Clinical outcomes of sentinel node navigation surgery in patients with preoperatively estimated stage IA endometrial cancer and evaluation of validity for continuing sentinel node navigation surgery based on dispersion of recurrence probability.

BACKGROUND: To evaluate the feasibility of the use and continuation of sentinel lymph node navigation surgery (SNNS) as an alternative to pelvic lymph node dissection (PLND) for patients with preoperatively estimated stage IA endometrial cancer. METHODS: This retrospective study selected the electronic medical records of all patients who had received CT scans and MRI imaging before surgery from April 1, 2009 to March 31, 2021. Sentinel lymph nodes (SLNs) were detected by administrating 99mTc-phytate and/or indocyanine green into the cervix, and the clinical outcomes of the patients who underwent SNNS or PLND were evaluated. Furthermore, in case of nodal recurrence, a new procedure to determine whether the facility should continue with SNNS or not was developed that compares the maximum likelihood hypothesis and an alternative one based on recurrence rates. RESULTS: Among 137 patients, SLN biopsies with ultrastaging were performed on 91 patients. The SLN detection rate was 95.6%. Over a 59-month median observation period, no statistically significant differences were shown in overall survival, disease-specific survival and disease-free survival between the SNNS and PLND groups when introducing the propensity score method (p-values: 0.06, 0.153, and 0.625, respectively). Our procedure demonstrated that, in our department without recurrence up to the 65th attempt, it was possible to continue SNNS if a recurrence occurs at the 66th attempt. CONCLUSION: This study suggests the validity of SNNS as an alternative to PLND. Even in the absence of evidence from randomized controlled trials, we can confirm the validity of continuing SNNS using our procedure.

Hybrid robot-assisted abdominoperineal resection supported by simultaneous trans-perineal approach for anal gland adenocarcinoma with vaginal invasion: a case report.

Hybrid surgery (abdominal robotic approach with a trans-anal approach) has been reported to improve oncological outcomes in cases involving advanced cancer or technical difficulties. A 74-year-old woman presented with anal pain and stenosis. Examination revealed palpable sclerosis on the anterior wall at the anal verge with possible vaginal invasion. A biopsy revealed an adenocarcinoma. We performed a two-team robot-assisted abdominoperineal resection combined with resection of the vagina supported by a simultaneous trans-perineal approach. After rendezvous at the posterior side, the abdominal team cut the posterior wall of the vaginal vault while the perineal team confirmed the surgical margin. Histopathological findings identified the tumour as an anal gland adenocarcinoma (pT4b [vagina] N0M0 pathological stage IIC) with a negative circumferential resection margin. Hybrid surgery combined with resection of the posterior wall of the vagina may be performed safely and is a valuable surgical option for multimodal treatment of anal adenocarcinomas.

Tumor-Infiltrating CD8-Positive T-Cells Associated with MMR and p53 Protein Expression Can Stratify Endometrial Carcinoma for Prognosis.

BACKGROUND: Inspired by the molecular classification of endometrial carcinoma (EC) proposed by The Cancer Genome Atlas Research Network (TCGA), we investigated tumor-infiltrating CD8-positive T-cell as well as DNA mismatch repair (MMR) protein and p53 protein expression, and we developed a new classification system for ECs to predict patients' prognosis using immunohistochemical methods. METHODS: The study included 128 patients with ECs who underwent surgery. Paraffin-embedded tissue sections of the tumor were stained using antibodies against MMR protein, p53, and CD8. Cases were stratified into four classes by a sequential algorithm. An immunohistochemical classification system for ECs (ICEC) was created, including HCD8, MMR-D, LCD8, and p53 LCD8. RESULTS: In ICEC, 16 cases (12.5%), 27 cases (21.09%), 67 cases (52.34%), and 18 cases (14.06%) belonged to HCD8, MMR-D, LCD8, and p53 LCD8, respectively. ICEC did not show any correlation with clinical stage, lymphovascular space invasion, or lymph node metastasis. However, the p53 LCD8 class contained a significantly higher proportion of G3 ECs and serous carcinoma (p < 0.0001). ICEC showed prognostic significance in overall survival (OS) (p < 0.0001) and disease-free survival (DFS) (p < 0.0001). The class of p53 LCD8 showed the worst prognosis among the classes. CONCLUSIONS: ICEC classification is useful in predicting the prognosis of ECs.

Development of a micronucleus test using the EpiAirway™ organotypic human airway model.

BACKGROUND: The use of organotypic human tissue models in genotoxicity has increased as an alternative to animal testing. Genotoxicity is generally examined using a battery of in vitro assays such as Ames and micronucleus (MN) tests that cover gene mutations and structural and numerical chromosome aberrations. At the 7th International Workshop on Genotoxicity Testing, working group members agreed that the skin models have reached an advanced stage of maturity, while further efforts in liver and airway models are needed [Pfuhler et al., Mutat. Res. 850-851 (2020) 503135]. Organotypic human airway model is composed of fully differentiated and functional respiratory epithelium. However, because cell proliferation in organotypic airway models is thought to be less active, assessing their MN-inducing potential is an issue, even in the cytokinesis-blocking approach using cytochalasin B (CB) [Wang et al., Environ. Mol. Mutagen. 62 (2021) 306-318]. Here, we developed a MN test using EpiAirway™ in which epidermal growth factor (EGF) was included as a stimulant of cell division. RESULTS: By incubating EpiAirway™ tissue with medium containing various concentrations of CB, we found that the percentage of binucleated cells (%BNCs) almost plateaued at 3 µg/mL CB for 72 h incubation. Additionally, we confirmed that EGF stimulation with CB incubation produced an additional increase in %BNCs with a peak at 5 ng/mL EGF. Transepithelial electrical resistance measurement and tissue histology revealed that CB incubation caused the reduced barrier integrity and cyst formation in EpiAirway™. Adenylate kinase assay confirmed that the cytotoxicity increased with each day of culture in the CB incubation period with EGF stimulation. These results indicated that chemical treatment should be conducted prior to CB incubation. Under these experimental conditions, it was confirmed that the frequency of micronucleated cells was dose-dependently increased by apical applications of two clastogens, mitomycin C and methyl methanesulfonate, and an aneugen, colchicine, at the subcytotoxic concentrations assessed in %BNCs. CONCLUSIONS: Well-studied genotoxicants demonstrated capability in an organotypic human airway model as a MN test system. For further utilization, investigations of aerosol exposure, repeating exposure protocol, and metabolic activation are required.

Autoimmune Pulmonary Alveolar Proteinosis during the Treatment of Idiopathic Inflammatory Myopathy.

Approximately 50% of idiopathic inflammatory myopathies (IIMs) are associated with interstitial lung disease (ILD). Typically, IIM-ILD manifests as nonspecific interstitial pneumonia. We herein report a rare case of a 78-year-old man with autoimmune pulmonary alveolar proteinosis (PAP) that developed during IIM treatment. The diagnosis of autoimmune PAP was based on detecting anti-granulocyte-macrophage colony-stimulating factor antibodies. We postulated that PAP may have been induced by IIM treatment with prednisolone. Our case suggests that the possibility of autoimmune PAP should be considered in patients with lung lesions during the clinical course of IIM.

Hepatocellular Carcinoma Rupture after Introducing Lenvatinib: An Autopsy Case Report.

Hepatocellular carcinoma (HCC) hemorrhaging/rupture is a rare adverse effect of lenvatinib, and only limited pathological examinations have been reported. This report presents the case of a 69-year-old man who suffered from cardiac arrest and died 7 days after starting lenvatinib treatment for HCC, with an autopsy subsequently performed. Crack and coagulated blood were observed in the largest tumor. Pathologically, the hemorrhaging area was scattered in nearly all of the HCC lesions, regardless of tumor differentiation. This pathological feature is unusual in normal HCC. Thus, it is believed to have been the effect of lenvatinib.

Androgens Alleviate Allergic Airway Inflammation by Suppressing Cytokine Production in Th2 Cells.

Asthma is more common in females than males after adolescence. However, the mechanism of the sex bias in the prevalence of asthma remains unknown. To test whether sex steroid hormones have some roles in T cells during development of asthma, we analyzed airway inflammation in T cell-specific androgen receptor (AR)- and estrogen receptor (ER)-deficient mice. T cell-specific AR-deficient male mice developed severer house dust mite-induced allergic airway inflammation than did control male mice, whereas T cell-specific ERα- and ERß-deficient female mice exhibited a similar degree of inflammation as for control female mice. Furthermore, administration of dihydrotestosterone reduced cytokine production of Th2 cells from control, but not AR-deficient, naive T cells. Transfer of OT-II transgenic AR-deficient Th2 cells into wild-type mice induced severer allergic airway inflammation by OVA than transfer of control Th2 cells. Gene expression profiling suggested that the expression of genes related with cell cycle and Th2 differentiation was elevated in AR-deficient Th2 cells, whereas expression of dual specificity phosphatase (DUSP)-2, a negative regulator of p38, was downregulated. In addition, a chromatin immunoprecipitation assay suggested that AR bound to an AR motif in the 5' untranslated region of the Dusp2 gene in Th2 cells. Furthermore, the Dusp2 promoter with a wild-type AR motif, but not a mutated motif, was transactivated by dihydrotestosterone in a reporter assay. Finally, forced expression of DUSP-2 by retrovirus vector reduced IL-4 expression in Th2 cells. Thus, these results suggest that androgen signaling suppresses cytokine production of Th2 cells by inducing DUSP-2, explaining, in part, the sex bias of asthma after adolescence.

Alveolar Hemorrhage Caused by the Combination of Immune Checkpoint Inhibitors (ICIs) and Angiogenesis Inhibitors: The Underlying Long-Term Vascular Endothelial Growth Factor (VEGF) Inhibition.

The combination of immune checkpoint inhibitors (ICIs) and other anticancer agents is the standard of care for various cancers. Bevacizumab, an anti-angiogenesis inhibitor, causes serious adverse events such as pulmonary hemorrhage (PH). Here, we present a case of drug-induced diffuse alveolar hemorrhage (DAH), an adverse event, in a patient with hepatocellular carcinoma who was treated with a combination of ICIs and anti-angiogenesis inhibitors after long-term use of lenvatinib, which inhibits vascular endothelial growth factor (VEGF). An 85-year-old man with hepatocellular carcinoma initially received lenvatinib, a multi-kinase inhibitor, but the drug was later switched to bevacizumab-atezolizumab combination therapy owing to disease progression. After five cycles, he developed dyspnea and diffuse ground-glass opacities, which improved with discontinuation of the combination therapy and initiation of steroid pulse therapy. Our case findings indicate that both ICIs and anti-angiogenesis inhibitors cause drug-induced DAH, and their combination may increase the severity of DAH. Moreover, long-term VEGF inhibition may induce the development of DAH. Clinicians need to be aware that long-term VEGF inhibition may be associated with DAH and should consider the risk management of such adverse events while using this combination therapy.

Diagnostic value of endometrial cytology and related technology.

BACKGROUND: Endometrial cytology is not much popular in the world, but is commonly used in a few countries. Although cytomorphological evaluation of endometrial cytology is complicating, recent advance in technology helps improve diagnostic accuracy. In addition, new reporting system, The Yokohama System, has been introduced as a standard reporting system resembling The Bethesda System of the uterine cervical cytology. Although sample standardization is one of the causes in diagnostic problem, it was solved by liquid-based cytology (LBC) technology. In addition, standardized diagnostic algorithm by cytomorphological assessment of LBC samples, the Osaki Study Group (OSG) method, was recently proposed as a reliable and reproducible method. LBC can be utilized for ancillary methods. Application of immunocytochemistry and molecular technology on endometrial cytology samples has been studied to improve diagnostic accuracy. Recent progress of molecular technology has revealed many driver gene mutations in endometrial cancer and its precursors. Surprisingly, many studies revealed that even normal endometrial tissue had driver gene mutations. CONCLUSION: Based on the recent advance in knowledge of molecular profile of endometrial lesions and normal endometrial tissue, endometrial cytology will gain much power in clinical usefulness.

Application of immunocytochemical and molecular analysis of six genes in liquid-based endometrial cytology.

BACKGROUND: The Yokohama System of Endometrial Cytology has been used for reporting endometrial cytology, which includes gray zone category, atypical endometrial cells (ATEC), subdivided into ATEC-US and ATEC-AE. ATEC-US has been reported to be correlated with malignancy in nearly 10% of the cases. For accurate diagnosis, application of ancillary techniques on endometrial cytology was investigated. METHODS: Thirty-seven liquid based cytological specimens (SurePath™) with diagnosis of ATEC or malignant which have corresponding histological specimens, were subjected to immunocytochemical analysis for ß-catenin, ARID1A, and PTEN. Hot spots of mutations for KRAS, BRAF and PIK3CA were evaluated by using i-densy system (ARKRAY). RESULTS: In endometrial samples with the diagnosis of ATEC and malignant, aberrant gene expressions and/or gene mutations for ß-catenin, ARID1A, PTEN, KRAS, BRAF, and PIK3CA were observed in 32.4, 18.9, 37.8, 18.8, 0, and 37.1%, respectively. When any of the genes had aberrant expression or mutation, only sensitivity was better than that of cytology (77 vs. 53.8%). However, specificity, positive predictive value, negative predictive value, and accuracy was better in cytology than those of ancillary techniques. Increasing rate of abnormality according to the consequent histology results was observed in ARID1A (p = .015). Frequent loss of PTEN immunostaining (45.8%) and PIK3CA mutation (43.5%) was observed in the cases with consequent benign histology results. CONCLUSION: In ATEC category of endometrial cytology, gene expression and mutation analysis of six genes were insufficient to aid conventional cytological diagnoses albeit increased sensitivity. Further investigation would be necessary.

A Case of Endometrial Carcinosarcoma Containing Sertoliform Endometrioid Carcinoma Component.

Carcinosarcomas (CSs) of the endometrium have admixture of malignant epithelial and mesenchymal components. The carcinomatous component exhibit endometrioid, serous, or clear cell differentiation, or are undifferentiated. CSs are considered homologous or heterologous according to the type of sarcomatous component. Sertoliform endometrioid carcinomas (SECs) of the endometrium which comprise a rare subtype of endometrial cancer, typically occur in the ovary. SECs as a carcinomatous component of CS of the endometrium have not been reported. Here, we report an endometrial carcinosarcoma that contains an SEC component. An 88-year-old female presented to a clinic with atypical genital bleeding. She was referred to our hospital and underwent total hysterectomy, bilateral adnexectomy and partial omentectomy due to endometrial carcinoma. Gross examination revealed a polypoid mass in the uterine cavity with massive myometrial invasion. Histologically, the tumor was a high-grade endometrioid carcinoma. In addition to an ordinary conventional endometrioid carcinoma, approximately 30% of the area exhibited sex cord-like pattern and contained small hollow tubules, anastomosing cords and trabeculae, and tightly packed nests. Immunohistochemically, the SEC component showed diffuse p53 staining. Sex cord-like area, especially the solid area, showed positive staining for EMA, vimentin, α-inhibin, CD99, calretinin, p53, CD56, synaptophysin, and chromogranin A, which is a staining pattern similar to that previously reported SEC of the endometrium. Diminished membranous and positive cytoplasmic staining for ß-catenin was observed. This is the first case report of an endometrial carcinosarcoma containing an SEC component. SECs of the endometrium might exhibit sex cord-like differentiation in contrast to SECs of the ovary, which do not exhibit sex cord differentiation.

Enhanced immune reaction resulting from co-vaccination of WT1 helper peptide assessed on PET-CT.

It has become evident that positron emission tomography/computed tomography (PET-CT) using 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) (FDG PET-CT) can detect anti-tumor immune response induced by various immunotherapies. To evaluate whether FDG PET-CT could detect anti-cancer immune response caused by cancer vaccine therapy, we performed a retrospective analysis of FDG PET-CT imaging of patients who were treated with Wilms Tumor 1 (WT1) vaccine therapy in Osaka University during July 2008 and June 2018. Increased FDG uptakes were detected in WT1-vaccinated skin and their draining lymph nodes during the repeated vaccination. While the FDG uptakes seemed to decrease with time after the cessation of WT1 peptide vaccinations, persistence of FDG uptakes for years in WT1-vaccinated skin were also observed in 2 cases who showed good clinical course. Moreover, the FDG uptakes of patients treated with the combination vaccine of WT1 specific cytotoxic T cell (CTL) and helper peptides were significantly stronger than of those treated with the WT1 CTL peptide alone. Since it is evident that the combination vaccine can induce a more robust anti-tumor immunity than can CTL peptide vaccine alone, the FDG uptakes in WT1-vaccinated skin might reflect the degree of immune response. These results suggest that PET-CT might be a good tool for prediction of anti-tumor immune response induced by WT1 vaccine therapy. Larger scale prospective studies therefore seem to be warranted.

Detection of MEAF6-PHF1 translocation in an endometrial stromal nodule.

Endometrial stromal nodule (ESN) and low-grade endometrial stromal sarcoma (LG-ESS) are rare uterine tumors known as endometrial stromal tumors (ESTs). In addition to their similarity in morphological features, recent studies have shown that these two tumors share common genetic alterations. In particular, JAZF1-SUZ12 fusion is found with high frequency in both ESN and LG-ESS. In LG-ESS, some minor fusions have also been described, which include rearrangements involving PHF1 and its partner genes, such as JAZF1, EPC1, MEAF6, BRD8, EPC2, and MBTD1. Because of the rarity of ESN, genetic alterations other than JAZF1 fusion have not been investigated in detail. In this study, we performed a next-generation sequencing-based analysis in a case of ESN with peripheral metaplastic bone formation and detected MEAF6-PHF1 fusion, which has been reported in a small subset of uterine LG-ESSs and soft tissue ossifying fibromyxoid tumors. The finding that MEAF6-PHF1 fusion is a background genetic abnormality detected both in ESN and LG-ESS, along with JAZF1-SUZ12, provides further support for the similarity and continuum between these two types of ESTs. Furthermore, the association between metaplastic bone formation and MEAF6-PHF1 fusion may not be limited to soft tissue tumors.

Case Report of Atypical Juxtaglomerular Cell Tumor.

Juxtaglomerular cell tumor (JGCT) is a rare renal tumor, producing renin and behaving almost in a benign fashion. So far, only three cases have been reported as malignant. We report a rare case with atypical JGCT. A 74-year-old male was referred to our hospital due to hypertension, proteinuria, and hematuria. Abdominal CT revealed a mass measured in 9.7×7.0 cm in the lower portion of the right kidney. Right kidney was removed laparoscopically. Grossly, white to tan tumor with massive hemorrhage and necrosis occupied the lower portion of the right kidney. Microscopically, tumor grew in a solid fashion. Tumor cells were polygonal to ovoid cells with round nuclei and clear to eosinophilic cytoplasm. Mitosis was found in 5 per 10 HPF. Immunohistochemically, tumor cells were stained by vimentin and CD34. Some tumor cells were also positive for renin. Electron micrograph showed near rhomboid crystalline structure in the tumor cells. Because of massive necrosis and mitotic figures, diagnosis of atypical (potentially malignant) JGCT was rendered. Gene mutations for IDH1, PIK3CA, K-ras, N-ras, Braf, and EGFR were not found by MBP-QP system.

Oxidative stress responses in human bronchial epithelial cells exposed to cigarette smoke and vapor from tobacco- and nicotine-containing products.

The use of novel tobacco- and nicotine-containing vapor products that do not combust tobacco leaves is on the rise worldwide. The emissions of these products typically contain lower numbers and levels of potentially harmful chemicals compared with conventional cigarette smoke. These vapor products may therefore elicit fewer adverse biological effects. We compared the effects of emissions from different types of such products, i.e., our proprietary novel tobacco vapor product (NTV), a commercially available heat-not-burn tobacco product (HnB), and e-cigarette (E-CIG), and a combustible cigarette in a human bronchial epithelial cell line. The aqueous extract (AqE) of the test product was prepared by bubbling the produced aerosol into medium. Cells were exposed to the AqEs of test products, and then glutathione oxidation, Nrf2 activation, and secretion of IL-8 and GM-CSF were examined. We found that all endpoints were similarly perturbed by exposure to each AqE, but the effective dose ranges were different between cigarette smoke and the tobacco- and nicotine-containing vapors. These results demonstrate that the employed assays detect differences between product exposures, and thus may be useful to understand the relative potential biological effects of tobacco- and nicotine-containing products.

Invasive Micropapillary Carcinoma of the Uterine Cervix: Case Report of a Rare Entity.

Invasive micropapillary carcinoma (IMPC) is a rare subtype of adenocarcinoma found in many organs. Only 1 case of IMPC of the uterine cervix has been reported. We report a rare case of IMPC in the uterine cervix. A 61-yr-old woman presented to our hospital for vaginal bleeding and abdominal pain. A papillary tumor was found in the uterine cervix. Cervical cytology revealed abnormal cells suggesting carcinoma in situ and adenocarcinoma. A follow up biopsy revealed adenocarcinoma. She underwent radical hysterectomy and bilateral adnexectomy. Histologically, carcinoma in situ and IMPC were found in the uterine cervix. Lymphatic infiltration was present in the cerix and in the right cardinal ligament. A pelvic lymph node metastasis was also identified. Clinical FIGO stage was IIb and pathologic stage was pT2bN1M0. Postoperative positron emission tomography-computed tomography revealed paraaortic lymph node metastasis. She is alive with disease 2 yr 9 mo after surgery. Positive p16 immunostaining and high-risk human papilloma virus in situ hybridization revealed human papilloma virus infection. Interleukin-17 was expressed in the tumor cells which might be related to the extensive neutrophilic infiltration and tumor progression. This is the first case report in which interleukin-17 expression is observed in the tumor cells of IMPC.

[A Case of Epithelioid Angiomyolipoma of the Kidney with Tumor Thrombus Extending into the Renal Vein : Case Report].

A 31-year-old man was referred to our hospital for macroscopic hematuria. An abdominal computed tomography (CT) scan showed a 36×30 mm enhancing left renal tumor with tumor thrombus extending into the left renal vein. Therefore,we diagnosed the tumor as a clinically classified cT3aN0M0 left renal cell carcinoma. Retroperitoneal laparoscopic radical left nephrectomy with renal vein thrombectomy was performed,with removal of the left kidney with the mass and tumor thrombus en bloc. The pathological diagnosis was epithelioid angiomyolipoma (EAML) of the left kidney. EAML is a rare tumor with malignant potential. In this case,although no signs of recurrence or metastasis have been observed for 9 months post-operation,we recommended a careful follow-up regimen.

Hyperphosphatasemia in leiomyosarcoma of the uterus: Two case reports and a literature review.

Some tumors are known to produce alkaline phosphatase (ALP). Seven cases of uterine leiomyosarcoma were identified from the clinical records of Sakai City Medical Center from January 2006 to December 2014. Patients' ages ranged from 47 to 75 years (median: 58). Clinical stages were IB, IIB, IIIA, and IVB in four, one, one, and one cases, respectively. Of these, two were found to have hyperphosphatasemia before surgery, and the elevated ALP level decreased after surgery, and increased with disease recurrence. In the cases of hyperphosphatasemia, leiomyosarcoma cells showed positive staining for ALP. There was no correlation between serum ALP and lactate dehydrogenase, or ALP and cancer antigen 125. The combination of ALP, lactate dehydrogenase, and cancer antigen 125 may be more useful for diagnosis and follow-up of leiomyosarcoma.

Malignant Transformation of Mature Cystic Teratoma Diagnosed after a 10-Year Interval.

A 67-year-old uniparous woman had undergone surgery for acute perforated gastric ulcer 10 years prior to the current presentation. Although abdominal computed tomography (CT) performed at that point had revealed a mature cystic teratoma measuring 6 cm in diameter in the right ovary, it was left untreated. She visited the department of surgery at our hospital with chief complaints of appetite loss, nausea, and vomiting that had persisted for the prior two weeks. She was admitted with a diagnosis of ileus attributed to an abdominal incisional hernia. CT performed on admission revealed a tumor measuring 21 cm in diameter with mural nodules in the right ovary. Thus, surgery was performed under suspicion of malignant transformation of the previously detected ovarian mature cystic teratoma. While neither lymphadenopathy nor distant metastasis was detected by imaging studies, bilateral adnexectomy and repair of the abdominal incisional hernia were performed. Cytology of ascites was negative. The postoperative pathological diagnosis was squamous cell carcinoma arising from teratoma, and the postoperative clinical diagnosis was stage IA ovarian cancer. It was assumed that the mature cystic teratoma which had been detected in the right ovary 10 years earlier had undergone malignant transformation.

Primary Marginal Zone Lymphoma in the Posterior Mediastinum with Pleural Involvement.

We herein report a case of primary marginal zone lymphoma (MZL) of the posterior mediastinum in an 84-year-old woman. Computed tomography of the chest showed a posterior mediastinal mass in the right thoracic paravertebral region with right pleural effusion. Pathological findings of a surgical biopsy from the posterior mediastinum, along with immunohistochemical and flow cytometric results, indicated MZL. The patient was treated with chemotherapy and radiation therapy for the mediastinal lesion and achieved complete remission. A relapse occurred 3 months after the initial treatment regimen. However, a second relapse has not occurred more than 2 years after second-line chemotherapy. This is the first case of MZL originating in the posterior mediastinum.