A 66-year-old man was initially suspected of having a microcystic serous cystic neoplasm based on magnetic resonance imaging findings of a multifocal mass measuring 46 mm in the pancreatic head, with a cystic component showing a high signal on T2-weighted images. The tumor marker levels were within normal limits. However, contrast-enhanced computed tomography revealed thick cyst walls with delayed staining, which was atypical for serous cystic neoplasms; therefore, the patient was followed up closely. Twenty-two months later, the delayed contrast area was enlarged, carbohydrate antigen 19-9 levels were elevated, and 18 F-fluorodeoxyglucose-positron emission tomography revealed increased accumulation, indicating a potentially malignant lesion. Pancreatoduodenectomy was performed and histopathological examination confirmed the diagnosis of normal-type pancreatic carcinoma with predominantly poorly differentiated cells. Based on the pathological findings and a literature review, it is highly likely that this case represents pancreatic ductal adenocarcinoma with a cystic structure from the beginning. While distinguishing pancreatic ductal adenocarcinoma from other pancreatic cystic tumors, such as serous cystic neoplasms, is critical owing to differing treatments and prognoses, caution is warranted as they may exhibit similar imaging features, as observed in our patient.

A 74-year-old man underwent a distal gastrectomy for advanced gastric cancer. After surgical treatment, lymph node metastasis was observed during postoperative adjuvant S-1 chemotherapy. Weekly PTX plus RAM as second-line therapy and nivolumab as third-line therapy was administered, but lymph node enlarged and CA19-9 remained high. Therefore, 6 courses of CapeOX was administered as the fourth-line therapy, and CA19-9 markedly decreased and normalized, and CT showed marked reduction in all lymph nodes. After 12 courses, CT scan showed lymph node shrinkage and PET-CT scan showed no FDG uptake, and the patient was diagnosed as clinical complete response(cCR). Six months later, maintaining cCR. We experienced a case in which the introduction of CapeOX therapy resulted in a remarkable response to recurrence of lymph nodes after gastric cancer during S-1 therapy.

A 63-year-old man was admitted to a hospital owing to shortness of breath. He was diagnosed as having gastric cancer with pulmonary carcinomatous lymphangitis(PCL)and disseminated carcinomatosis of the bone marrow(DCBM). Regarding tumor markers, carcinoembryonic antigen(CEA)and carbohydrate antigen 19-9(CA19-9)levels increased to 332 ng/ mL and 921 U/mL, respectively. Since the disease was also accompanied by disseminated intravascular coagulation(DIC), S- 1 plus cisplatin chemotherapy was started immediately(S-1 120 mg/body administered for 21 days and cisplatin 60 mg/m2 administered on day 8, 35 days for a course). Approximately 2 weeks after the initiation of chemotherapy, the patient\'s respiratory symptoms improved, and he recovered from DIC. After 2 chemotherapy courses, tumor marker levels decreased (CEA 9.3 ng/mL and CA19-9 314 U/mL), and the patient continued to receive chemotherapy without the deterioration of his physical condition for 5 months. However, he experienced fatigue after 4 courses, because of the progression of gastric cancer. Although the regimen was changed to ramucirumab plus paclitaxel chemotherapy, the patient died 8 months after the initiation of chemotherapy. An accumulation of cases is needed to establish treatment strategies for gastric cancer with PCL and/or DCBM.

BACKGROUND: Carbohydrate antigen 19-9 (CA19-9) is usually synthesized by pancreatic and bile duct cells and is present in small amounts in serum. During the period of tumor disease, its serum level significantly increases, and it is the most widely used serum tumor marker for diagnosis and monitoring therapy of pancreatic cancer.
METHODS: We reported a case of abnormal elevation of serum CA19-9. Considering the possibility of detection interference, we used heterophilic antibody blocking analysis, detection by different analysis systems, and polyethylene glycol (PEG) precipitation to evaluate the reliability of abnormally elevated CA19-9 concentration.
RESULTS: Repeated measurements on the Roche Cobas 8000 system of another hospital significantly reduced the CA19-9 concentration, as did PEG precipitation. Therefore, the abnormally elevated level of CA19-9 in this patient is considered to be pseudoelevation caused by interferences.
CONCLUSIONS: We suggest considering the presence of detection interference in cases with elevated CA19-9 levels but no related clinical manifestations to prevent false positives. PEG precipitation may be a simple and feasible solution to eliminate interference.

An 80-year-old man with jaundice and fatigue was referred to our hospital. A laboratory examination revealed increased levels of hepatobiliary enzymes, and CA19-9 levels increased to 29,512 U/mL. Based on the findings of imaging examination and laboratory data, the patient was diagnosed with acute cholecystitis and choledocholithiasis. The possibility of malignancy could not be ruled out because of the high levels of CA19-9. Antibiotic administration was commenced, and the common bile duct stone was endoscopically removed. One month after treatment, the CA19-9 level decreased to within the normal range. One year after treatment, imaging examinations did not reveal any malignancy.

Pulmonary sequestration is a rare congenital condition. It is a dysplastic lung tissue with a separate systemic blood supply and without a bronchial tree connection. The emergence of a superimposed infection can lead to its diagnosis, such as Staphylococcus aureus, Pseudomonas aeruginosa, Nocardia asteroids and Aspergillus sp pneumonia. Mycobacterium avium complex (MAC) superimposed disease is exceedingly rare. We report a case of a man in his third decade without known medical disorders presenting with a persistent cough. After an extensive microbiological workup, an MAC infection was diagnosed. An elevated carbohydrate antigen 19-9 (CA 19-9) was also noted. He was treated with antimycobacterial therapy and lobectomy resulting in clinical improvement and CA19-9 normalisation. This case illustrates the value of comprehensive microbiological investigations in patients with chronic respiratory symptoms and imaging findings that are not typical of bacterial pneumonia. Clinical studies remain needed to investigate the utility of CA 19-9 in a scoring system to guide MAC therapy.

We report an autopsy case of a large duodenal adenocarcinoma that produced alpha-fetoprotein (AFP). The patient was a man in his 70s with diabetes mellitus. He presented with epigastralgia and was referred to our hospital. Upper gastrointestinal endoscopy and abdominal computed tomography revealed a large tumor of 11 cm in diameter in the descending limb of the duodenum. A tumor biopsy showed poorly differentiated adenocarcinoma. Although his carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) levels were within the normal range, his AFP levels were significantly elevated (42,078.4 ng/mL). Due to vascular invasion, curative resection was not feasible, and chemotherapy was chosen as the treatment option. After gastrojejunostomy was performed to enable oral intake, one cycle of modified leucovorin/5-fluorouracil/oxaliplatin (mFOLFOX6) therapy was administered. However, it proved ineffective, and the patient\'s anorexia gradually worsened. Ultimately, he succumbed to the progression of cancer cachexia. Autopsy findings revealed a 14-cm-long duodenal carcinoma primarily located in the duodenal bulb, with direct invasion into the stomach, pancreas, and liver. A pathological examination confirmed a diagnosis of poorly differentiated adenocarcinoma with AFP production. Duodenal cancer is rare, and AFP-producing duodenal cancer is even rarer, with only 21 reported cases, including our own. We present this autopsy case of AFP-producing duodenal adenocarcinoma and review the cases reported in the relevant literature.

BACKGROUND: Pathological examination by endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA) has been reported to be useful in diagnosing pancreatic malignant lymphoma (ML), but some ML cases are difficult to be differentiated from pancreatic ductal adenocarcinoma (PDAC).
METHODS: This retrospective study included 8 patients diagnosed with ML that had a pancreatic-head lesion at initial diagnosis and 46 patients with resected PDAC in the pancreatic head between April 2006 and October 2021 at our institute. ML and PDAC were compared in terms of patients\' clinical features and imaging examinations.
RESULTS: The median tumor size was larger in ML than in PDAC (45.8 [24-64] vs. 23.9 [8-44] mm), but the median diameter of the caudal main pancreatic duct (MPD) was larger in PDAC (2.5 [1.0-3.5] vs. 7.1 [2.5-11.8] mm), both showing significant differences between these malignancies (both, P < 0.001). In the analysis of covariance, MLs showed a smaller caudal MPD per tumor size than PDACs, with a statistical difference (P = 0.042). Sensitivity and specificity using sIL-2R ≥ 658 U/mL plus CA19-9 < 37 U/mL for the differentiation of ML from PDAC were 80.0% and 95.6%, respectively.
CONCLUSIONS: Diagnosing pancreatic ML using cytohistological examination through EUS-FNA can be difficult in some cases. Thus, ML should be suspected if a patient with a pancreatic tumor has a small MPD diameter per tumor size, high serum sIL-2R level, normal CA19-9 level. If the abovementioned features are present and still cannot be confirmed as PDAC, re-examination should be considered.

We report a case of an elderly patient, 82 years-old, with initially-unresectable pancreatic head cancer, who successfully underwent complete resection of the primary lesion after systemic chemotherapy for 6 months. The patient had a history of pancreatic body-tail resection for intraductal papillary mucinous carcinoma in 2005. In 2020, a routine examination revealed an increased CA19-9 value of 1,958 U/mL and showed a pancreatic head tumor of 35 mm on CT images. Finally, the tumor was pathologically diagnosed as pancreatic cancer by a biopsied sample. Although CT images showed no distant metastasis, peritoneal lavage cytology was indicated as positivity(H0P0CY1)in the staging laparoscopy. We implanted a peritoneal port and introduced systemic chemotherapy of gemcitabine and nab-paclitaxel combination therapy. This treatment for 6 months induced tumor shrinkage to 30 mm on the CT image, normalized CA19-9 value to 22.6 U/mL, and negative cytology in the collected lavage fluid from the peritoneal port. The patient\'s general condition was maintained even after the chemotherapy and the lavage cytology was pathologically diagnosed as negative(H0P0CY0)in the repeated staging laparoscopy, therefore we decided to perform pancreaticoduodenectomy as a conversion surgery. The patient was discharged on the 21st postoperative day with an uneventful course and underwent adjuvant chemotherapy of S-1 for 6 months. No recurrence was found in 8 months after the surgery. In such a case of the selected elderly patient with a maintained general condition, it is feasible to undergo multimodal treatments including conversion surgery for an initially-unresectable pancreatic cancer with positive peritoneal cytology.

BACKGROUND: We described a patient who exhibited a gradual increase in carbohydrate antigen 19-9 (CA19-9) concentrations for 4 years at three hospitals, with no associated clinical manifestations; however, we were unable to define the cause of this increase, forcing us to consider whether it was a false-positive result.
METHODS: Given the potential for interference, this study used multiple system detection, gradient dilution, Polyethylene glycol (PEG) precipitation and heterophilic antibody blocking assay to evaluate the reliability of CA19-9 concentration increase.
RESULTS: Analysis of the patient sample using multiple systems indicated that CA19-9 concentrations showed an obvious increase (154.0, and 889.2 IU/ml, respectively) using the Cobas E602 and Advia Centaur XP systems, and were within the reference ranges (<10 IU/ml) on other modules. PEG precipitation on the Cobas E602 and Advia Centaur XP systems reduced the CA19-9 concentration, as did heterophilic blocking tube (HBT-6, HBT-1) blockade.
CONCLUSIONS: CA19-9 was incorrectly identified to increase due to the presence of heterophilic antibodies. We recommend that heterophilic antibodies should be evaluated in cases with elevated CA19-9 level but no associated clinical manifestations to prevent false positives.