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(Objective)Retroperitoneal fibrosis is largely divided into the idiopathic and secondary types. Some idiopathic cases include IgG4-related diseases, which are often similar to malignant diseases, such as lymphoma and sarcoma. The diagnostic criteria for IgG4-related disease are used and pathologic examination is necessary for a definitive diagnosis of IgG4-related retroperitoneal fibrosis. The first choice of treatment for IgG4-related retroperitoneal fibrosis is steroid administration, but no consensus has been established regarding its dose and tapering schedule. We investigated the significance of IgG4 in diagnosis and treatment of idiopathic retroperitoneal fibrosis. (Patients and methods)We examined 14 cases diagnosed as idiopathic retroperitoneal fibrosis between April 2013 and March 2019. Serum IgG4 was measured at the time of diagnosis in 13 cases, and changes over time in serum IgG4 before and after the induction of steroid therapy were measured in 6 cases. Computed tomography-guided biopsy was performed on 4 cases. (Results)Of all cases, 1 patient was diagnosed as IgG4-related retroperitoneal fibrosis and 5 patients were classified as possible group. Ten patients were administered steroid therapy. Percutaneous nephrostomy tube was placed in 3 patients and was removed in 2 of these patients after steroid therapy. The serum high levels of IgG4 were confirmed in all 4 patients who were classified into the possible group and who were treated with steroids. (Conclusion)Although histologic examination is necessary for the diagnosis of retroperitoneal fibrosis, tissue collection by open or laparoscopic surgery is highly invasive. CT-guided biopsy may be useful in high-risk cases, such as elderly patients on anticoagulation. After excluding other diseases in high-risk cases, response to empiric steroid therapy may be diagnostic. In the possible group, changes in serum IgG4 levels may reflect the disease condition and might be useful in determining the maintenance dose of steroids.

Epithelioid malignant peripheral nerve sheath tumor (MPNST) is a rare subtype of MPNST composed of epithelioid cells with abundant cytoplasm. Currently, strong and diffuse immunostaining for S100 protein and SOX10 is generally regarded as a characteristic feature of epithelioid MPNST. However, malignant tumors with epithelioid morphology that arise from a peripheral nerve or a pre-existing benign nerve sheath tumor should be regarded as epithelioid MPNSTs when they do not show characteristic features that definitively lead to other specific diagnoses. Here, we describe 3 cases of epithelioid MPNST in the peripheral nerve or schwannoma that was negative for S100 protein and SOX10 expression. Instead, these tumors were positive for EMA, GLUT1, claudin 1, and cytokeratin to varying degrees, while all of them retained SMARCB1 and H3K27me3 by immunohistochemistry. EMA, GLUT1, and claudin 1 are known markers of perineurial cell differentiation; thus, they could possibly represent epithelioid MPNST with perineurial cell differentiation.

Background Presepsin is a diagnostic and prognostic biomarker of both bacterial infection and sepsis; however, elevated presepsin levels have also been observed without sepsis. We conducted several analyses to evaluate the clinical laboratory parameters affecting presepsin levels. Method We analyzed the association between sequential organ failure assessment (SOFA) scores and plasma presepsin levels and then analyzed clinical laboratory parameters in 567 patients with univariate and multivariate regression analysis and analysis of covariance (ANCOVA). We also determined presepsin in the bile of 11 patients and examined the presepsin immunostaining in liver. Results Spearman’s rank correlation analysis with loge change revealed that presepsin levels were closely associated with loge-transformed SOFA score (ρ = 0.541), alkaline phosphatase (ALP); (ρ = 0.454) and gamma-glutamyl transferase; (ρ = 0.505). Multivariate regression analysis revealed that loge-transformed SOFA score (β-coefficient = 0.316), ALP level (β-coefficient = 0.380), and creatinine level (β-coefficient = 0.290) independently and significantly affected loge presepsin levels. ANCOVA revealed that presepsin levels were significantly higher in patients with hepatobiliary disease. Patients who presented with dilatation of the bile ducts and elevated ALP levels or total bilirubin levels exhibited high presepsin levels in the bile. Presepsin production in liver Kupffer cells was also confirmed by immunostaining. Conclusion Presepsin levels is correlated with the elevation of biliary enzymes in patients without renal dysfunction or sepsis. Additionally, presepsin exists with high concentrations in the bile and is positive in Kupffer cells.

We treated a man with co-incident Marfan-like connective tissue disease with morphologic left ventricular non-compaction (LVNC). He underwent valve-sparing aortic root replacement because of aortic root dilation at 43 years old. Pathological findings of the aorta revealed cystic medio-necrosis, consistent with Marfan syndrome. He developed congestive heart failure caused by LVNC at 47 years old. His daughter had scoliosis, and he had several physical characteristics suggestive of Marfan syndrome. We herein report a rare case of a patient who had Marfan-like connective disease with an LVNC appearance.

BACKGROUND: The assessment of lymphovascular invasion (LVI) on the specimens of a transurethral resection of bladder tumors (TURBT) is very important for risk stratification and decision-making on further treatment for bladder cancer. OBJECTIVES: The present study aimed to identify clinical predictors associated with the risk of bladder cancer with LVI before a first TURBT. METHODS: A total of 291 patients underwent a first TURBT for bladder cancer at Toho University Sakura Medical Center between January 2012 and December 2016. We analyzed predictors of LVI based on data from 217 patients and predictors of high grade and ≥ pT1 tumors based on data from the medical records of 237 patients for comparison with LVI risk factors. RESULTS: Univariate analysis significantly associated LVI with episodes of gross hematuria, positive urinary cytology, and larger, non-papillary and sessile tumors. Multivariate analysis selected larger tumors [odds ratio (OR) 1.39; 95 % confidence interval (CI) 1.08-1.78; p = 0.01], and non-papillary (OR 10.05; 95% CI 3.75-26.91; p < 0.01) and sessile (OR 2.65; 95% CI 1.18-5.93; p = 0.02) tumors as significant predictors of LVI. Some predictors such as tumor size and non-papillary tumors overlapped between high-grade and ≥ pT1 bladder cancer. CONCLUSIONS: These predictors can help clinicians to identify patients with, or who are at high-risk for LVI before undergoing a first TURBT and to determine priorities for preoperative evaluation and scheduling consecutive treatments.

Background Cytokeratin-positive interstitial reticulum cells (CIRCs), which are a subgroup of fibroblastic reticular cells (FRCs), are known to be present in the lymph nodes. There have been only a few cases of tumors derived from CIRCs. Case presentation We have reported a new case involving a CIRC tumor in a 75-year-old man and reviewed the literature. The resected mediastinal lymph nodes showed epithelial-like proliferation of large atypical round and polygonal epithelioid cells. The tumor cells expressed CK8, CK18, CAM5.2, AE1/AE3, epithelial membrane antigen, vimentin, fascin, and some FRC markers, which is consistent with the diagnosis of a CIRC tumor. Following chemotherapy, the CIRC tumor was observed to have responded very well and became difficult to confirm on imaging, but a small cell lung carcinoma developed 12 months later. Chemoradiotherapy was performed, but the patient passed away 29 months after the initial diagnosis. The autopsy revealed the recurrence of the CIRC tumor, residual small cell lung carcinoma, and a very small latent carcinoma of the prostate. The relapsed CIRC tumor cells had a spindle shape; they were highly pleomorphic and had invaded the superior vena cava. Conclusion We first reported autopsy findings of CIRC tumors and demonstrated the transformation of the tumor from the epithelioid cell type to the spindle cell type.

Neurofibromatosis type 1 (NF1) is one of the most common genetic neurocutaneous disorders, and it is well known to be associated with peripheral or central nervous system malignancies. The most common malignant tumors are malignant peripheral nerve sheath tumors (MPNSTs); MPNSTs are the most common cause of death in patients with NF1. Central nervous system malignancies rarely occur. So far, the occurrence of spinal cord malignancies is exceedingly rare. Herein, we report a rare case of a 69-year-old male with NF1 following tumor resection twice for cutaneous MPNSTs developing intramedullary diffuse astrocytoma in the conus medullaris, which initially presented with traumatic spinal cord injury associated with a compression fracture from fall. Contrast-enhanced magnetic resonance imaging and biopsy of the spinal cord were required to establish the final diagnosis.

To elucidate tumor cell behavior associated with cancer stem cell (CSC) marker expression, the expression of CD133, CD44v9, and ALDH1A1, which are considered markers of CSCs, was examined in sporadic and ulcerative colitis (UC)-associated colorectal tumors.A total of 23 cases of sporadic colorectal cancer and 44 cases of adenoma were collected. Additionally, 22 cancer lesions and 38 dysplasia lesions were selected from 28 colectomy cases of UC with neoplastic lesions. Lesions were examined by immunohistochemistry using primary antibodies against CD133, CD44v9, ALDH1A1, Ki-67, cleaved-Caspase 3, and p53.CD133, CD44v9, and ALDH1A1 showed higher expression in both sporadic and UC-associated tumors than in the normal mucosa. ALDH1A1 expression in sporadic cancer was higher in the right colon than in the left colon (p=0.0089). ALDH1A1 expression in UC-associated cancer was higher in those with longer disease duration than in those with shorter disease duration (p=0.019). The CD44v9+/CD133- region had fewer cleaved-Caspase 3 positive cells in both sporadic and UC-associated cancers. In sporadic cancer, CD133+/ALDH1A1+ regions had fewer apoptotic cells than CD133+/ALDH1A1- regions, while CD133+/ALDH1A1- regions were less proliferative than CD133+/ALDH1A1+ regions in UC-associated cancer.CD44+/CD133- regions were commonly associated with low apoptosis in sporadic and UC-associated cancers; thus, these were considered target areas for CSCs. Additionally, the combination of markers comprising CSCs may differ between sporadic and UC-associated cancers.

Background Pre-eclampsia is a pregnancy-specific disease characterized by onset of hypertension and proteinuria, sometimes progressing into damaging other organs. Here, we investigated the pathological significance of the soluble fragment of LR11 (sLR11), a cell differentiation regulator, in comparison to circulating IL-6 and TNF-α, in pre-eclampsia. Methods The study was conducted in a cross-sectional research design with fourteen pre-eclampsia patients and fifty healthy pregnant subjects. Pre-eclampsia was defined as hypertensive disorders in pregnancy at over 20 weeks of gestation with proteinuria. Results Plasma levels of sLR11 as well as IL-6 in pre-eclampsia were increased compared with those in the healthy pregnant subjects at the first, the second, and the third trimester. Receiver operating characteristic analysis for the detection of pre-eclampsia among third-trimester subjects showed that the areas under the curves of sLR11 and IL-6 were equivalent. sLR11 and IL-6 correlated positively with TNF-α in healthy pregnant subjects. In the pre-eclampsia patients, there was neither a correlation between sLR11 and IL-6 nor between sLR11 and TNF-α. Conclusions sLR11 increases during pregnancy, with levels further exaggerated in pre-eclampsia, and may be related to the pathology of pre-eclampsia.

Triple-negative breast cancer (TNBC) is associated with poor prognosis, because of no effective targeted therapy. In the present study, we demonstrated the crucial role of the aryl hydrocarbon receptor (AhR) in mediating the effects of the chemotherapeutic agent doxorubicin (DOX) in the chemotherapeutic sensitivity of TNBC. Firstly, we established AhR knockout (KO) MDA-MB 231 TNBC cells. The cytotoxic effects of DOX were more pronounced in AhR KO cells than in parental cells. In addition, our results indicated that AhR KO cells showed downregulated expression of DOX-metabolism enzyme, aldo-keto reductase (AKR) 1C3, relative to those of parental cells. Furthermore, AhR was found to enhance AKR1C3 promoter reporter activity, suggesting that AKR1C3 mRNA transcription is activated by AhR. Additionally, our findings confirmed that the downregulation of AKR1C3 expression enhanced DOX sensitivity in MDA-MB 231 cells. Finally, AhR and AKR1C3 expression were positively correlated in human breast cancer. Taken together, our results suggested that AhR is involved in DOX sensitivity by regulating AKR1C3 expression in TNBC cells.

Background The levels of plasma sLR11, released from intimal SMCs, are positively associated with intima-media thickness (IMT) in asymptomatic subjects. We have evaluated the yet unknown pathological significance of sLR11 for plaque conditions in patients with carotid artery stenosis. Methods The presence of LR11 in carotid plaques was investigated using autopsy specimens. A clinical ultrasonography study for elucidating relationships between sLR11 and plaque condition was performed in 46 patients. Results Immunohistochemistry showed high levels of LR11 in SMCs within thickened intima and at the media-intima border of atherosclerotic carotid plaques. The levels of sLR11 in patients were clearly elevated compared to healthy controls. Univariate analysis of sLR11 revealed significant positive correlation with plaque score and a tendency to correlate with the stenotic fraction. Univariate and multiple regression analyses of plaque scores showed that sLR11, maximum IMT, and HDL-cholesterol independently determined plaque score. Finally, univariate analysis of initial sLR11 levels for changes in imaging markers after one-year follow-up showed that initial sLR11 levels significantly correlated with stenotic fraction progression. Conclusions The levels of sLR11, abundantly expressed in carotid atherosclerotic plaques, are highly associated with increased plaque score. sLR11 levels may be predictive of plaque conditions in patients with advanced carotid atherosclerosis.

Epithelioid malignant peripheral nerve sheath tumor (MPNST) is a rare subtype of MPNST composed of epithelioid cells with abundant cytoplasm. Currently, strong and diffuse immunostaining for S100 protein and SOX10 is generally regarded as a characteristic feature of epithelioid MPNST. However, malignant tumors with epithelioid morphology that arise from a peripheral nerve or a pre-existing benign nerve sheath tumor should be regarded as epithelioid MPNSTs when they do not show characteristic features that definitively lead to other specific diagnoses. Here, we describe 3 cases of epithelioid MPNST in the peripheral nerve or schwannoma that was negative for S100 protein and SOX10 expression. Instead, these tumors were positive for EMA, GLUT1, claudin 1, and cytokeratin to varying degrees, while all of them retained SMARCB1 and H3K27me3 by immunohistochemistry. EMA, GLUT1, and claudin 1 are known markers of perineurial cell differentiation; thus, they could possibly represent epithelioid MPNST with perineurial cell differentiation.

PurposePreoperative chemotherapy is widely applied to high-grade localized soft tissue sarcomas (STSs); however, the prognostic significance of histological response to chemotherapy remains controversial. This study aimed to standardize evaluation method of histological response to chemotherapy with high agreement score among pathologists, and to establish a cut-off value closely related to prognosis. MethodsUsing data and specimens from the patients who had registered in the Japan Clinical Oncology Group study, JCOG0304, a phase II trial evaluating the efficacy of perioperative chemotherapy with doxorubicin (DOX) and ifosfamide (IFO), we evaluated histological response to preoperative chemotherapy at the central review board.ResultsA total of 64 patients were eligible for this study. The percentage of viable tumor area ranged from 0.1% to 97.0%, with median value of 35.7%. Regarding concordance proportion between pathologists, the weighted kappa coefficient (κ) score in all patients was 0.71, indicating that the established evaluation method achieved substantial agreement score. When the cut-off value of the percentage of the residual tumor area was set as 25%, the p-value for the difference in overall survival showed the minimum value. Hazard ratio of the non-responder with percentage of the residual tumor < 25%, to the responder was 4.029 (95% confidence interval 0.893–18.188, p = 0.070). ConclusionThe standardized evaluation method of pathological response to preoperative chemotherapy showed a substantial agreement in the weighted κ score. The evaluation method established here was useful for estimating of the prognosis in STS patients who were administered perioperative chemotherapy with DOX and IFO.Trial registration UMIN Clinical Trials Registry C000000096. Registered 30 August, 2005 (retrospectively registered).

(1) Background: This study aimed to evaluate the associations of lymphovascular invasion (LVI) at first transurethral resection of bladder (TURBT) and radical cystectomy (RC) with survival outcomes, and to evaluate the concordance between LVI at first TURBT and RC. (2) Methods: We analyzed 216 patients who underwent first TURBT and 64 patients who underwent RC at Toho University Sakura Medical Center. (3) Results: LVI was identified in 22.7% of patients who underwent first TURBT, and in 32.8% of patients who underwent RC. Univariate analysis identified ≥cT3, metastasis and LVI at first TURBT as factors significantly associated with overall survival (OS) and cancer-specific survival (CSS). Multivariate analysis identified metastasis (hazard ratio (HR) 6.560, p = 0.009) and LVI at first TURBT (HR 9.205, p = 0.003) as significant predictors of CSS. On the other hand, in patients who underwent RC, ≥pT3, presence of G3 and LVI was significantly associated with OS and CSS in univariate analysis. Multivariate analysis identified inclusion of G3 as a significant predictor of OS and CSS. The concordance rate between LVI at first TURBT and RC was 48.0%. Patients with positive results for LVI at first TURBT and RC displayed poorer prognosis than other patients (p &lt, 0.05). (4) Conclusions: We found that the combination of LVI at first TURBT and RC was likely to provide a more significant prognostic factor.

Background: This study aimed to evaluate the associations of lymphovascular invasion (LVI) at first transurethral resection of bladder (TURBT) and radical cystectomy (RC) with survival outcomes, and to evaluate the concordance between LVI at first TURBT and RC. Methods: We reviewed 216 patients who underwent first TURBT and 64 patients who underwent RC at our hospital. Medical records were reviewed uniformly, collecting the following data: age, sex, clinical and pathological T stage, neoadjuvant chemotherapy, grade, metastasis, urinary cytology, carcinoma in situ and LVI. Results: LVI was identified in 22.7% of patients who underwent first TURBT, and 32.8% of patients who underwent RC. Univariate analysis identified ≥cT3, metastasis and LVI at first TURBT as factors significantly associated with overall survival (OS) and cancer-specific survival (CSS). Multivariate analysis identified metastasis (hazard ratio (HR) 6.560, p=0.009) and LVI at first TURBT (HR 9.205, p=0.003) as significant predictors of CSS. On the other hand, in patients who underwent RC, ≥pT3, inclusion of G3 and LVI were significantly associated with OS and CSS in univariate analysis. Multivariate analysis identified inclusion of G3 as a significant predictor of OS and CSS. The concordance rate between LVI at first TURBT and RC was 48.0%. Patients with positive results for LVI at first TURBT and RC displayed poorer prognosis than other patients (p

Presepsin is a diagnostic and prognostic biomarker of sepsis; however, elevated presepsin levels have also been documented without sepsis. This study aims to retrospectively analyze the laboratory parameters and Sequential Organ Failure Assessment (SOFA) score affecting presepsin levels in 567 patients. Some patients with elevated presepsin levels exhibited renal dysfunction or elevation of biliary enzymes despite a low SOFA score. The univariate regression analysis revealed a close correlation between presepsin levels and SOFA score, serum creatinine (CRE), blood urea nitrogen, and biliary enzymes. In addition, a multivariate regression analysis revealed that SOFA score, alkaline phosphatase (ALP), and CRE independently affected presepsin levels significantly. The analysis of covariance (ANCOVA) revealed that presepsin levels were significantly higher in patients with hepatobiliary disease. Besides, we found that patients who presented with the dilatation of intra- or extrahepatic bile ducts and the elevation of ALP or total bilirubin exhibited remarkable high presepsin levels in the bile. Furthermore, the presepsin production in the liver’s Kupffer cells was established by immunostaining in patients who received surgical liver resection. Overall, this study elucidates that biliary enzymes’ elevation affects presepsin levels, presepsin exists in high concentrations in the bile, and is positive in Kupffer cells.

Introduction Apparent diffusion coefficient (ADC) values on multiparametric magnetic resonance imaging (mpMRI) have been reported to correlate with high-Gleason score (GS) prostate cancer. However, the relative ADC values between tumor lesions and normal tissue have been suggested as more suitable than the absolute ADC values for evaluation of diffusion abnormalities, because absolute ADC values are susceptible to differences in scanners or scanner settings. The present study evaluated the usefulness of the relative assessment of ADC values between tumor lesions and normal tissue on preoperative mpMRI for the prediction of high-risk prostate cancer on radical prostatectomy specimens. Materials and methods A retrospective analysis of 48 men who underwent radical prostatectomy between January 2013 and December 2014 was conducted. MpMRI was performed with a 3.0-T scanner using b-values of 0 and 1500 s/mm2. ADC values of the tumor (ADCTUMOR) and normal prostate and the relative ADC tumor/normal ratio (ADCTNR) were evaluated by two radiologists. Results The inter-rater reliability between two radiologists for ADCTUMOR measurement was high, with Pearson's r = 0.982. There was no difference in ADCTUMOR between GS ≤7 and GS ≥8. In contrast, ADCTNR was significantly lower in GS ≥8 than in GS ≤7. ROC curves of ADCTNR to predict higher GS (≥8) showed better classification performance (AUC = 0.8243, p = .0012 by radiologist A and AUC = 0.7961, p = .0031 by radiologist B) than of ADCTUMOR. Conclusions The relative assessment of ADC values between tumor lesions and normal tissue could improve the detection rate of high-risk prostate cancers.

The upregulation of brown or brown-like beige adipocytes is a potential strategy for the prevention or treatment of diabetes and coronary artery diseases in obese patients. Epicardial adipose tissue (EAT) differs significantly from subcutaneous fat tissue (SAT) in metabolic properties. To investigate properties of EAT further, thermogenesis gene expression was investigated in human autopsy and murine samples, and adipocytes differentiated from EAT mesenchymal cells. Subsequently, analyzed EAT volume alterations were observed to be associated with weight reduction in obese patients by imaging. Gene expression analyses of autopsy samples revealed that UCP‑1 mRNA levels in EAT were significantly increased compared with SAT, and β3‑adrenergic receptor (AR) levels tended to be increased; this finding was verified in comparing EAT with SAT in mice. Browning stimulation of human EAT‑derived MCs increased uncoupling protein‑1 and β3‑AR levels by 3.2 fold‑ and 12.6‑fold compared with SAT‑derived MCs, respectively. Subsequent imaging for EAT volume measurement using multi‑detector computed tomography in 10 obese patients revealed that mean EAT volumes did not significantly decrease following weight loss therapy. The EAT volume alterations were not correlated with weight changes, whereas positive correlations were observed in SAT and visceral adipose tissue. Therefore, the studies in man and mouse on EAT properties demonstrated that susceptibilities of EAT and SAT for browning‑gene expression and diet‑induced volume reduction were grossly different. The data suggest a potential association of EAT with local thermogenetic and metabolic homeostasis in cardiac and/or cardiovascular cells, in conjunction with systemic energy metabolism.

Coronary calcification is a risk factor for ischemic heart disease. Hydroxyapatite that is formed by polymerization from calcium phosphate tribasic (CPT) is the major constituent of coronary calcium deposits. If CPT could be visualized, coronary calcification could be predicted and prevented. We discovered that when CPT and collagen I, the main constituent of collagen fibers, are mixed with lac dye (LD) and then exposed to fluorescent light excited at 345 ± 15 nm and emitted at 420 nm, a purple fluorescence that is characteristic of CPT only is elicited. So, we examined localization of CPT and its relation to plaque morphology by color fluorescent angioscopy (CFA) or microscopy (CFM) in 24 coronary arteries obtained from 12 autopsy subjects. By CFA, the incidence (%) of CPT as confirmed by purple fluorescence in 15 normal segments, 25 white plaques, 14 yellow plaques without necrotic core (NC) and 8 yellow plaques with NC was 20, 36, 64 and 100 (p

Deep learning using deep convolutional neural networks (DCNNs) has demonstrated unprecedented power in image classification. Subsequently, computer-aided diagnosis (CAD) for pathology imaging has been largely facilitated by DCNN approaches. However, because DCNNs require massive amounts of labeled data, the lack of availability of such pathology image data as well as the high cost of labeling new data is currently a major problem. To avoid expensive data labeling efforts, transfer learning is a concept intended to overcome training data shortages by passing knowledge from the source domain to the target domain. However, weak relevance between the source and target domains generally leads to less effective transfers. Therefore, following the natural step-by-step process by which humans learn and make inferences, a stepwise fine-tuning scheme is proposed by introducing intermediate domains to bridge the source and target domains. The DCNNs are expected to acquire general object classification knowledge from a source domain dataset such as ImageNet and pathology-related knowledge from intermediate domain data, which serve as fundamental and specific knowledge, respectively, for the final benign/malignant classification task. To realize this, we introduce several ways to provide pathology-related knowledge by generating an intermediate dataset classified into various corresponding pathology features. In experiments, the proposed scheme has demonstrated good performance on several well-known deep neural networks.

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) may develop in association with several malignancies. However, as an immunohistochemical analysis is not performed in the majority cases, its true cause is often uncertain. We herein report a case of SIADH following chemotherapy due to tumor-derived ADH production in a patient with mucosa-associated lymphoid tissue (MALT) lymphoma. A retrospective immunohistochemical analysis demonstrated ADH expression by lymphoma cells. These findings highlight the importance of using an immunohistochemical analysis to determine ADH production by tumor cells in patients with SIADH. Such analyses play an important role in elucidating the pathogenesis of SIADH and determining the most appropriate treatment.