Clinical Role of Upfront F-18 FDG PET/CT in Determining Biopsy Sites for Lung Cancer Diagnosis.

PURPOSE: This study aimed to investigate the impact of FDG PET/CT timing for biopsy site selection in patients with stage IV lung cancer regarding complications and diagnostic yield. METHODS: This retrospective analysis was performed on 1297 patients (924 men and 373 women with a mean age of 71.4 ± 10.2 years) who underwent percutaneous needle biopsy (PNB) for stage IV lung cancer diagnosis in two hospitals. Data collected included the patient's characteristics, order date of the biopsy and PET/CT exams, biopsy target site (lung or non-lung), guidance modality, complications, sample adequacy, and diagnostic success. Based on the order date of the PNB and PET/CT exams, patients were categorized into upfront and delayed PET/CT groups. RESULTS: PNB for non-lung targets resulted in significantly lower rates of minor (8.1% vs. 16.2%), major (0.2% vs. 3.4%), and overall complications (8.3% vs. 19.6%) compared to PNB for lung targets (p < 0.001 for all types of complications). Compared to the delayed PET/CT group, the upfront PET/CT group exhibited a lower probability of lung target selection of PNB (53.9% vs. 67.1%, p < 0.001), including a reduced incidence of major complications (1.0% vs. 2.9%, p = 0.031). Moreover, there was no significant difference in the occurrence of minor and total complications between the two groups. Upfront PET/CT and delayed PET/CT groups showed no significant difference regarding sample adequacy and diagnostic success. CONCLUSIONS: Upfront PET/CT may have an impact on the selection of the biopsy site for patients with advanced lung cancer, which could result in a lower rate of major complications with no change in the diagnostic yield. Upfront PET/CT demonstrates potential clinical implications for enhancing the safety of lung cancer diagnosis in clinical practice.

Immunoglobulin G4-Related Lung Disease with Waxing and Waning Pulmonary Infiltrates: A Case Report.

Immunoglobulin G4 (IgG4)-related lung disease can have various clinical courses. To our knowledge, reports of IgG4-related lung disease with waxing and waning pulmonary infiltrates only are very rare. A few lung nodules and ground glass opacities were incidentally found in a pre-operative evaluation in a 36-year-old female. The lung lesions showed waxing and waning in the follow-up chest CT. She underwent a surgical biopsy, and IgG4-related lung disease was confirmed.

Genetic landscape and PD-L1 expression in Epstein-Barr virus-associated gastric cancer according to the histological pattern.

Epstein-Barr virus (EBV)-associated gastric cancer (EBVaGC) is a distinct molecular subtype of gastric cancer. This study aims to investigate genomic and clinicopathological characteristics of EBVaGC according to the histological pattern. We retrospectively collected 18 specimens of surgically resected EBVaGCs. Whole-exome sequencing was performed for all cases. Moreover, PD-L1 expression and tumor-infiltrating lymphocyte (TIL) percentage were investigated. Among 18 EBVaGCs, 10 cases were of intestinal histology, 3 were of poorly cohesive histology, and the remaining 5 were of gastric carcinoma with lymphoid stroma histology. Whole-exome sequencing revealed that EBVaGCs with intestinal histology harbored pathogenic mutations known to frequently occur in tubular or papillary adenocarcinoma, including TP53, KRAS, FBXW7, MUC6, ERBB2, CTNNB1, and ERBB2 amplifications. One patient with poorly cohesive carcinoma histology harbored a CDH1 mutation. Patients with EBVaGCs with intestinal or poorly cohesive carcinoma histology frequently harbored driver mutations other than PIK3CA, whereas those with EBVaGCs with gastric carcinoma with lymphoid stroma histology lacked other driver mutations. Moreover, the histological pattern of EBVaGCs was significantly associated with the levels of TILs (P = 0.005) and combined positive score (P = 0.027). In conclusion, patients with EBVaGCs with different histological patterns exhibited distinct genetic alteration, PD-L1 expression, and degree of TILs.

Preoperative sequential short-course radiation therapy and FOLFOX chemotherapy versus long-course chemoradiotherapy for locally advanced rectal cancer: a multicenter, randomized controlled trial (SOLAR trial).

BACKGROUND: Preoperative (chemo)radiotherapy has been widely used as an effective treatment for locally advanced rectal cancer (LARC), leading to a significant reduction in pelvic recurrence rates. Because early administration of intensive chemotherapy for LARC has more advantages than adjuvant chemotherapy, total neoadjuvant therapy (TNT) has been introduced and evaluated to determine whether it can improve tumor response or treatment outcomes. This study aims to investigate whether short-course radiotherapy (SCRT) followed by intensive chemotherapy improves oncologic outcomes compared with traditional preoperative long-course chemoradiotherapy (CRT). METHODS: A multicenter randomized phase II trial involving 364 patients with LARC (cT3-4, cN+, or presence of extramural vascular invasion) will be conducted. Patients will be randomly assigned to the experimental or control arm at a ratio of 1:1. Participants in the experimental arm will receive SCRT (25 Gy in 5 fractions, daily) followed by four cycles of FOLFOX (oxaliplatin, 5-fluorouracil, and folinic acid) as a neoadjuvant treatment, and those in the control arm will receive conventional radiotherapy (45-50.4 Gy in 25-28 fractions, 5 times a week) concurrently with capecitabine or 5-fluorouracil. As a mandatory surgical procedure, total mesorectal excision will be performed 2-5 weeks from the last cycle of chemotherapy in the experimental arm and 6-8 weeks after the last day of radiotherapy in the control arm. The primary endpoint is 3-year disease-free survival, and the secondary endpoints are tumor response, overall survival, toxicities, quality of life, and cost-effectiveness. DISCUSSION: This is the first Korean randomized controlled study comparing SCRT-based TNT with traditional preoperative LC-CRT for LARC. The involvement of experienced colorectal surgeons ensures high-quality surgical resection. SCRT followed by FOLFOX chemotherapy is expected to improve disease-free survival compared with CRT, with potential advantages in tumor response, quality of life, and cost-effectiveness. TRIAL REGISTRATION: This trial is registered at Clinical Research Information under the identifier Service KCT0004874 on April 02, 2020, and at Clinicaltrial.gov under the identifier NCT05673772 on January 06, 2023.

Response Prediction after Neoadjuvant Chemotherapy for Colon Cancer Using CT Tumor Regression Grade: A Preliminary Study.

Purpose: To investigate whether CT-based tumor regression grade (ctTRG) can be used to predict the response to neoadjuvant chemotherapy (NAC) in colon cancer. Materials and Methods: A total of 53 patients were enrolled. Two radiologists independently assessed the ctTRG using the length, thickness, layer pattern, and luminal and extraluminal appearance of the tumor. Changes in tumor volume were also analyzed using the 3D Slicer software. We evaluated the association between pathologic TRG (pTRG) and ctTRG. Patients with Rödel's TRG of 2, 3, or 4 were classified as responders. In terms of predicting responder and pathologic complete remission (pCR), receiver operating characteristic was compared between ctTRG and tumor volume change. Results: There was a moderate correlation between ctTRG and pTRG (ρ = -0.540, p < 0.001), and the interobserver agreement was substantial (weighted κ = 0.672). In the prediction of responder, there was no significant difference between ctTRG and volumetry (Az = 0.749, criterion: ctTRG ≤ 3 for ctTRG, Az = 0.794, criterion: ≤ -27.1% for volume, p = 0.53). Moreover, there was no significant difference between the two methods in predicting pCR (p = 0.447). Conclusion: ctTRG might predict the response to NAC in colon cancer. The diagnostic performance of ctTRG was comparable to that of CT volumetry.

Comparison of immunohistochemistry and next-generation sequencing results in oncogenic PTEN missense mutations.

BACKGROUND: Phosphatase and tensin homolog (PTEN) is one of the most frequently mutated tumor suppressor genes in malignant tumors. Oncogenic PTEN mutations have diagnostic, prognostic, and therapeutic implications. Similar to TP53 mutations, oncogenic PTEN mutations can result from nonsynonymous missense mutations. However, there has been no detailed study on the immunostaining pattern of oncogenic PTEN missense mutations. METHODS: We retrospectively selected 18 cancers (13 endometrial cancers, 2 brain tumors, 1 ovarian cancer, 1 lung cancer, and 1 cancer of unknown origin) harboring oncogenic PTEN missense mutations, which were confirmed by targeted next-generation sequencing. PTEN immunohistochemistry was conducted for all cases, and the results were compared with sequencing results. RESULTS: The immunostaining results of PTEN missense mutations revealed a diverse pattern depending on the site of mutation and co-occurring mutation. The most frequent oncogenic PTEN mutations were R130G (4/18, 22.2 %) and R130Q (3/18, 16.7 %). Eleven cases harbored PTEN missense mutations only, whereas the remaining seven cases harbored PTEN truncating mutations and PTEN missense mutations. Complete loss of cytoplasmic expression were found in five cases, of which three had missense mutation only. PTEN R130 residue mutation alone did not showed altered PTEN immunostaining pattern in this study. CONCLUSIONS: PTEN missense mutation, which comprises a portion of oncogenic PTEN mutation, can manifest as a diverse immunostaining pattern. Complementary testing using both immunostaining and next-generation sequencing should be conducted to accurately evaluate the PTEN status in malignancy.

Biomarkers for Predicting Response to Personalized Immunotherapy in Gastric Cancer.

Despite advances in diagnostic imaging, surgical techniques, and systemic therapy, gastric cancer (GC) is the third leading cause of cancer-related death worldwide. Unfortunately, molecular heterogeneity and, consequently, acquired resistance in GC are the major causes of failure in the development of biomarker-guided targeted therapies. However, by showing promising survival benefits in some studies, the recent emergence of immunotherapy in GC has had a significant impact on treatment-selectable procedures. Immune checkpoint inhibitors (ICIs), widely indicated in the treatment of several malignancies, target inhibitory receptors on T lymphocytes, including the programmed cell death protein (PD-1)/programmed death-ligand 1 (PD-L1) axis and cytotoxic T-lymphocyte-associated protein 4 (CTLA4), and release effector T-cells from negative feedback signals. In this article, we review currently available predictive biomarkers (including PD-L1, microsatellite instability, Epstein-Barr virus, and tumor mutational burden) that affect the ICI treatment response, focusing on PD-L1 expression. We further briefly describe other potential biomarkers or mechanisms for predicting the response to ICIs in GC. This review may facilitate the expansion of the understanding of biomarkers for predicting the response to ICIs and help select the appropriate therapeutic approaches for patients with GC.

Clinical implications and chemo-sensitivity of adjuvant chemotherapy in patients with poorly cohesive cells-gastric cancer.

PURPOSE: Poorly cohesive cells-gastric cancer (PCC-GC) represents distinct features within the GC spectrum. The present study investigated the clinicopathologic characteristics and chemo-sensitivity for a relatively large cohort of PCC-GC patients. MATERIALS AND METHODS: A total of 268 patients diagnosed with stage II or III PCC-GC were included. GC cell lines were also analyzed for drug sensitivity to 5-fluorouracil (5-FU) and oxaliplatin in vitro. RESULTS: One hundred fifteen (42.9%) patients were stage II and 153 (57.1%) were stage III. Two hundred twenty-three (83.2%) patients received adjuvant therapy. Among these patients, 139 (62.3%) received CAPOX and 84 (37.7%) received S-1. With a median follow-up of 38.9 (1.6-137.8) months, the estimated 5-year disease-free survival (DFS) and overall survival (OS) rates were 52.3% and 61.0%, respectively. In the univariate analysis, survival was significantly better in the adjuvant chemotherapy group than in the surgery only group. In the subgroup analysis, there was no significant difference in DFS or OS between the types of adjuvant chemotherapy for either disease stage. In vitro cell line analysis, different responses to 5-FU and oxaliplatin were observed in SRC and non-SRC, where the treatment in KATOIII cell lines with oxaliplatin had less effect at a higher concentration compared to non-SRC cell lines. CONCLUSION: The current study found that adjuvant chemotherapy was not significantly associated with survival benefit for patients with resected stage II and III PCC-GC. Plus, S-1 showed numerically longer DFS and OS compared to CAPOX in PCC-GC patients, although no significant in the multivariate analysis.

Gastric cancer with distinct Epstein-Barr virus-positive and -negative tumor components and their whole exome sequencing result: a case Report.

BACKGROUND: Epstein-Barr virus (EBV)-associated gastric cancer exhibits distinct clinicopathologic characteristics, showing a good response to immune checkpoint inhibitors and a favorable prognosis. However, gastric cancer comprising distinct EBV-positive and -negative components in a single mass have been rarely reported, and their detailed genetic characteristics have not yet been investigated. Therefore, we reported the case of gastric cancer exhibiting distinct EBV-positive and -negative areas and further investigated its genetic characteristics. CASE PRESENTATIONS: A 70-year-old man underwent distal gastrectomy for gastric cancer, which was detected during a routine health check-up. EBV-encoded RNA in situ hybridization revealed distinct EBV-positive and -negative components at each other's borders, morphologically consistent with collision tumor. We separately sequenced EBV-positive and -negative tumor areas through whole exome sequencing (WES) with matched normal tissue. Remarkably, both EBV-positive and -negative areas shared pathogenic mutations of ARID1A, KCNJ2, and RRAS2. Furthermore, they shared 92 somatic single nucleotide variants and small insertion or deletion mutations, of which 32.7% and 24.5% are EBV-positive and -negative tumor components, respectively. CONCLUSIONS: WES results suggested that gastric cancer with distinct EBV-positive and -negative tumor components, formerly categorized as a collision tumor, can be clonally related. EBV-negative tumor component might be associated with loss of EBV during tumor progression.

Consensus Definition of Blood Samples from the Subcategorized Normal Controls in the Korea Biobank Network.

A control group is defined as a group of people used for comparison. Depending on the type of study, it can be a group of healthy people or a group not exposed to risk factors. It is important to allow researchers to select the appropriate control participants. The Korea Biobank Project-sponsored biobanks are affiliated with the Korea Biobank Network (KBN), for which the National Biobank of Korea plays a central coordinating role among KBN biobanks. KBN organized several working groups to address new challenges and needs in biobanking. The "Normal Healthy Control Working Group" developed standardized criteria for three defined control groups, namely, normal, normal-plus, and disease-specific controls. Based on the consensus on the definition of a normal control, we applied the criteria for normal control participants to retrospective data. The main reason for exclusion from the "Normal-plus" group was blood test results beyond 5% of the reference range, including hypercholesterolemia. Subclassification of samples of normal controls by detailed criteria will help researchers select optimal normal controls for their studies.

Atypical Radiological Findings of Capillary Hemangioma in Right Atrium: A Case Report.

BACKGROUND: Cardiac hemangiomas account for only 2.8% of primary cardiac tumors and are caused by the abnormal proliferation of endothelial cells and excess blood vessels. Typical radiological findings of cardiac hemangioma demonstrate intense contrast enhancement. CASE PRESENTATION: Here we report the case of a 69-year-old man who presented with a right atrial mass found incidentally with multimodal imaging findings, including echocardiography, computed tomography (CT), and magnetic resonance imaging (MRI). This case presented with poor enhancement within right atrial mass on dynamic contrast-enhanced CT scan and gadolinium-enhanced first-pass perfusion image of cardiac MRI. After surgical resection, the pathologic diagnosis of cardiac capillary hemangioma was made. CONCLUSION: Cardiac hemangioma could be included in the differential diagnosis for cardiac neoplasms demonstrating poor enhancements on CT and MRI scans.

Peritumoral imaging features of thymic epithelial tumors for the prediction of transcapsular invasion: beyond intratumoral analysis

PURPOSE: The purpose of this study was to differentiate cases without transcapsular invasion (Masaoka-Koga stage I) from cases with transcapsular invasion (Masaoka-Koga stage II or higher) in patients with thymic epithelial tumors (TETs) using tumoral and peritumoral computed tomography (CT) features. METHODS: This retrospective study included 116 patients with pathological diagnoses of TETs. Two radiologists evaluated clinical variables and CT features, including size, shape, capsule integrity, presence of calcification, internal necrosis, heterogeneous enhancement, pleural effusion, pericardial effusion, and vascularity grade. Vascularity grade was defined as the extent of peritumoral vascular structures in the anterior mediastinum. The factors associated with transcapsular invasion were analyzed using multivariable logistic regression. In addition, the interobserver agreement for CT features was assessed using Cohen's or weighted kappa coefficients. The difference between the transcapsular invasion group and that without transcapsular invasion was evaluated statistically using the Student's t-test, Mann-Whitney U test, chi-square test, and Fisher's exact test. RESULTS: Based on pathology reports, 37 TET cases without and 79 with transcapsular invasion were identified. Lobular or irregular shape [odds ratio (OR): 4.19; 95% confidence interval (CI): 1.53-12.09; P = 0.006], partial complete capsule integrity (OR: 5.03; 95% CI: 1.85-15.13; P = 0.002), and vascularity grade 2 (OR: 10.09; 95% CI: 2.59-45.48; P = 0.001) were significantly associated with transcapsular invasion. The interobserver agreement for shape classification, capsule integrity, and vascularity grade was 0.840, 0.526, and 0.752, respectively (P < 0.001 for all). CONCLUSION: Shape, capsule integrity, and vascularity grade were independently associated with transcapsular invasion of TETs. Furthermore, three CT TET features demonstrated good reproducibility and help differentiate between TET cases with and without transcapsular invasion.

PIK3CA Mutations as a Prognostic Factor in Patients With Residual Rectal Cancer After Neoadjuvant Chemoradiotherapy.

BACKGROUND/AIM: PIK3CA mediates various cellular processes, such as transformation, tumor initiation and proliferation, and resistance to apoptosis. This study was conducted to identify the clinical significance and prognostic effect of PIK3CA mutations in patients with residual rectal cancer who underwent surgery after neoadjuvant chemoradiotherapy (NACRT). PATIENTS AND METHODS: Formalin-fixed and paraffin-embedded surgical specimens were collected from 128 patients between January 2006 and December 2011 and analyzed using real-time polymerase chain reaction for hotspot mutations in exons 9 and 20 of the PIK3CA gene. RESULTS: Of the 128 patients, 109 were analyzed and 19 were excluded because of poor DNA quality. Mutations in PIK3CA were identified in three patients (2.8%), all of which were detected in exon 20 of the PIK3CA gene. PIK3CA mutations significantly correlated with lymphatic invasion (p=0.016), lymph node metastasis (p=0.034), and higher pathological disease stage (p=0.040). By univariate analysis, patients with PIK3CA mutations were observed to have significantly shorter cancer-specific survival (CSS) (p=0.001) and disease-free survival (DFS) (p=0.006) than PIK3CA wild-type patients. However, PIK3CA mutations were not an independent prognostic factor for CSS (p=0.319) or DFS (p=0.219) in multivariate modeling. CONCLUSION: Our findings indicate that PIK3CA mutation plays a role in oncogenesis in rectal cancer and may be considered as a candidate therapeutic approach targeting the PIK3/Akt/mTOR pathway in patients with residual rectal cancer after NACRT.

Plasma cell myeloma initially diagnosed as light-chain deposition disease on liver biopsy: A case report and literature review.

RATIONALE: Light-chain deposition disease (LCDD) is a rare condition characterized by the abnormal deposition of monoclonal light chains (LCs) in multiple organs, leading to progressive organ dysfunction. Herein, we report a case of plasma cell myeloma initially diagnosed as LCDD on liver biopsy performed for prominent cholestatic hepatitis. PATIENT CONCERNS: A 55-year-old Korean man complained of dyspepsia as the main symptom. On abdominal computed tomography performed at another hospital, the liver showed mildly decreased and heterogeneous attenuation with mild periportal edema. Preliminary liver function tests revealed abnormal results. The patient was treated for an unspecified liver disease; however, his jaundice gradually worsened, prompting him to visit our outpatient hepatology clinic for further evaluation. Magnetic resonance cholangiography revealed liver cirrhosis with severe hepatomegaly of unknown cause. A liver biopsy was performed for the diagnosis. Hematoxylin and eosin staining revealed diffuse extracellular amorphous deposits in perisinusoidal spaces with compressed hepatocytes. The deposits, which morphologically resembled amyloids, were not stained by Congo red but stained strongly positive for kappa LCs and weakly positive for lambda LCs. DIAGNOSES: Therefore, the patient was diagnosed with LCDD. Further systemic examination revealed a plasma cell myeloma. INTERVENTIONS: Fluorescence in situ hybridization, cytogenetics, and next-generation sequencing tested in bone marrow showed no abnormalities. The patient initially received bortezomib/lenalidomide/dexamethasone as the treatment regimen for plasma cell myeloma. OUTCOMES: However, he died shortly thereafter because of coronavirus disease 2019 complications. LESSONS: This case demonstrates that LCDD may present with sudden cholestatic hepatitis and hepatomegaly, and may be fatal if patients do not receive appropriate and timely treatment because of delayed diagnosis. Liver biopsy is useful for the diagnosis of patients with liver disease of unknown etiology.

Laparoscopic right hemicolectomy with aortocaval lymphadenectomy, and pelvic peritoneum partial resection for ascending colon cancer.

The aim of this video is to present the procedural details of laparoscopic right hemicolectomy with aortocaval (infrarenal aortic bifurcation) lymphadenectomy, partial resection of the pelvic peritoneum (peritoneal carcinomatosis index, 3), and hyperthermic intraperitoneal chemotherapy in a patient who received neoadjuvant chemotherapy for stage IVc colorectal cancer. The total operation time was 290 minutes, and the patient was discharged on a postoperative day 13 without any complications. No postoperative complications occurred until postoperative day 60. The pathological stage of the tumor was determined to be T3N2bM1c. The pelvic peritoneal nodule was pathologically confirmed as a metastatic lesion. Among the 12 harvested aortocaval lymph nodes, 6 were metastatic lymph nodes. The minimally invasive approach was safe and feasible in this highly selected patient with colon cancer, aortocaval lymph nodes, and peritoneal metastases.

A Standardized Pathology Report for Gastric Cancer: 2nd Edition.

The first edition of 'A Standardized Pathology Report for Gastric Cancer' was initiated by the Gastrointestinal Pathology Study Group of the Korean Society of Pathologists and published 17 years ago. Since then, significant advances have been made in the pathologic diagnosis, molecular genetics, and management of gastric cancer (GC). To reflect those changes, a committee for publishing a second edition of the report was formed within the Gastrointestinal Pathology Study Group of the Korean Society of Pathologists. This second edition consists of two parts: standard data elements and conditional data elements. The standard data elements contain the basic pathologic findings and items necessary to predict the prognosis of GC patients, and they are adequate for routine surgical pathology service. Other diagnostic and prognostic factors relevant to adjuvant therapy, including molecular biomarkers, are classified as conditional data elements to allow each pathologist to selectively choose items appropriate to the environment in their institution. We trust that the standardized pathology report will be helpful for GC diagnosis and facilitate large-scale multidisciplinary collaborative studies.

A standardized pathology report for gastric cancer: 2nd edition.

The first edition of 'A Standardized Pathology Report for Gastric Cancer' was initiated by the Gastrointestinal Pathology Study Group of the Korean Society of Pathologists and published 17 years ago. Since then, significant advances have been made in the pathologic diagnosis, molecular genetics, and management of gastric cancer (GC). To reflect those changes, a committee for publishing a second edition of the report was formed within the Gastrointestinal Pathology Study Group of the Korean Society of Pathologists. This second edition consists of two parts: standard data elements and conditional data elements. The standard data elements contain the basic pathologic findings and items necessary to predict the prognosis of GC patients, and they are adequate for routine surgical pathology service. Other diagnostic and prognostic factors relevant to adjuvant therapy, including molecular biomarkers, are classified as conditional data elements to allow each pathologist to selectively choose items appropriate to the environment in their institution. We trust that the standardized pathology report will be helpful for GC diagnosis and facilitate large-scale multidisciplinary collaborative studies.

Two cases of extramedullary plasmacytoma of the small intestine presenting with ileus: A case report.

BACKGROUND: Extramedullary (extraosseous) plasmacytoma (EMP) of the small intestine is a rare plasma cell neoplasm (PCN) that presents with abdominal pain, nausea, vomiting, etc. We describe 2 cases of EMP of the small intestine that presented with ileus. METHODS: A 78-year-old woman and 68-year-old man visited our clinic with complaints of abdominal discomfort and obstruction. Abdominal computed tomography (CT) revealed a thickened lesion with multiple enlarged mesenteric lymph nodes (LNs) in the ileum and duodenum. The female patient underwent segmental resection in the ileum. The male patient underwent Whipple's operation in the duodenum. RESULTS: Histopathological examination and immunohistochemical staining of resected specimens from the 2 patients confirmed a PCN. In the surgical specimens of 2 cases, immunoglobulin heavy-chain rearrangement was confirmed by polymerase chain reaction amplification, but no Epstein-Barr virus (EBV)-infected cells were found by EBV-in situ hybridization. Bone marrow aspirate and trephine biopsies were negative for the type of PCN. Bone marrow cytogenetics and fluorescence in situ hybridization revealed no abnormalities. Serum ß2-microglobulin levels were within normal limits. Additionally, none of the patients showed an M-spike in serum or urine protein electrophoresis. Therefore, the patients were diagnosed with a solitary EMP of the small intestine. The female patient refused treatment. At follow-up 3 months postoperatively, her disease progressed and she newly developed multiple LNs and nodular lesions in the right pelvic side wall. She was treated with dexamethasone. The male patient experienced back pain 25 days after Whipple's operation. Spine series magnetic resonance imaging revealed an intermediate signal intensity mass in the posterior epidural space from T8/9 to T10. The mass was removed, and the same histologic features were identified as duodenal masses. He was treated with dexamethasone and radiotherapy. CONCLUSIONS: EMPs of the small intestine are easy to overlook because they rarely occur in the small intestine. Although surgery is not required for diagnosis, surgical resection can be a good option for EMPs of the small intestine, instead of local radiation therapy. However, close follow-up is required due to the possibility of relapse or progression to plasma cell myeloma.