PurposePrimary epiploic appendagitis (PEA) is a rare cause of an acute abdomen. It can be clinically misdiagnosed as either diverticulitis or appendicitis on clinical examination because the clinical symptoms and signs of PEA are non-specific. The present study was performed to describe the clinical characteristics of PEA and to assess the differences between PEA and diverticulitis.MethodsWe reviewed the clinical records and radiologic findings of 31 consecutive patients with PEA and compared them with those of patients with diverticulitis without complications.ResultsIn most cases, abdominal pain was localized to the right (13 cases, 41.9%) or left (13 cases, 41.9%) lower quadrants. Gastrointestinal symptoms such as nausea and vomiting were infrequent, and localized tenderness without peritoneal irritation was common. All patients were afebrile, and only 4 patients (12.9%) showed leukocytosis. In all cases except one, a pericolic fatty mass with a hyperattenuated ring was observed on computed tomography. Patients with left PEA were younger than those with diverticulitis (41.4 ± 11.9 vs. 69.7 ± 13.3, P < 0.001), and the mean body mass index was higher in patients with left PEA (26.4 ± 2.9 vs. 22.6 ± 3.4, P = 0.01). Whereas one patient (6.7%) with left PEA showed leukocytosis, the incidence of leukocytosis in patients with diverticulitis was 80% (8/10) (P < 0.001).ConclusionIn patients with an acute abdomen showing localized tenderness without associated symptoms or leukocytosis, a high index of suspicion for PEA is necessary. For correct diagnosis and proper management, it would useful for surgeons to be aware of the computed tomographic findings and the natural course of the disease.

MicroRNA (miRNA) has a critical effect on tumorigenesis through post-transcriptional modification and is considered to be potential biomarkers for cancer diagnosis and treatment monitoring. We evaluated the expression pattern of three selected miRNAs (miR-21, miR-155, and let-7a) to evaluate their potential roles by quantitative reverse transcription-polymerase chain reaction using formalinfixed and paraffin-embedded tissues of 63 surgically resected pulmonary neuroendocrine (NE) tumors (19 typical carcinoids (TCs), 6 atypical carcinoids (ACs), 19 large cell NE carcinomas (LCNECs), and 19 small cell lung carcinomas (SCLCs). Control amplification for U6 small nuclear RNA (U6) was performed in all samples. Normalized Ct values were calculated (CtExperimental miRNA-CtU6) for each case and recorded. The expression levels of miR-21 and miR-155 were significantly higher in high-grade NE carcinomas (LCNECs and SCLCs) than in carcinoid tumors (TCs and ACs) (each P < 0.001). The expression level of miR-21 in carcinoid tumors with lymph node metastasis was significantly higher than in carcinoid tumors without lymph node metastasis (P = 0.010). To the best of our knowledge, the present study is the first to examine the expression patterns of miR-21 and miR-155 as an adjunctive diagnostic tool or clinically relevant biomarkers for pulmonary NE tumors.

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Molecular analysis is traditionally performed on tumor tissue. Although the number of mandatory tests for treatment decisions increases in patients with advanced non-small cell lung cancer (NSCLC), it is difficult to secure adequate tumor tissue for this purpose [1]. Small biopsy specimens, cell blocks, or aspirates are often the only available samples in patients with advanced NSCLC [2,3]. It is difficult to repeat tissue biopsies because they are invasive. Liquid biopsy could be an alternative or a complementary minimally invasive method for detecting molecular changes in NSCLC [1,2,4,5]. The clinical use of liquid biopsy to select patients with advanced NSCLC who are candidates for third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) therapy has been demonstrated in many clinical trials [6-10]. The United States Food and Drug Administration (FDA) approved Cobas EGFR Mutation Test v2 (Roche, Indianapolis, IN, USA) in 2018 as a companion diagnostic for third-generation EGFR TKI based on these results [11]. The Korea National Health Insurance Service (NHIS) has covered circulating cell-free tumor DNA (ctDNA) tests for EGFR mutations in advanced NSCLC since 2018. In this review, we present the current status and future perspectives of liquid biopsy in patients with NSCLC. BIOLOGY OF CIRCULATING TUMOR DNA Liquid biopsy refers to the collection and analysis of analytes from various body fluids such as blood, urine, sputum, and pleural fluid [12-14]. Different analytes can be present in a liquid biopsy including circulating tumor cells (CTCs), circulating cell-free DNAs (cfDNAs), circulating tumor RNAs (ctRNAs), circulating exosomes, tumor-educated platelets, proteins, and metabolites [15,16]. CTCs are intact, viable tumor cells circulating in the blood [12]. Cancer releases single or clusters of CTCs into the bloodstream during the course of hematogenous spread. cfDNA refers to all circulating DNA in body fluids. cfDNA can be derived from neoplastic as well as non-neoplastic cells [15,16]. cfDNA can be detected in other body fluids, including urine, saliva, or cerebrospinal fluid. ctDNA refers to a subgroup

Mutations of the epidermal growth factor receptor (EGFR) are the strongest predictive factor for response to EGFR tyrosine kinase inhibitors (TKIs), such as gefitinib and erlotinib. EGFR TKIs are approved in Korea as a first-line treatment for lung cancer patients with mutated EGFR. Rapid and accurate EGFR mutation testing is essential for patient selection and establishing targeted therapies with EGFR TKIs. Thus, a standard set of guideline recommendations for EGFR mutation testing suitable for the Korean medical community is necessary. In this article, we propose a set of guideline recommendations for EGFR mutation testing that was discussed and approved by the Cardiopulmonary Pathology Study Group of the Korean Society of Pathologists.