On July 7, 2010, a 74-year-old man came to our hospital, complaining that he had a nagging pain in his chest that started the preceding day. After performing electrocardiography, blood tests and electrocardiography, we diagnosed the case as acute myocardial infarction. At first, it was thought that blood flow could be restored in due course of time, antiplatelet and anticoagulant agents were used. Intracardiac catheterization was not included in our initial treatment plan. Three days after the initiation of the treatment, the patient had pain in his left inguinocrural region. Computed tomography and magnetic resonance imaging reveled hematoma in his left iliopsoas muscle. We stopped administering antiplatelet and anticoagulant agents to him. But anemia progressed from Hb14.1g/dL to 9.8 g/dL, so blood transfusions had to be given. After that, the patient underwent a rest cure. With the passage of time, the pain and swelling of the left iliopsoas muscle went down. Regarding the cardiac condition, however, the pain in the chest did not abate even when he was taking a rest. The antiplatelet therapy was resumed, with one type of agent given at first and then with another type added. Examinations using a coronary CT and a cadiac catheter found 90% stenosis at the proximal left anterior descending coronary artery. So, a bare metal stent was placed in the near-closed artery. Ever since, there has been no recrudescence of chest pain and no recurrence of iliopsoas muscle hematoma. The extravascated blood mass seemed to be dissolved spontaneously.

In patients with epidermal growth factor receptor (EGFR) mutation-positive lung cancer (LC) who have acquired resistance to first and/or second-generation EGFR-tyrosine kinase inhibitors (EGFR-TKIs), detection of EGFR T790M (T790M) mutation is essential before administration of osimertinib. Tissue sample is the main specimen used to detect the T790M mutation, and so cell block preparation using pleural or pericardial fluid should be considered. The utility of body cavity effusion cell block methods in T790M mutation detection have not yet been fully evaluated. This study aimed to evaluate the clinical background and treatment course of LC patients harboring the T790M mutation by using body cavity effusion cell block methods at our hospital. All patients were treated with first and/or second-generation EGFR-TKIs and had developed malignant pleural or pericardial fluid as a result of progressive disease. T790M mutation status was evaluated using body cavity effusion cell block method in 9 patients, from April 2016 to August 2017. We retrospectively evaluated the clinical characteristics and treatment course of these 9 patients (3 males and 6 females; median age 76 years). At the first diagnosis of LC, 7 patients had stage IV cancer; 4 patients were diagnosed by bronchial fibroscopy and 3 were diagnosed from pleural fluid examination. Regarding EGFR mutation, 3 and 6 patients carried the exon 19 deletion and L858R mutation, respectively. Median time interval between the first diagnosis of LC and T790M mutation evaluation was 30.8 months; 7 patients were diagnosed with positive T790M mutation by using body cavity effusion cell block methods. The T790M mutation was highly detected by examination of body cavity effusion cell blocks. Further evaluation is necessary with respect to variations in T790M detection rate based on the specimen collection site and/or progressive disease pattern in different patients.