of combined bowel resection have decreased.

Organ Preservation Strategies After Neoadjuvant Chemoradiotherapy for Locally Advanced Rectal Cancer

Standard use of neoadjuvant chemoradiotherapy, total mesorectal excision, and postoperative adjuvant chemotherapy in locally advanced rectal cancer has tremendously improved oncologic outcomes over the past several decades. However, these improvements come with costs of significant morbidity and poor quality of life. Along with developments in imaging techniques, clinical experience and evidence have identified a certain subgroup of patients that have exceptionally good clinical outcomes while preserving quality of life. Driven by patient demand and interest in preserving quality of life, numerous organ preservation treatment strategies for managing rectal cancer are rapidly evolving. Herein, the flow of research in organ preservation strategies and counter arguments are discussed.

Distinguishing between Thymic Epithelial Tumors and Benign Cysts via Computed Tomography

OBJECTIVE: To investigate whether computed tomography (CT) and fluorine-18-labeled fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) may be applied to distinguish thymic epithelial tumors (TETs) from benign cysts in the anterior mediastinum. MATERIALS AND METHODS: We included 262 consecutive patients with pathologically proven TETs and benign cysts 5 cm or smaller who underwent preoperative CT scans. In addition to conventional morphological and ancillary CT findings, the relationship between the lesion and the adjacent mediastinal pleura was evaluated qualitatively and quantitatively. Mean lesion attenuation was measured on CT images. The maximum standardized uptake value (SUVmax) was obtained with FDG-PET scans in 40 patients. CT predictors for TETs were identified with multivariate logistic regression analysis. For validation, we assessed the diagnostic accuracy and inter-observer agreement between four radiologists in a size-matched set of 24 cysts and 24 TETs using a receiver operating characteristic curve before and after being informed of the study findings. RESULTS: The multivariate analysis showed that post-contrast attenuation of 60 Hounsfield unit or higher (odds ratio [OR], 12.734; 95% confidence interval [CI], 2.506–64.705; p = 0.002) and the presence of protrusion from the mediastinal pleura (OR, 9.855; 95% CI, 1.749–55.535; p = 0.009) were the strongest CT predictors for TETs. SUVmax was significantly higher in TETs than in cysts (5.3 ± 2.4 vs. 1.1 ± 0.3; p < 0.001). After being informed of the study findings, the readers' area under the curve improved from 0.872–0.955 to 0.949–0.999 (p = 0.066–0.149). Inter-observer kappa values for protrusion were 0.630–0.941. CONCLUSION: Post-contrast CT attenuation, protrusion from the mediastinal pleura, and SUVmax were useful imaging features for distinguishing TETs from cysts in the anterior mediastinum.