Purpose: Claudin 18.2 (CLDN18.2) has emerged as a promising therapeutic target for CLDN18.2-expressing gastric cancer (GC). We sought to examine the heterogeneity of CLDN18.2 expression between primary GC (PGC) and metastatic GC (MGC) using various scoring methods. Materials and Methods: We retrospectively analyzed data from 102 patients with pathologically confirmed paired primary and metastatic gastric or gastroesophageal junction adenocarcinomas. CLDN18.2 expression was evaluated through immunohistochemistry on formalin-fixed paraffin-embedded tissue samples. We assessed CLDN18.2 positivity using multiple scoring approaches, including the immunoreactivity score, H-score, and the percentage of tumor cells showing moderate-to-strong staining intensity. We analyzed the concordance rates between PGC and MGC and the association of CLDN18.2 positivity with clinicopathological features. Results: CLDN18.2 positivity varied from 25% to 65% depending on the scoring method, with PGC consistently showing higher expression levels than MGC. Intratumoral heterogeneity was noted in 25.5% of PGCs and 19.6% of MGCs. Intertumoral heterogeneity, manifesting as discordance in CLDN18.2 positivity between PGC and MGC, was observed in about 20% of cases, with moderate agreement across scoring methods (κ=0.47 to 0.60).In PGC, higher CLDN18.2 positivity correlated with synchronous metastasis, presence of peritoneal metastasis, poorly differentiated grade, and biopsy specimens. In MGC, positivity was associated with synchronous metastasis, presence of peritoneal metastasis, and metastatic peritoneal tissues. Conclusions CLDN18.2 expression demonstrates significant heterogeneity between PGC and MGC, with a 20% discordance rate. Comprehensive tissue sampling and reassessment of CLDN18.2 status are crucial, especially before initiating CLDN18.2-targeted therapies.

Purpose: Claudin 18.2 (CLDN18.2) has emerged as a promising therapeutic target for CLDN18.2-expressing gastric cancer (GC). We sought to examine the heterogeneity of CLDN18.2 expression between primary GC (PGC) and metastatic GC (MGC) using various scoring methods. Materials and Methods: We retrospectively analyzed data from 102 patients with pathologically confirmed paired primary and metastatic gastric or gastroesophageal junction adenocarcinomas. CLDN18.2 expression was evaluated through immunohistochemistry on formalin-fixed paraffin-embedded tissue samples. We assessed CLDN18.2 positivity using multiple scoring approaches, including the immunoreactivity score, H-score, and the percentage of tumor cells showing moderate-to-strong staining intensity. We analyzed the concordance rates between PGC and MGC and the association of CLDN18.2 positivity with clinicopathological features. Results: CLDN18.2 positivity varied from 25% to 65% depending on the scoring method, with PGC consistently showing higher expression levels than MGC. Intratumoral heterogeneity was noted in 25.5% of PGCs and 19.6% of MGCs. Intertumoral heterogeneity, manifesting as discordance in CLDN18.2 positivity between PGC and MGC, was observed in about 20% of cases, with moderate agreement across scoring methods (κ=0.47 to 0.60).In PGC, higher CLDN18.2 positivity correlated with synchronous metastasis, presence of peritoneal metastasis, poorly differentiated grade, and biopsy specimens. In MGC, positivity was associated with synchronous metastasis, presence of peritoneal metastasis, and metastatic peritoneal tissues. Conclusions CLDN18.2 expression demonstrates significant heterogeneity between PGC and MGC, with a 20% discordance rate. Comprehensive tissue sampling and reassessment of CLDN18.2 status are crucial, especially before initiating CLDN18.2-targeted therapies.

Purpose: Claudin 18.2 (CLDN18.2) has emerged as a promising therapeutic target for CLDN18.2-expressing gastric cancer (GC). We sought to examine the heterogeneity of CLDN18.2 expression between primary GC (PGC) and metastatic GC (MGC) using various scoring methods. Materials and Methods: We retrospectively analyzed data from 102 patients with pathologically confirmed paired primary and metastatic gastric or gastroesophageal junction adenocarcinomas. CLDN18.2 expression was evaluated through immunohistochemistry on formalin-fixed paraffin-embedded tissue samples. We assessed CLDN18.2 positivity using multiple scoring approaches, including the immunoreactivity score, H-score, and the percentage of tumor cells showing moderate-to-strong staining intensity. We analyzed the concordance rates between PGC and MGC and the association of CLDN18.2 positivity with clinicopathological features. Results: CLDN18.2 positivity varied from 25% to 65% depending on the scoring method, with PGC consistently showing higher expression levels than MGC. Intratumoral heterogeneity was noted in 25.5% of PGCs and 19.6% of MGCs. Intertumoral heterogeneity, manifesting as discordance in CLDN18.2 positivity between PGC and MGC, was observed in about 20% of cases, with moderate agreement across scoring methods (κ=0.47 to 0.60).In PGC, higher CLDN18.2 positivity correlated with synchronous metastasis, presence of peritoneal metastasis, poorly differentiated grade, and biopsy specimens. In MGC, positivity was associated with synchronous metastasis, presence of peritoneal metastasis, and metastatic peritoneal tissues. Conclusions CLDN18.2 expression demonstrates significant heterogeneity between PGC and MGC, with a 20% discordance rate. Comprehensive tissue sampling and reassessment of CLDN18.2 status are crucial, especially before initiating CLDN18.2-targeted therapies.

Objective: Traumatic occult pneumothorax is defined as a pneumothorax that cannot be identified with a simple chest X-ray and can be detected only by chest computed tomography (CT). The purpose of this study was to retrospectively recognize the difference between thoracostomy and conservative treatment of traumatic occult pneumothorax. Methods: Among the thoracic trauma inpatients who visited a single emergency room (ER) from January 2021 to May 2022, adult patients aged over 18 years, diagnosed with traumatic pneumothorax who survived their ER stay and with abnormalities were included as the final study subjects and their histories were compared. Results: Of the total of 269 thoracic trauma patients, 110 were diagnosed with traumatic pneumothorax, of which 30 were traumatic occult pneumothorax patients. Multiple logistic regression analyses performed in the traumatic occult pneumothorax patient group showed that as the pneumothorax size increased, the probability of finding an occult pneumothorax decreased (odds ratio [OR]=0.93; 95% confidence interval [CI], 0.89-0.98). In very severe cases of rib fractures (OR=0.65; 95% CI, 0.43-0.98), the probability of detecting occult pneumothorax was reduced. Among the patients with traumatic occult pneumothorax, 15 patients underwent thoracostomy. Cases of hemothorax (70%; P=0.05), surgery (26.67%; P<0.01), and higher injury severity scores (12.87±7.69; P=0.02) were more common in the thoracostomy group. Conclusion Usually traumatic occult pneumothorax is treated conservatively with regular follow-up, but thoracostomy is necessary when it is accompanied by hemothorax and for patients requiring surgery and having a higher injury severity score.

Objective: Traumatic occult pneumothorax is defined as a pneumothorax that cannot be identified with a simple chest X-ray and can be detected only by chest computed tomography (CT). The purpose of this study was to retrospectively recognize the difference between thoracostomy and conservative treatment of traumatic occult pneumothorax. Methods: Among the thoracic trauma inpatients who visited a single emergency room (ER) from January 2021 to May 2022, adult patients aged over 18 years, diagnosed with traumatic pneumothorax who survived their ER stay and with abnormalities were included as the final study subjects and their histories were compared. Results: Of the total of 269 thoracic trauma patients, 110 were diagnosed with traumatic pneumothorax, of which 30 were traumatic occult pneumothorax patients. Multiple logistic regression analyses performed in the traumatic occult pneumothorax patient group showed that as the pneumothorax size increased, the probability of finding an occult pneumothorax decreased (odds ratio [OR]=0.93; 95% confidence interval [CI], 0.89-0.98). In very severe cases of rib fractures (OR=0.65; 95% CI, 0.43-0.98), the probability of detecting occult pneumothorax was reduced. Among the patients with traumatic occult pneumothorax, 15 patients underwent thoracostomy. Cases of hemothorax (70%; P=0.05), surgery (26.67%; P<0.01), and higher injury severity scores (12.87±7.69; P=0.02) were more common in the thoracostomy group. Conclusion Usually traumatic occult pneumothorax is treated conservatively with regular follow-up, but thoracostomy is necessary when it is accompanied by hemothorax and for patients requiring surgery and having a higher injury severity score.

Objective: Traumatic occult pneumothorax is defined as a pneumothorax that cannot be identified with a simple chest X-ray and can be detected only by chest computed tomography (CT). The purpose of this study was to retrospectively recognize the difference between thoracostomy and conservative treatment of traumatic occult pneumothorax. Methods: Among the thoracic trauma inpatients who visited a single emergency room (ER) from January 2021 to May 2022, adult patients aged over 18 years, diagnosed with traumatic pneumothorax who survived their ER stay and with abnormalities were included as the final study subjects and their histories were compared. Results: Of the total of 269 thoracic trauma patients, 110 were diagnosed with traumatic pneumothorax, of which 30 were traumatic occult pneumothorax patients. Multiple logistic regression analyses performed in the traumatic occult pneumothorax patient group showed that as the pneumothorax size increased, the probability of finding an occult pneumothorax decreased (odds ratio [OR]=0.93; 95% confidence interval [CI], 0.89-0.98). In very severe cases of rib fractures (OR=0.65; 95% CI, 0.43-0.98), the probability of detecting occult pneumothorax was reduced. Among the patients with traumatic occult pneumothorax, 15 patients underwent thoracostomy. Cases of hemothorax (70%; P=0.05), surgery (26.67%; P<0.01), and higher injury severity scores (12.87±7.69; P=0.02) were more common in the thoracostomy group. Conclusion Usually traumatic occult pneumothorax is treated conservatively with regular follow-up, but thoracostomy is necessary when it is accompanied by hemothorax and for patients requiring surgery and having a higher injury severity score.