Background Epidermal growth factor receptor (EGFR) gene mutation testing is crucial for the administration of tyrosine kinase inhibitors to treat non–small cell lung cancer. In addition to traditional tissue-based tests, liquid biopsies using plasma are increasingly utilized, particularly for detecting T790M mutations. This study compared tissue- and plasma-based EGFR testing methods.
Methods A total of 248 patients were tested for EGFR mutations using tissue and plasma samples from 2018 to 2023 at Pusan National University Yangsan Hospital. Tissue tests were performed using PANAmutyper, and plasma tests were performed using the Cobas EGFR Mutation Test v2.
Results All 248 patients underwent tissue-based EGFR testing, and 245 (98.8%) showed positive results. Of the 408 plasma tests, 237 (58.1%) were positive. For the T790M mutation, tissue biopsies were performed 87 times in 69 patients, and 30 positive cases (38.6%) were detected. Plasma testing for the T790M mutation was conducted 333 times in 207 patients, yielding 62 positive results (18.6%). Of these, 57 (27.5%) were confirmed to have the mutation via plasma testing. Combined tissue and plasma tests for the T790M mutation were positive in nine patients (13.4%), while 17 (25.4%) were positive in tissue only and 12 (17.9%) in plasma only. This mutation was not detected in 28 patients (43.3%).
Conclusions Although the tissue- and plasma-based tests showed a sensitivity of 37.3% and 32.8%, respectively, combined testing increased the detection rate to 56.7%. Thus, neither test demonstrated superiority, rather, they were complementary.
Testicular carcinoid tumors are very rare, accounting for less than 1% of all testicular tumors. We report a rare case of a testicular carcinoid tumor with extensive lymphatic invasion. A 42-year-old man presented with a painless, enlarged right testicular mass. There was no history of injury or discomfort in this region. Right radical orchiectomy was performed, which showed a well-defined, non-encapsulated solid white mass with calcification (7.0 × 4.5 × 3.5 cm) and absence of cystic components. Microscopic examination using hematoxylin and eosin staining of the tumor sections identified organoid, trabecular, and solid patterns with rosette formation. Extensive multifocal lymphatic invasion was observed. Immunohistochemistry was positive for synaptophysin, chromogranin, and CD56. Testicular carcinoid tumors usually show good prognoses; however, there was extensive lymphovascular invasion in this case. Thus, in the case of unusual presentation of the disease, close follow-up is necessary.
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