Indolent feature of Helicobacter pylori-uninfected intramucosal signet ring cell carcinomas with CDH1 mutations

BACKGROUND

In Helicobacter pylori (Hp)-uninfected individuals, diffuse-type gastric cancer (DGC) was reported as the most common type of cancer. However, the carcinogenic mechanism of Hp-uninfected sporadic DGC is largely unknown.

METHODS

We performed whole-exome sequencing of Hp-uninfected DGCs and Hp-uninfected normal gastric mucosa. For advanced DGCs, external datasets were also analyzed.

RESULTS

Eighteen patients (aged 29-78 years) with DGCs and nine normal subjects (28-77 years) were examined. The mutation burden in intramucosal DGCs (10-66 mutations per exome) from individuals aged 29-73 years was not very different from that in the normal gastric glands, which showed a constant mutation accumulation rate (0.33 mutations/exome/year). Unbiased dN/dS analysis showed that CDH1 somatic mutation was a driver mutation for intramucosal DGC. CDH1 mutation was more frequent in intramucosal DGCs (67%) than in advanced DGCs (27%). In contrast, TP53 mutation was more frequent in advanced DGCs (52%) than in intramucosal DGCs (0%). This discrepancy in mutations suggests that CDH1-mutated intramucosal DGCs make a relatively small contribution to advanced DGC formation. Among the 16 intramucosal DGCs (median size, 6.5 mm), 15 DGCs were pure signet ring cell carcinoma (SRCC) with reduced E-cadherin expression and a low proliferative capacity (median Ki-67 index, 2.4%). Five SRCCs reviewed endoscopically over 2-5 years showed no progression.

CONCLUSIONS

Impaired E-cadherin function due to CDH1 mutation was considered as an early carcinogenic event of Hp-uninfected intramucosal SRCC. Genetic and clinical analyses suggest that Hp-uninfected intramucosal SRCCs may be less likely to develop into advanced DGCs.

Diagnostic performance of preoperative MR imaging findings for differentiation of uterine leiomyoma with intraligamentous growth from subserosal leiomyoma

PURPOSE

To evaluate the diagnostic performance of MRI findings for differentiating uterine leiomyoma with intraligamentous growth, or broad ligament fibroid, from subserosal leiomyoma.

METHODS

This study included 37 patients with surgically confirmed uterine smooth muscle tumors (36 leiomyomas and one smooth muscle tumor of uncertain malignant potential) with intraligamentous growth (IL) and size-matched control of 37 patients with subserosal leiomyoma (SS). Two radiologists independently evaluated eight preoperative MRI findings: tumor shape, degeneration, attachment to uterus, ovary elevation, ureter displacement, bladder deformation, rectal displacement, and separation of round ligament (RL) and uterine artery (UA). The diagnostic values of these findings and interobserver agreement were assessed. Receiver-operating characteristic (ROC) analysis of the number of positive MRI findings for diagnosing IL was performed. Clinical outcomes including surgical method, operation time, intraoperative blood loss, perioperative complications, and postoperative hospital stay of the two groups were compared.

RESULTS

Significant differences in tumor shape, attachment to uterus, ovary elevation, ureter displacement, and separation of RL and UA were found between IL and SS. Four of these findings, excluding ureter displacement, showed moderate to substantial interobserver agreement. When two or more of these four findings were positive, sensitivity, specificity, and area under the ROC curve were 91%, 77%, 0.90 in reader 1 and 82%, 89%, 0.91 in reader 2. The operation time was significantly longer for IL than for SS.

CONCLUSION

Tumor shape, attachment to uterus, ovary elevation, and separation of RL and UA are useful MRI findings for differentiating intraligamentous leiomyoma from subserosal leiomyoma.

Spinal cord astroblastoma with EWSR1-BEND2 fusion classified as HGNET-MN1 by methylation classification: a case report

The most recurrent fusion of central nervous system high-grade neuroepithelial tumor with MN1 alteration (HGNET-MN1) is MN1 rearrangement. Here, we report the case of a 36-year-old man with spinal cord astroblastoma showing Ewing Sarcoma breakpoint region 1/EWS RNA-binding protein 1 (EWSR1)-BEN domain-containing 2 (BEND2) fusion. The patient presented with back pain, gait disturbance and dysesthesia in the lower extremities and trunk. Magnetic resonance imaging showed an intramedullary tumor at the T3-5 level, displaying homogeneous gadolinium enhancement. Partial tumor removal was performed with laminectomy. Histological examinations demonstrated solid growth of epithelioid tumor cells showing high cellularity, a pseudopapillary structure, intervening hyalinized fibrous stroma, and some mitoses. Astroblastoma was diagnosed, classified as HGNET-MN1 by the German Cancer Research Center methylation classifier. MN1 alteration was not detected by fluorescence in situ hybridization (FISH), but EWSR1-BEND2 fusion was detected by FISH and RNA sequencing. Previously, a child with EWSR1-BEND2 fusion-positive spinal astroblastoma classified as HGNET-MN1 was reported. In conjunction with that, the present case provides evidence that EWSR1-BEND2 fusion is identified in the entity of HGNET-MN1. Taken together, the BEND2 alteration rather than MN1 may determine the biology of a subset of the central nervous system HGNET-MN1 subclass.

Papillary glioneuronal tumor growing slowly for 26 years: illustrative case

BACKGROUND

Papillary glioneuronal tumors (PGNTs) are classified as a type of World Health Organization grade I mixed neuronal-glial tumor. Most PGNTs involve cystic formations with mural nodules and solid components in the cerebral hemispheres, and PGNTs occur mainly in young adults. The long-term prognosis of PGNTs remains unclear.

OBSERVATIONS

A 38-year-old male had been diagnosed with an arachnoid cyst associated with epilepsy in a local hospital. The initial magnetic resonance imaging (MRI) study showed the tumor as a heterogeneously enhanced nodule in the left postcentral gyrus. Subsequent MRI studies showed slow growth of the tumor for 26 years. He underwent gross total resection to control his epilepsy. The histopathological findings revealed pseudopapillary structures involving hyalinized blood vessels with a single or pseudostratified layer of cuboidal glial cells with round nuclei and scant cytoplasm. At the periphery of the lesion, Rosenthal fibers and acidophilic granule bodies were observed in the gliotic brain tissue. Immunohistochemically, some interpapillary cells were positive for NeuN. On the basis of these findings, the tumor was diagnosed as a PGNT.

LESSONS

This PGNT showed slow growth for 26 years. When recognizing a slowly growing tumor in the cerebral hemispheres of relatively young people that is associated with epileptic seizures, PGNT should be considered as a differential diagnosis.

Necrotizing Funisitis as an Intrauterine manifestation of Cryopyrin-Associated Periodic Syndrome: a case report and review of the literature

BACKGROUND

Cryopyrin-associated periodic syndrome (CAPS) is a life-long, autoinflammatory disease associated with a gain-of-function mutation in the nucleotide-binding domain, leucine-rich repeat family, pyrin domain containing 3 (NLRP3) gene, which result in uncontrolled production of IL-1β and chronic inflammation. Chronic infantile neurologic cutaneous and articular (CINCA) syndrome/neonatal-Onset multisystem inflammatory disease (NOMID) is the most severe form of CAPS. Although the first symptoms may be presented at birth, there are few reports on the involvement of the placenta and umbilical cord in the disease. Therefore, we present herein a preterm case of CINCA/NOMID syndrome and confirms intrauterine-onset inflammation with conclusive evidence by using fetal and placental histopathological examination.

CASE PRESENTATION

The female patient was born at 33weeks of gestation by emergency caesarean section and weighted at 1,514 g. The most common manifestations of CINCA/NOMID syndrome including recurrent fever, urticarial rash, and ventriculomegaly due to aseptic meningitis were presented. She also exhibited atypical symptoms such as severe hepatosplenomegaly with cholestasis. The genetic analysis of NLRP3 revealed a heterozygous c.1698 C > G (p.Phe566Leu) mutation, and she was diagnosed with CINCA/NOMID syndrome. Further, a histopathological examination revealed necrotizing funisitis, mainly inflammation of the umbilical artery, along with focal neutrophilic and lymphocytic villitis.

CONCLUSIONS

The necrotizing funisitis, which only involved the artery, was an unusual observation for chorioamnionitis. These evidences suggest that foetal inflammation, probably due to overproduction of IL-1β, caused tissue damage in utero, and the first symptom of a newborn with CINCA/NOMID.

A multilocular thymic cyst associated with mediastinal seminoma: evidence for its medullary epithelial origin highlighted by POU2F3-positive thymic tuft cells and concomitant myoid cell proliferation

Multilocular thymic cyst (MTC) and germ cell tumors are common diseases that impact the mediastinum. Correctly diagnosing these diseases can be difficult because several other conditions can mimic them. We report a male patient with MTC associated with mediastinal seminoma. A needle biopsy of the mediastinal tumor revealed numerous epithelioid cell granulomas that mimicked sarcoidosis or mycobacterial infection. However, large atypical cells positive for Oct3/4 and KIT were noted between the granulomas; thus, we diagnosed the patient with mediastinal seminoma. The resected tumor, after chemotherapy, consisted of multiple cystic lesions, and a residual germ cell tumor was first considered. However, thymic medulla-specific elements, namely, POU2F3-positive thymic tuft cells and rhabdomyomatous myoid cells accompanying the epithelium, led to the correct diagnosis of MTC. Our case underscores the importance of recognizing the histological features associated with mediastinal seminoma and provides novel findings for MTC pathogenesis, namely, the presence of thymic tuft cells.

Chronic abruption-oligohydramnios sequence (CAOS) revisited: possible implication of premature rupture of membranes

AIM

The pathogenic mechanism of chronic abruption-oligohydramnios sequence (CAOS) remains unknown, and there are no objective standards for diagnosis on imaging or using pathological evidence. We aimed to reconsider and clarify the true pathology of CAOS by integrating clinical, magnetic resonance imaging (MRI) and histopathological findings of the placenta.

MATERIAL AND METHODS

This is a case series of patients with CAOS managed at our hospital between 2010 and 2020. The clinical data of the patients, including MRI findings and placental pathology, were reviewed retrospectively.

RESULTS

A total of 18 patients were eligible. Preterm birth occurred in 17 (94%) cases; the median gestational age at delivery was 25. Three neonates (17%) died within two years, and 10 neonates (56%) developed chronic lung disease. MRI was performed in 13 cases and clearly showed intrauterine hematoma and hemorrhagic amniotic fluid. Pathologically, in all cases, retroplacental hematoma was not detected, and fetal membranes were extremely fragile and ragged. Shedding and necrosis of the amniotic epithelium was a characteristic finding, which was confirmed in 17 cases (94%). Diffuse chorionic hemosiderosis (DCH) was detected in all cases.

CONCLUSIONS

The fundamental cause of CAOS is repeated intrauterine hemorrhage and subsequent subchorionic hematoma, which induces hemorrhagic amniotic fluid and DCH. Consequently, these factors result in the necrosis and weakening of the amnion. Therefore, the true pathology of CAOS is believed to be premature rupture of membranes rather than chronic abruption.

Sebaceous carcinoma of the vulva treated with sentinel lymph node biopsy: a case report and literature review

Sebaceous carcinoma (SC) is a rare and aggressive cutaneous malignancy. It often occurs on the eyelid, where it is called periocular SC, while extraocular SC mainly occurs on the head and heck. Extraocular vulvar SC is extremely rare; only nine cases have been described in the literature, and the optimal treatment strategy is unknown. We herein report a case of vulvar SC that was successfully treated with local excision in combination with sentinel lymph node biopsy (SNB). A 66-year-old female presented with vulvar discomfort. An 8 mm ulcerated mass was palpable in her left labia minora. Skin biopsy suggested SC. Imaging showed no swelling of the pelvic and inguinal lymph nodes and no metastasis. Sentinel lymph node scintigraphy using technetium-99 m showed three sentinel lymph nodes. The patient underwent local excision with SNB; intraoperative frozen-section examination revealed no nodal metastasis, and no further inguinal lymphadenectomy was performed. The final diagnosis was SC of the vulva, FIGO stage IB (pT1bN0M0). At the 14-month follow-up, she remained asymptomatic and had no signs of recurrence. The scientific rationale for SNB in extraocular SC has not yet been established, although SNB can be considered for periocular SC. However, considering the insufficient data on the management of vulvar SC and the aggressive nature of both periocular and extraocular SCs, SNB can be a reasonable and useful method for avoiding inadequate treatment and reducing the complications caused by unnecessary inguinal lymphadenectomy.

High-grade salivary gland carcinoma with the ETV6-NTRK3 gene fusion: A case report and literature review of secretory carcinoma with high-grade transformation

Secretory carcinoma or mammary analog secretory carcinoma is an entity of salivary gland carcinoma that is characterized by the ETV6-NTRK3 gene fusion. Although it is generally considered to be a low-grade malignancy, some cases of secretory carcinoma with high-grade transformation (SCHG) have been reported. We herein describe a case of SCHG composed almost exclusively of the high-grade component. The patient presented with a growing mass in the buccal mucosa and underwent surgery. Tumor cells showing high-grade nuclear atypia were arranged in solid or cribriform nests with comedo-like necrosis. A differential diagnosis included high-grade salivary gland carcinoma, such as salivary duct carcinoma. Immunohistochemically, tumor cells were focally positive for S-100 and negative for mammaglobin and showed nuclear positivity for pan-Trk. A reverse transcription polymerase chain reaction assay showed that the tumor harbored the ETV6-NTRK3 gene fusion. A histological review of microscopic slides of the tumor did not reveal a typical secretory carcinoma component, except for a very focal area. We ultimately diagnosed this tumor as SCHG. This case underscores the importance of recognizing the histological spectrum of SCHG and the utility of pan-Trk immunohistochemistry to detect secretory carcinoma, which may be targeted by tyrosine kinase inhibitors.

Mixed germ cell tumor infiltrating the pineal gland without elevated tumor markers: illustrative case

BACKGROUND

Tumors in the pineal region consist of various histological types, and correct diagnosis from biopsy specimens is sometimes difficult. The authors report the case of a patient with a mixed germ cell tumor infiltrating into the pineal gland despite showing no elevation of tumor markers.

OBSERVATIONS

An 18-year-old man complained of headache and nausea and showed disturbance of consciousness. Magnetic resonance imaging showed hydrocephalus associated with a cystic pineal tumor. The patient underwent tumor biopsy followed by endoscopic third ventriculostomy for hydrocephalus in a local hospital. A pineocytoma was diagnosed, and the patient was referred to the authors' hospital for treatment. Concentrations of placental alkaline phosphatase, alpha-fetoprotein (AFP), and beta-human chorionic gonadotropin in cerebrospinal fluid were not elevated. However, the authors' review of the tumor specimen revealed some immature cells infiltrating the pineal gland. These cells were positive for AFP, Sal-like protein 4, and octamer-binding transcription factor 3/4; and the diagnosis was changed to mixed germ cell tumor. Chemoradiotherapy was initiated, followed by surgical removal of the residual tumor.

LESSONS

Careful examination of all tumor specimens and immunohistochemical analyses are important for accurate diagnosis of pineal tumors.

Monoclonal gammopathy of renal significance (MGRS)-related AL amyloidosis complicated by amyloid myopathy: a case report

Background

Lately, monoclonal gammopathy of renal significance (MGRS) has been defined as a group of renal disorders that are strongly associated with monoclonal protein, including amyloid immunoglobulin light chain (AL) amyloidosis. Amyloid myopathy is rare (1.5% of all patients with amyloidosis) and the prognosis is poor. Furthermore, only approximately 20% of patients with amyloid myopathy are reported to have renal involvement, indicating a lack of data in the literature.

Case presentation

Here, we report a rare case of MGRS-related AL amyloidosis complicated by amyloid myopathy that presented with muscle weakness in the upper and lower limbs, neck and fingers, and nephrotic syndrome. Blood, urine, and bone marrow examination revealed monoclonal gammopathy of undetermined significance (MGUS) (Bence Jones protein-lambda). Muscle biopsy of the vastus lateralis muscle demonstrated amyloid proteins in the sarcolemma and in the blood vessel walls on Congo red staining, suggesting amyloid myopathy, and tiny inclusions in fibers on modified Gomori trichrome stain. Although we thought they were reminiscent of nemaline bodies, we could not confirm the nature of this structure. Renal biopsy demonstrated amyloid proteins in the mesangial region, part of the capillary walls, and the blood vessel walls on direct fast scarlet staining. As these amyloid proteins were positive for p-component staining and negative for amyloid A staining, β2-microglobulin, and pre-albumin, and as lambda light chains were positive in the mesangial region, we diagnosed the patient with MGRS-related AL amyloidosis. Although he was treated with melphalan and dexamethasone, his symptoms did not improve.

Conclusions

AL amyloidosis involving the kidneys and muscles has a poor prognosis, and a delayed diagnosis of amyloid myopathy is common because of its rarity and frequent misdiagnosis, which increases organ function deterioration. Therefore, early detection, therapeutic intervention, and careful follow-up are crucial.

A Novel Malignant Peritoneal Mesothelioma with STRN Exon 2 and ALK Exon 20: A Case Report and Literature Review

Recently, several malignant peritoneal mesotheliomas (MPMs), occurring in young women without asbestos exposure and with fusion genes such as anaplastic lymphoma kinase (ALK) and Ewing sarcoma breakpoint region 1, have been reported. In the present case, we encountered MPM with STRN-ALK fusion in a 17-year-old female adolescent. The case did not respond to chemotherapy and is currently in a clinical trial of alectinib. This is the fourth reported case of MPM with STRN-ALK fusion. Of the 45 cancer cases with STRN-ALK fusion in which the fusion partners were examined, all cases except for the current case showed fusion of exon 3 of STRN and exon 20 of ALK. This is the first case with fusion of exon 2 of STRN and exon 20 of ALK. Further advances in cancer genomic medicine may help clarify the clinical significance of this new fusion. KEY POINTS: Malignant peritoneal mesotheliomas (MPMs) can occur in young women without asbestos exposure and show fusion genes that activate anaplastic lymphoma kinase (ALK) by gene rearrangement. ALK rearrangement and the fusion partner can be detected by companion diagnostics and by next generation sequencing. Patients with MPMs with ALK rearrangement may benefit from target therapy.

Diffusion-weighted imaging of uterine adenomyosis: Correlation with clinical backgrounds and comparison with malignant uterine tumors

AIM

To elucidate correlation between signal intensity on diffusion-weighted images (SI-DWI) and clinical backgrounds for uterine adenomyosis and to compare SI-DWI of adenomyosis and malignant uterine tumors.

METHODS

This study examined 46 adenomyosis patients diagnosed using magnetic resonance imaging and 25 patients with surgically confirmed malignant uterine myometrial tumor. First, adenomyosis cases were classified visually into high-intensity and low-intensity groups based on the SI-DWI compared with that of normal uterine myometrium. Secondly, correlation was assessed between SI-DWI of adenomyosis and patient clinical background information such as age, menopausal status, menstrual cycle and dysmenorrhea severity. Third, quantitative comparison was made of low-intensity adenomyosis (LIA), high-intensity adenomyosis (HIA) and malignant tumor groups for the signal intensity ratio (SIR) on DWI and the apparent diffusion coefficient (ADC). Their diagnostic performance was evaluated using logistic regression analysis and receiver operating characteristic (ROC) analysis.

RESULTS

The 46 adenomyosis cases were classified as 26 low-intensity and 20 high-intensity cases. Significant correlation was found only for menstrual cycle phases. HIA had significantly lower SIR and higher ADC than malignant tumor. The ADC of HIA was significantly higher than that of LIA. The combination of SIR and ADC showed excellent diagnostic performance (area under ROC curve, 0.99).

CONCLUSION

There is a variation in signal intensity on DWI of uterine adenomyosis and it is associated with menstrual cycle phase. Adenomyosis with high signal intensity on DWI can be differentiated from malignant lesions by its lower signal intensity on DWI and higher ADC than that found for malignant uterine tumors, however overlaps exist.

Histological distribution pattern of hemosiderin deposition on the chorionic plate and fetal membrane of diffuse chorioamniotic hemosiderosis related to chronic abruption oligohydramnios sequence

INTRODUCTION

Chronic abruption oligohydramnios sequence (CAOS) is histologically characterized by diffuse chorioamniotic hemosiderosis (DCH). However, the criteria for the histological evaluation of the extent of CAOS-related hemosiderin deposition (HD) of the membranes and the difference in HD between the chorionic plate (CP) and fetal membrane (FM) are not well studied. This case control study compared the degree and distribution pattern of HD on CP and FM to present the histological features of DCH and the criteria for histological evaluation.

METHODS

From the medical records of Kyoto University Hospital (2010-2019), we selected 20 CAOS cases that were clinically diagnosed by Elliot's criteria. Twenty non-CAOS cases matched to the CAOS group by gestational age were selected as controls. We compared the clinical data and pathological features in the two groups. We performed iron staining in all the cases and analyzed HD in CP and FM according to the histological score (H-Score: 0-12), which was determined as the density (0-3) multiplied by the extent of staining (0-4).

RESULTS

HD was found in 100% (20/20) of CAOS and 15% (3/20) of control cases. In both the FM and CP, CAOS cases showed a significantly higher HS than control cases (CAOS, HS = 4-12; Control, HS = 0-1, p < 0.0001). Three CAOS patients presented HD alone in the CP. The HS of the CP was significantly higher than that of the FM (p = 0.0003).

DISCUSSION

CAOS presented DCH with HS ≥ 4. This study showed that the CP might be more suitable for evaluating DCH than the FM.

Severe fetal anemia as a consequence of extra-abdominal umbilical vein varix: A case report and review of the literature

Umbilical vein varix is associated with a high incidence of fetal anomalies and perinatal complications. There are two types of umbilical vein varix: fetal intra-abdominal and extra-abdominal. Herein, a case is reported of severe fetal anemia with extra-abdominal umbilical vein varix. A 33-year-old primigravida was referred to our hospital for fetal growth restriction, fetal cardiomegaly, and decreased fetal movements at 26 weeks' gestation. A Doppler assessment showed an elevated middle cerebral artery peak systolic velocity at 2.2 MoM, suggesting fetal anemia. Umbilical vein varix had caused intermittent turbulent flow, provoking hemolytic anemia. Intrauterine transfusion improved fetal circulatory failure and anemia and prolonged gestational period. At 33 weeks' gestation, the patient underwent cesarean delivery due to nonreassuring fetal status. Pathological analysis revealed focal loss of vascular smooth muscle of the umbilical vein. Extra-abdominal umbilical vein varix has been reported in 14 cases including this case. The antenatal diagnosis rate is reported to be 79%; fetal heartbeat abnormalities and fetal deaths were reported as 50% and 14%, respectively. Eighty-six percent of patients had intra-umbilical cord thrombosis, but currently this is the only case of hemolytic anemia. Furthermore, extra-abdominal umbilical vein varix may present as fetal hydrops with anemia. During ultrasound examination of fetal anemia, umbilical cord screening should be performed with caution.

Comprehensive genomic profiling for patients with chemotherapy-naïve advanced cancer

Comprehensive genomic profiling (CGP) testing by next‐generation sequencing has been introduced into clinical practice as part of precision cancer medicine to select effective targeted therapies. However, whether CGP testing at the time of first‐line chemotherapy could be clinically useful is not clear. We conducted this single‐center, prospective, observational study to investigate the feasibility of CGP testing for chemotherapy‐naïve patients with stage III/IV gastrointestinal cancer, rare cancer, and cancer of unknown primary, using the FoundationOne^® companion diagnostic (F1CDx) assay. The primary outcome was the detection rate of at least one actionable/druggable cancer genomic alteration. Actionable/druggable cancer genomic alterations were determined by the F1CDx report. An institutional molecular tumor board determined the molecular‐based recommended therapies. A total of 197 patients were enrolled from October 2018 to June 2019. CGP success rate was 76.6% (151 of 197 patients), and median turnaround time was 19 days (range: 10‐329 days). Actionable and druggable cancer genomic alterations were reported in 145 (73.6%) and 124 (62.9%) patients, respectively. The highest detection rate of druggable genomic alterations in gastrointestinal cancers was 80% in colorectal cancer (48 of 60 patients). Molecular‐based recommended therapies were determined in 46 patients (23.4%). CGP testing would be a useful tool for the identification of a potentially effective first‐line chemotherapy.

Nonsurgical Management Following Local Resection for Early Rectal Cancer in Patients with High-risk Factors: A Single-institute Experience

Objective

Additional surgery is considered for patients at high risk for lymph node metastasis (LNM) after local resection for early rectal cancer. Several factors are considered as indications for additional surgery, although there are currently no definitive criteria. This study aimed to clarify the need for additional surgery based on the number of risk factors for LNM and to evaluate the significance of submucosal invasion on recurrence.

Methods

Patients with early rectal cancer harboring risk factors for LNM who underwent local resection between March 2005 and December 2016 were retrospectively analyzed. Associations among the number of risk factors, prognosis, and additional treatment after local resection were investigated.

Results

A total of 29 eligible patients were classified into the surgery (n = 10), chemoradiotherapy (n = 7), and no-additional-treatment (NAT, n = 12) groups. Among the 29 patients, 15 patients (52%) with only one risk factor did not relapse. The NAT group harbored fewer risk factors for LNM, and 8 of the 12 patients (67%) had only deep submucosal invasion. Local recurrence occurred in one patient in the chemoradiotherapy group. The estimated 5-year overall survival rates were 88.9%, 75.0%, and 81.5% in the surgery, chemoradiotherapy, and NAT groups, respectively. There were no disease-specific deaths in the overall cohort.

Conclusions

In the present study, no recurrence occurred in patients who did not receive additional surgery with deep submucosal invasion as the only risk factor. A multicenter investigation is necessary to confirm the safety of nonsurgical options.

Upper Gastrointestinal Langerhans Cell Histiocytosis: A Report of 2 Adult Cases and a Literature Review

Langerhans cell histiocytosis (LCH) with primary involvement of the upper gastrointestinal (GI) tract is rare. We report 2 adult cases of localized LCH in the upper-GI tract, including the second reported adult case of esophageal LCH and review 11 previously reported cases. Case 1 involved the esophagus of a 61-year-old man; histiocytosis was detected when endoscopy was performed for an examination of epigastric pain. Case 2 involved the stomach of a 56-year-old woman wherein the lesion was detected during a follow-up endoscopy after Helicobacter pylori infection. Both biopsy specimens exhibited diffuse proliferation of mononuclear cells with nuclear convolution and a background of eosinophilic infiltrate. The cells were immunohistochemically positive for CD1a and langerin, and BRAF V600E mutation was detected in Case 2. Follow-up endoscopy for both cases revealed that the lesions disappeared without any treatment. It is important to avoid misdiagnosing LCH of the upper-GI tract as a malignant neoplasm.

Abstract 5877: Genetic analysis of metachronous pancreatic cancers

[Introduction] Early detection of pancreatic cancer is a key to curable surgery. However, many patients are diagnosed in an advanced stage and even in those cases who had a surgical resection of early stage tumors, metachronous pancreatic cancer in residual pancreas prevents cure. Thus, it is important to control metachronous tumors to improve clinical outcomes, whose pathogenesis is poorly understood. In this study, we aimed to reveal the origin of metachronous pancreatic cancers using an unbiased detection of somatic mutations in primary and metachronous cancers as well as adjacent precursor lesions. [Methods] Serially obtained formalin-fixed paraffin-embedded surgical specimens from 8 patient who had undergone curative surgery for an early stage pancreatic cancer were subjected to laser microdissection for the enrichment of tumor and PanIN lesions, from which DNA was extracted and analyzed for somatic mutations of each lesion by whole-exome sequencing (WES) with matched normal DNA. Based on shared and private mutations across different samples, we interrogated history of clonal evolution of these lesions. [Results] Pathology for primary cancer were margin-negative in all patients. The median interval between the initial and second surgery was 29.8 months (23 - 64.4 months). We analyzed a median of two cancer and one PanIN samples (0-5), from which we identified a median number of 45(range: 26-69) and 20 (14-42) somatic mutations using WES, respectively. None of the patients have known pathogenic germline variants. All samples had one or more driver mutations. In each patient, all driver mutations and more than half of passenger mutations were shared between primary and metachronous cancer samples, suggesting that those metachronous tumors are evolutionally closely related to the primary cancer. Negative pathology of the margins at the initial surgery suggested that those metachronous lesions originated from distant dissemination or metastasis, rather than contiguous, intraductal invasion. By contrast, none of the mutations other than hotspot KRAS mutations were shared between precursor lesions and cancer samples. Despite multiple independent clones in the precancerous lesion, all metachronous tumors originated from the primary lesions in this study. [Conclusions] Our study suggests that even early pancreatic cancer might be disseminated within the pancreas and contribute to metachronous cancers, suggesting the importance of close monitoring of the recurrence in the residual pancreas.

Citation Format: Hirano Tomonori, Nobuyuki Kakiuchi, Yasuhide Takeuchi, Yoshikage Inoue, Tomomi Nishimura, Yoichi Fujii, Akira Yokoyama, Hideki Makishima, Toshihiko Masui, Shinji Uemoto, Sachiko Minamiguchi, Hironori Haga, Kenichi Chiba, Hiroko Tanaka, Yuichi Shiraishi, Satoru Miyano, Norimitsu Uza, Yuzo Kodama, Hiroshi Seno, Seishi Ogawa. Genetic analysis of metachronous pancreatic cancers [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5877.