Spatial transcriptomics elucidates medulla niche supporting germinal center response in myasthenia gravis-associated thymoma.

Myasthenia gravis (MG) is etiologically associated with thymus abnormalities, but its pathology in the thymus remains unclear. In this study, we attempt to narrow down the features associated with MG using spatial transcriptome analysis of thymoma and thymic hyperplasia samples. We find that the majority of thymomas are constituted by the cortical region. However, the small medullary region is enlarged in seropositive thymomas and contains polygenic enrichment and MG-specific germinal center structures. Neuromuscular medullary thymic epithelial cells, previously identified as MG-specific autoantigen-producing cells, are enriched in the cortico-medullary junction. The medulla is characterized by a specific chemokine pattern and immune cell composition, including migratory dendritic cells and effector regulatory T cells. Similar germinal center structures and immune microenvironments are also observed in the thymic hyperplasia medulla. This study shows that the medulla and junction areas are linked to MG pathology and provides insights into future MG research.

Peritoneal Dissemination in Patients with Recurrence After Post-pleurectomy/decortication for Pleural Mesothelioma.

BACKGROUND: In clinical practice, peritoneal dissemination after curative-intent surgery for pleural mesothelioma occasionally recurs. This study investigated the risk factors and prognosis associated with post-pleurectomy/decortication peritoneal dissemination in pleural mesothelioma, which are rarely reported. METHODS: This retrospective review included 160 patients who experienced recurrence after pleurectomy/decortication for pleural mesothelioma between January 2011 and December 2021. Patients with recurrence were classified according to the initial recurrence pattern. The P group experienced recurrence with peritoneal dissemination, and the non-P group experienced recurrence without peritoneal dissemination. The analysis determined the risk factors for peritoneal dissemination using multivariable logistic regression analysis. Survival was analyzed using the Kaplan-Meier method and the log-rank test. RESULTS: Of the 160 patients, 20 (12.5%) exhibited peritoneal dissemination and were assigned to the P group, whereas 140 (87.5%) had recurrence without peritoneal dissemination and were assigned to the non-P group. Multivariable logistic regression analysis showed that diaphragm reconstruction (odds ratio [OR], 2.8; 95% confidence interval [CI], 1.0-8.0; p = 0.048) and female sex (OR, 3.7; 95% CI 1.26-10.8; p = 0.017) were associated with the P group. Post-recurrence survival was worse in the P group than in the non-P group (1-year post-recurrence survival: 22.2% vs. 65.3%; median: 6.7 months vs. 19.4 months; p = 0.0013). CONCLUSIONS: Peritoneal dissemination occurred in approximately one of every eight patients with recurrence after pleurectomy/decortication for pleural mesothelioma, and the incidence was significantly higher among females and patients undergoing diaphragm reconstruction. Moreover, postoperative recurrence of peritoneal dissemination was associated with a poor prognosis.

Laparoscopically assisted diaphragmatic hernia repair with mesh and a myocutaneous flap after left ventricular assist device explantation: A case report.

We report the case of a 32-year-old man who developed a giant diaphragmatic hernia following the removal of a left ventricular assist device 4 years prior due to improved cardiac function. Chest radiography revealed an intrathoracic prolapse of the gastrointestinal tract. The patient was diagnosed with a diaphragmatic hernia and a laparoscopy-assisted repair was performed. A 12 × 8 cm hernia was found intraoperatively on the left diaphragm, and a large portion of the gastrointestinal tract had prolapsed into the thoracic cavity. We attempted to repair the ventromedial defect using mesh; however, it was found to be insufficient. Therefore, we used a left rectus abdominis myocutaneous flap to fill the defect and sutured it to the mesh. A myocutaneous flap could be a useful strategy in cases where complete closure with mesh is difficult.

ACTN4 is associated with the malignant potential of thymic epithelial tumors through the ß-catenin/Slug pathway.

Thymic epithelial tumors (TETs) are rare tumors arising from the mediastinum. Among TETs, thymoma type B2, B3 and thymic carcinoma are highly malignant and often present invasion and dissemination. However, the biological characteristics of TETs have not been thoroughly studied, and their mechanisms of invasion and dissemination are largely unknown. α-Actinin 4 (ACTN4) is a member of actin-binding proteins and reportedly plays important roles in the progression of several cancers. In this study, we investigated the relationship between ACTN4 and characteristics of the malignant potential of TETs, such as invasion and dissemination. In vitro experiments using Ty-82 thymic carcinoma cells revealed that overexpression of ACTN4 enhanced the proliferative and invasive ability of Ty-82 cells; conversely, knockdown of ACTN4 attenuated the proliferative and invasive potential of Ty-82 cells. In western blotting (WB) experiments, ACTN4 induced the phosphorylation of extracellular signal-regulated kinase and glycogen synthase kinase 3ß to regulate the ß-catenin/Slug pathway. Furthermore, WB analysis of cancer tissue-origin spheroids from patients with TETs showed results similar to those for Ty-82 cells. In vivo experiments showed that the knockdown of ACTN4 significantly suppressed the dissemination of Ty-82 cells. A WB and immunohistochemistry staining comparison of primary and disseminated lesions of TETs using surgical specimens showed upregulated expression of ACTN4, ß-catenin, and Slug proteins in disseminated lesions. In summary, our study suggests ACTN4 is associated with malignant potential characteristics such as invasion and dissemination in TETs via the ß-catenin/Slug pathway.

CD98 heavy chain protein is overexpressed in non-small cell lung cancer and is a potential target for CAR T-cell therapy.

Chimeric antigen receptor (CAR) T cells are effective against hematological cancers, but are less effective against solid tumors such as non-small cell lung cancer (NSCLC). One of the reasons is that only a few cell surface targets specific for NSCLC cells have been identified. Here, we report that CD98 heavy chain (hc) protein is overexpressed on the surface of NSCLC cells and is a potential target for CAR T cells against NSCLC. Screening of over 10,000 mAb clones raised against NSCLC cell lines showed that mAb H2A011 bound to NSCLC cells but not normal lung epithelial cells. H2A011 recognized CD98hc. Although CAR T cells derived from H2A011 could not be established presumably due to the high level of H2A011 reactivity in activated T cells, those derived from the anti-CD98hc mAb R8H283, which had been shown to lack reactivity with CD98hc glycoforms expressed on normal hematopoietic cells and some normal tissues, were successfully developed. R8H283 specifically reacted with NSCLC cells in six of 15 patients. R8H283-derived CAR T cells exerted significant anti-tumor effects in a xenograft NSCLC model in vivo. These results suggest that R8H283 CAR T cells may become a new therapeutic tool for NSCLC, although careful testing for off-tumor reactivity should be performed in the future.

Salvage surgery following tyrosine kinase inhibitor treatment for advanced non-small cell lung cancer.

BACKGROUND: No standard therapy for non-small lung cancer patients that have acquired resistance to tyrosine kinase inhibitor (TKI) therapy has been established. Some can be effectively treated by salvage surgery, though indications for that procedure remain unclear. Reported here is the clinical course of a patient who experienced early post-operative distant metastases. CASE PRESENTATION: A 48-year-old woman without symptoms was referred to another hospital for abnormal chest radiography findings and diagnosed with adenocarcinoma of the left lower lobe (cT2aN3M1b, stage IVB; TNM staging 7th edition). Gene mutation analysis revealed positive for epidermal growth factor receptor exon 19 deletion. Afatinib treatment was started, resulting in partial response, though regrowth of the main tumor was noted 1.5 years later. Bronchoscopic re-biopsy findings revealed a T790M point mutation and afatinib was switched to osimertinib. At 1.5 years following the start of osimertinib administration, the primary tumor was found to have regrown again and stereotactic radiation therapy was administered. Findings at 3.5 years after osimertinib administration indicated that all lymph nodes and distant metastases, excluding the primary tumor, were well controlled, and the patient was referred to our hospital for salvage surgery. Osimertinib was discontinued, and a left lower lobectomy with a left lingular segmentectomy and pleural biopsy were performed. The patient was discharged following an uneventful postoperative course. Three days after discharge, glossodynia developed and examination findings revealed tongue metastasis. The symptoms improved following re-administration of osimertinib, though right adrenal gland metastasis appeared 8 months after surgery. Radiation therapy was performed for tongue and right adrenal gland metastases, and the patient was alive 1 year after salvage surgery without out-of-control lesion appearing after the radiation therapy under the administration of osimertinib. CONCLUSION: The present patient experienced multiple instances of systemic recurrence after undergoing salvage surgery. Experience with this case indicates that systemic therapy is essential for patients with distant metastatic lung cancer even following salvage surgery for the primary tumor.

In situ analysis of CCR8+ regulatory T cells in lung cancer: suppression of GzmB+ CD8+ T cells and prognostic marker implications.

BACKGROUND: CCR8-expressing regulatory T cells (Tregs) are selectively localized within tumors and have gained attention as potent suppressors of anti-tumor immunity. This study focused on CCR8+ Tregs and their interaction with CD8+ T cells in the tumor microenvironment of human lung cancer. We evaluated their spatial distribution impact on CD8+ T cell effector function, specifically granzyme B (GzmB) expression, and clinical outcomes. METHODS: A total of 81 patients with lung squamous cell carcinoma (LSCC) who underwent radical surgical resection without preoperative treatment were enrolled. Histological analyses were performed, utilizing an automated image analysis system for double-stained immunohistochemistry assays of CCR8/Foxp3 and GzmB/CD8. We investigated the association of CCR8+ Tregs and GzmB+ CD8+ T cells in tumor tissues and further evaluated the prognostic impact of their distribution profiles. RESULTS: Histological evaluation using the region of interest (ROI) protocol showed that GzmB expression levels in CD8+ T cells were decreased in areas with high infiltration of CCR8+ Tregs, suggesting a suppressive effect of CCR8+ Tregs on T cell cytotoxicity in the local tumor microenvironment. Analysis of the association with clinical outcomes showed that patients with more CCR8+ Tregs and lower GzmB expression, represented by a low GzmB/CCR8 ratio, had worse progression-free survival. CONCLUSIONS: Our data suggest that local CCR8+ Treg accumulation is associated with reduced CD8+ T cell cytotoxic activity and poor prognosis in LSCC patients, highlighting the biological role and clinical significance of CCR8+ Tregs in the tumor microenvironment. The GzmB/CCR8 ratio may be a useful prognostic factor for future clinical applications in LSCC.

Expression of fibroblast activation protein in intrathoracic solitary fibrous tumor.

PURPOSE: Fibroblast activation protein (FAP) is a serine integral membrane protease, the expression of which has been confirmed in various cancer types. Solitary fibrous tumors of the pleura (SFTP) are rare mesenchymal fibroblastic neoplasms. We present a case of 18F-labeled FAP inhibitor ([18F]FAPI-74) PET imaging and its correlation with histological FAP expression and review an SFTP series at our institution in relation to the extent of FAP expression. METHODS: This retrospective study included 13 patients who underwent surgery between March 2011 and December 2022 at our institute. One of the patients also underwent [18F]FAPI-74 PET imaging. We semi-quantitatively evaluated FAP expression in SFTPs using immunohistochemical staining and H-scores. RESULTS: Nine of the 13 patients were male, with a median age of 64 years (range, 28-79 years). The median tumor size was 6.6 cm (1.1, 16 cm). In the pathological findings, expression levels of Ki67 were 1-5% in 12 of 13 cases. Furthermore, FAP expression was observed in all patients, and the median H-score was 160 (range, 10-280). The H-score of FAP expression in two of the 13 patients was low (10 in both), and that in two of the 13 patients was high (240 and 280). The SUVmax value of [18F]FAPI-74 PET was 3.57 in a patient in whom the H-score of FAP expression was 180. CONCLUSIONS: SFTPs expressed FAP to varying degrees in different patients and the [18F]FAPI-74 PET results in one patient reflected FAP expression in the tumor tissue.

Effect of mTOR inhibitors on the mortality and safety of patients with lymphangioleiomyomatosis on the lung transplantation waitlist: A retrospective cohort study.

BACKGROUND: Although lung transplantation (LTx) is the last resort for patients with end-stage lymphangioleiomyomatosis (LAM), the high waitlist mortality is a source of concern in Japan. Discontinuation of mechanistic target of rapamycin (mTOR) inhibitors prior to LTx is recommended due to the incidence of severe adverse events. Therefore, we hypothesized that mTOR inhibitors may affect the mortality of patients with LAM on the LTx waitlist. METHODS: We retrospectively compared the characteristics of consecutive patients with LAM on the LTx waitlist who were and were not receiving mTOR inhibitors. RESULTS: Twenty-nine consecutive patients with LAM who listed our center between January 2004 and December 2021 were selected from the database and enrolled in the present study. Seventeen patients (58.6%) were receiving a mTOR inhibitor, sirolimus (treatment group). During a median listing period of 1277 days, 12 patients (41.4%) were hospitalized, six patients (20.7%) died from disease before LTx, and 15 patients underwent LTx. Among the deceased patients, four patients (66.6%) had pneumothoraces. The waitlist mortality in the treatment group was significantly lower than that in the non-treatment group (p = 0.03). Among the six patients who discontinued sirolimus in the treatment group, four patients (66.6%) were hospitalized with respiratory complications after the discontinuation of sirolimus. No mTOR inhibitor-related complications arose in the treatment group undergoing LTx (n = 7), including those on a reduced sirolimus dose. CONCLUSIONS: Administration of an mTOR inhibitor until LTx may decrease waitlist mortality. Due to life-threatening events after discontinuing sirolimus pre-LTx, a reduced dose until LTx is permissible.

Surgical resection of advanced intrathoracic tumors through a combination of the hemiclamshell and transmanubrial approaches.

PURPOSE: The hemiclamshell (HCS) approach provides a comprehensive view of the anterior mediastinum, whereas the transmanubrial osteomuscular sparing approach (TMA) allows sufficient exposure of the cervico-thoracic transition. We assessed the effectiveness and the outcomes of the combined HCS plus TMA approach to resect thoracic malignant tumors. METHODS: We reviewed five patients with thoracic malignant tumors invading the thoracic outlet who underwent surgery using an HCS and TMA approach between 2018 and 2021. RESULTS: The preoperative diagnosis was myxofibrosarcoma, lung cancer, thymic cancer, thymoma, and neurofibromatosis type1 in one patient each, respectively. Cardiovascular reconstruction was done on the aortic arch in two patients, on the descending aorta in one, and on the superior vena cava in one, combined with resection of the vagus nerve in three patients, of the phrenic nerve in two, and of vertebra in one, with overlap in some cases. The TMA was added because all patients required dissection of the periphery of the subclavian artery, and two had tumor extension to the neck. Macroscopic complete resection was achieved in four patients. There was no postoperative mortality. CONCLUSION: The combination of the HCS and TMA approaches at the same operation provides a comprehensive view of the mediastinum, lung, and cervico-thoracic transition and allows safe access to the thoracic great vessels and subclavian vessels.

Native lung surgery after single lung transplantation: clinical characteristics and outcomes.

PURPOSE: Single lung transplantation (SLT) is a viable option for patients with end-stage pulmonary parenchymal and vascular diseases. However, various diseases can occur in native lungs after SLT. METHODS: Between January 2000 and December 2021, 35 patients underwent cadaveric SLT and survived for more than 30 days in our hospital. Among these 35 patients, 10 required surgery for diseases that developed in their native lungs. The clinical characteristics of these 10 patients and the outcomes of native lung surgery (NLS) were investigated. RESULTS: Among these ten patients, the indications for lung transplantation were chronic obstructive pulmonary disease and idiopathic interstitial pneumonia in three patients each, and lymphangioleiomyomatosis and collagen vascular disease-related interstitial pneumoniain two patients each. The causes of NLS included pneumothorax (n = 4), primary lung cancer (n = 2), native lung hyperinflation (n = 2), and pulmonary aspergilloma (n = 2). The surgical procedures were pneumonectomy (n = 7), lobectomy (n = 2), and alveolar-pleural fistula repair (n = 1). Only one postoperative complication, empyema, was treated with antibiotics. The 5-year overall survival rates after transplantation with and without NLS were 70.0% and 80.0%, respectively, and did not differ to a statistically extent (p = 0.56). CONCLUSION: NLS is an effective treatment option for diseases that develop in the native lungs after SLT.

Surgery for pulmonary lesions in patients with a history of urinary tract transitional cell carcinoma.

BACKGROUND: There has been little information on the actual diagnosis of pulmonary lesions in patients with a history of urinary tract transitional cell carcinoma (TCC) and short- and long- outcomes of pulmonary resection for these patients. METHODS: In the present study, the data of 37 consecutive patients with a history of TCC who underwent pulmonary resection for solitary pulmonary lesions were reviewed, and the clinical factors and short- and long-term outcomes were analyzed. RESULTS: The study population included 35 male patients, and 2 female patients. The mean age was 72.5 years. Twenty patients (80%) were smokers and showed a high incidence of chronic obstructive pulmonary disease. Pulmonary lesions and primary TCC were detected simultaneously in 5 patients and metachronously in 32 patients. The median interval between treatment for primary TCC and the detection of pulmonary lesion was 43 months. The mean tumor diameter was 23 mm. The types of resection included lobectomy (n = 19), segmentectomy (n = 8), and partial resection (n = 10). Twelve of 37 patients (32%) developed postoperative complications. The pathological diagnoses included primary lung cancer (n = 28), pulmonary metastasis from TCC (n = 7), and others (n = 2). The 5-year overall survival rate for all patients was 72%. The 5-year overall survival rate of patients with primary lung cancer was 74%, while that of patients with pulmonary metastasis from TCC was 57%. CONCLUSIONS: Surgery can be proactively considered for treating pulmonary lesions in patients with a previous history of TCC, as it provides favorable long-term outcomes.

A Novel Peroxisome Proliferator-Activated Receptor Gamma/Nuclear Factor-Kappa B Activation Pathway is Involved in the Protective Effect of Adipose-Derived Mesenchymal Stem Cells Against Ischemia-Reperfusion Lung Injury.

BACKGROUND: Adipose-derived stem cells (ADSCs) are well-recognized for their remarkable ability to suppress ischemia-reperfusion lung injury (IRLI). The primary objective of this investigation was to elucidate the underlying mechanism through which ADSCs exert protective effects against IRLI. METHODS: A warm hilar occlusion model in C57BL6J mice was used. Hilar occlusion was achieved for 1 hour (ischemic), and after 1 hour the occlusion was released (reperfusion) to recover for 3 hours. RNA sequencing, the physiological function, pathway activation, and expression of inflammatory cytokines were evaluated. RESULTS: Lung gas exchange and pulmonary edema were significantly improved in the IRLI/ADSCs group compared with the IRLI group. RNA sequencing results suggested that the peroxisome proliferator-activated receptor gamma (PPARγ)/nuclear factor-kappa B (NF-κB) pathway was involved in the effect of the ADSCs. Administration of a PPARγ antagonist in the IRLI/ADSC group resulted in the deterioration of the physiological function. Furthermore, the PPARγ protein expression level decreased, the NF-κB protein expression level increased, and inflammatory cytokine parameters from lung tissue and blood sample worsened in the PPARγ antagonist-administered group. CONCLUSION: Administration of ADSCs exerted a significant protective effect against IRLI in mice, and the effect is attributed to the activation of the PPARγ/NF-κB pathway.

Familial multiple endocrine neoplasia type 1 with intrathoracic low-grade fibromyxoid sarcoma.

BACKGROUND: Multiple endocrine neoplasia type 1 (MEN1) is a hereditary tumor syndrome characterized by endocrine tumors with mainly a parathyroid, pancreatic, or anterior pituitary origin. Low-grade fibromyxoid sarcoma (LGFMS) is a rare low-grade soft tissue tumor. There is one known report of a patient with MEN1 complicated by LGFMS, which is very rare. Our report represents the second documented case, providing valuable insights. CASE PRESENTATION: A 31-year-old man with the chief complaint of a cough underwent chest contrast-enhanced computed tomography, which revealed a giant hypoabsorptive tumor with a maximum diameter of 23 cm in the left thoracic cavity. The patient was diagnosed with MEN1, as he also possessed a pancreatic neuroendocrine tumor and parathyroid tumor, and because his father had been found to have MEN1. To control hypercalcemia, surgery for the parathyroid tumor was initially performed, followed by surgical resection of the giant thoracic tumor for diagnosis and treatment. Histopathological examination findings of the tumor resulted in a diagnosis of LGFMS. CONCLUSION: We experienced a very rare MEN1 with LGFMS. Although endocrine tumors generally occur more frequently in MEN1, non-endocrine tumors such as the present case should also be noted, reinforcing the importance of systemic imaging scrutiny in addition to early diagnosis and long-term follow-up of MEN1 patients.

Association of the psoas muscle index with the survival of patients on a waiting list for lung transplantation: a Japanese single-institution study.

PURPOSES: Some predictive markers of death have been reported for patients on the waiting list for lung transplantation (LTx). We assessed whether or not the preoperative psoas muscle index (PMI) correlates with waitlist mortality. METHODS: In 81 patients with end-stage lung disease on the waiting list for LTx between 2011 and 2020 at Osaka University Hospital, we examined the association between baseline characteristics, including the diagnosis, respiratory function test results, blood collection items, steroid use, and psoas muscle mass on computed tomography, and survival during the waiting period using Kaplan-Meier curves and Cox proportional hazard regression models. RESULTS: Thirty-three patients (41%) died during follow-up. Univariate and multivariate analyses showed that patients with a low PMI had a higher rate of death during follow-up than those with a high PMI (p < 0.0001 and 0.0002, respectively). In addition, a diagnosis of interstitial pneumonia (hazard ratio 3.30, 95% confidence interval 1.52-7.17, p = 0.0025) and low albumin level (hazard ratio 2.21, 95% confidence interval 1.02-4.80, p = 0.0449) were also significant predictors of survival. CONCLUSION: A low PMI at registration is associated with a decreased survival time among LTx candidates and it may be a predictive factor of mortality in patients waiting for LTx.

Integrated cardiothoracic team approach for complex lung transplantation procedures in Japan-current status and future direction.

The first lung transplant procedure in the world was performed in 1983, while in Japan that was first accomplished in 1998. Over the following 25 years, lung transplantation has become a viable treatment option for Japanese patients with a variety of end-stage lung diseases. Seventy cadaveric-donor lung (41 single, 29 bilateral), 11 bilateral living-donor lobar lung, and three heart-lung transplants have been performed with use of an integrated cardiothoracic team approach at medical facilities associated with Osaka University. Extremely advanced clinical and surgical skill sets are required to complete a lung transplant procedure, including surgical knowledge and techniques, as well as management of cardiovascular surgery, especially in regard to mechanical circulatory support (MCS), vascular anastomosis in difficult cases, and concomitant cardiac surgery. We have found that a collaborative effort by general thoracic and cardiac surgeons is an important key for success with lung transplantation. Complex lung transplant surgery and management in Japan are performed by use of an integrated cardiothoracic team approach, which has led to a synergistic impact on successful lung transplantation cases by capitalizing greatly on the experiences, techniques, and expertise of cardiac and thoracic experts. The present review is focused on the role of cardiac surgeons from the viewpoint of our experience with these cases.

Evaluation of LAT1 Expression in Patients With Lung Cancer and Mediastinal Tumors: 18F-FBPA PET Study With Immunohistological Comparison.

PURPOSE OF THE REPORT: L-type amino acid transporter-1 (LAT1) is a tumor-specific transporter expressed in various tumor types, with minimal expression in normal organs. We previously demonstrated 18F-fluoro-borono-phenylalanine (18F-FBPA) as a selective PET probe for LAT1 in a preclinical study. Herein, we evaluated LAT1 expression in preoperative patients with lung or mediastinal tumors using 18F-FBPA PET and immunofluorescence staining. PATIENTS AND METHODS: The study population included patients with histopathological diagnosis (n = 55): primary lung cancers (n = 21), lung metastases (n = 6), mediastinal tumors (n = 15), and benign lesion (n = 13). PET scanning was performed 1 hour after the injection of 18F-FBPA (232 ± 32 MBq). Immunofluorescence staining was performed on the resected tumor sections using LAT1 antibody. LAT1 staining was graded on a 4-grade scale and compared with the SUVmax on 18F-FBPA PET. RESULTS: A positive correlation was observed between the SUVmax of 18F-FBPA PET and LAT1 expression by immunofluorescence staining (r = 0.611, P < 0.001). The SUVmax of 18F-FBPA was 3.92 ± 1.46 in grade 3, 3.21 ± 1.82 in grade 2, 2.33 ± 0.93 in grade 1, and 1.50 ± 0.39 in grade 0 of LAT1 expression. Although 18F-FBPA PET showed variable uptake in lung cancers and mediastinal tumors, benign lesions showed significantly lower SUVmax than those in malignant lesions (P < 0.01). CONCLUSIONS: Uptake on 18F-FBPA PET reflected the expression level of LAT1 in lung and mediastinal tumors. It was suggested that 18F-FBPA PET can be used for the precise characterization of the tumor in pretreatment evaluation.

A case of alpha-fetoprotein-positive thymic small cell carcinoma: a case report.

BACKGROUND: An alpha-fetoprotein (AFP)-positive neuroendocrine tumor of the thymus is a rare thoracic malignancy. Few cases of AFP-positive thymic large cell neuroendocrine carcinoma have been reported, with no known previous report of an AFP-positive thymic small cell carcinoma. We encountered a patient with an AFP-positive small cell carcinoma and report here the clinical course. CASE PRESENTATION: A 40-year-old man was transferred to our hospital for a large anterior mediastinal tumor and showed an elevated serum AFP level. Computed tomography-guided biopsy results led to diagnosis of small cell carcinoma. Induction chemoradiotherapy was performed before surgery because of pulmonary artery invasion. The response to Induction chemoradiotherapy varied among sites, with the main tumor showing shrinkage and the metastasis site growth. This discrepancy suggested a histologic type unresponsive to or cancer cells potentially resistant to chemotherapy, thus a surgical re-biopsy was performed and histological findings revealed AFP-positive small cell carcinoma. Additional chemotherapy was performed, though could not control cancer progression, and the patient died 8 months after the first medical examination. CONCLUSIONS: Our present clinical experience indicates the importance of histological examination for determining AFP-positive anterior mediastinal tumor treatment. Although AFP-positive neuroendocrine tumor of the thymus is relatively rarer than germ cell carcinoma, differential diagnosis with use of a histological examination should be considered because of the potentially poorer prognosis. The present clinical findings for an AFP-positive neuroendocrine tumor of the thymus case are considered useful for establishing an optimal treatment strategy in the future.