Repetitive patterns in rapid optical variations in the nearby black-hole binary V404 Cygni.

How black holes accrete surrounding matter is a fundamental yet unsolved question in astrophysics. It is generally believed that matter is absorbed into black holes via accretion disks, the state of which depends primarily on the mass-accretion rate. When this rate approaches the critical rate (the Eddington limit), thermal instability is supposed to occur in the inner disk, causing repetitive patterns of large-amplitude X-ray variability (oscillations) on timescales of minutes to hours. In fact, such oscillations have been observed only in sources with a high mass-accretion rate, such as GRS 1915+105 (refs 2, 3). These large-amplitude, relatively slow timescale, phenomena are thought to have physical origins distinct from those of X-ray or optical variations with small amplitudes and fast timescales (less than about 10 seconds) often observed in other black-hole binaries-for example, XTE J1118+480 (ref. 4) and GX 339-4 (ref. 5). Here we report an extensive multi-colour optical photometric data set of V404 Cygni, an X-ray transient source containing a black hole of nine solar masses (and a companion star) at a distance of 2.4 kiloparsecs (ref. 8). Our data show that optical oscillations on timescales of 100 seconds to 2.5 hours can occur at mass-accretion rates more than ten times lower than previously thought. This suggests that the accretion rate is not the critical parameter for inducing inner-disk instabilities. Instead, we propose that a long orbital period is a key condition for these large-amplitude oscillations, because the outer part of the large disk in binaries with long orbital periods will have surface densities too low to maintain sustained mass accretion to the inner part of the disk. The lack of sustained accretion--not the actual rate--would then be the critical factor causing large-amplitude oscillations in long-period systems.

Identification of characteristic subepithelial surface granulomatosis in immune-related adverse event-associated enterocolitis.

Immune checkpoint inhibitors (ICIs) have provided an additional treatment option for various types of human cancers. However, ICIs often induce various immune-related adverse events (irAEs). Enterocolitis is a major irAE with poorly understood histopathological characteristics. In this study, we retrospectively investigated the histopathology of colon tissue samples from 17 patients treated with ICIs. There were two major histological patterns of colitis: an ulcerative colitis-like pattern and a graft vs host disease-like pattern. Although these two patterns of colitis were mutually exclusive, both patterns often showed a characteristic that we call "subepithelial surface granulomatosis" (SSG), which has not been reported in other types of colitis. SSG was found even in colon tissue without symptoms or endoscopic findings of colitis. Given the increasing reports of sarcoid reaction or exacerbation of tuberculosis after treatment with ICIs, granuloma formation could be a histological hallmark of systemic immune activation by ICIs. Although statistical significance was not obtained, probably because of the small sample size, SSG may be a surrogate biomarker of systemic anticancer immune activation. We propose that a prospective study with larger sample size be performed.

[Radiotherapy for Alleviation of Paraparesis due to Leptomeningeal and Cauda Equina Metastasis of HER2-Positive Breast Cancer: A Case Report].

Leptomeningeal metastasis is a rare entity and its diagnosis is often difficult. Moreover, evidence-based therapeutic strategies have not yet been established. A 52-year-old woman presented with high fever and was diagnosed with bacterial meningitis at first examination;although her fever was alleviated, she experienced motor weakness in both of her lower extremities. Ga scintigraphy highlighted the hot-spot areas of the disease in the cranial bone. She was then transferred to our department. Open biopsy of the skull showed metastasis of the cancer. Chest CT results indicated right breast cancer and Gd-DTPA imaging showed obvious enhancement of the pia mater around the conus medullaris and cauda equina. However, cerebrospinal fluid(CSF)cytological examination did not show the presence of any positive cells;consequently, mastectomy was performed in the thoracic surgical department. The severity of paraparesis and pain in her legs increased;however, repeat MRI 1 month later showed no evidence of any change. Therefore, we performed biopsy of the cauda equina and arachnoid lesions. The pathological diagnosis was metastasis of breast cancer with positive human epidermal growth factor receptor 2(HER2)immunological staining. The results of a repeat cytological examination of the CSF during the surgery were negative. Local radiotherapy(25 Gy/5 Fr)as a monotherapy was selected for the patient, because her family did not approve of the combination of radiotherapy and chemotherapy. The severity of both paraparesis and limb pain decreased immediately after the radiotherapy.

[Colorectal carcinoma with hemiparesis due to isolated brain metastases as an initial symptom - a case report].

We present a rare case of colorectal carcinoma in which hemiparesis was the initial symptom. A 75-year-old woman presented with incomplete left-sided hemiparesis. Brain magnetic resonance imaging(MRI)revealed a 13-mm mass in the right frontal lobe; the mass was resected via craniotomy. Pathological findings, which included the results of immunohistochemical analysis, indicated brain metastasis from colorectal cancer. Colonoscopy revealed advanced colon cancer in the ascending colon, and computed tomography(CT)did not reveal any extracranial metastases. Left-sided hemicolectomy was performed. Whole-brain radiotherapy was scheduled, but before initiation of the therapy, metastases were detected in the neck lymph node and right arm skin, and the brain metastases relapsed. The relapsed brain metastatic lesions were resected, and radiotherapy was administered to the whole brain and the severely painful site of skin metastasis. However, the patient died 201 days after presentation. Historically, systemic chemotherapy was considered ineffective for metastatic brain tumor, and the standard treatments for brain metastasis were surgery and radiotherapy. Although recent advances in systemic chemotherapy for colorectal cancer have resulted in improved patient survival, patients with brain metastases from colorectal cancer still have a poor prognosis. Modern chemotherapeutic agents, including molecularly targeted agents such as bevacizumab, should be validated for the management of brain metastases.

[Gallbladder cancer with elevated serum α-fetoprotein, α-fetoprotein-L3, and human chorionic gonadotropin levels].

A 61-year-old woman presented with fever and was diagnosed with choledocholithiasis, which was removed endoscopically. Incidentally, a markedly elevated serum α-fetoprotein(AFP)level was detected(1,951 ng/mL), but computed tomography( CT)showed only diffuse gallbladder wall thickening. Subsequently, markedly elevated serum AFP-L3 and human chorionic gonadotropin(HCG)levels were detected(99.6%and 2,867mIU/mL, respectively). Fluorodeoxyglucose(FDG)- positron emission tomography/CT demonstrated high FDG uptake only in the gallbladder. Gallbladder cancer was suspected and the patient was scheduled for a cholecystectomy. However, CT just prior to surgery revealed multiple liver metastases. Percutaneous gallbladder biopsy revealed a moderately differentiated adenocarcinoma positive for AFP but not HCG. The patient underwent chemotherapy consisting of gemcitabine and cisplatin. A CT scan obtained 12 weeks later showed disease progression and AFP and HCG levels were found to have increased to 4,021 ng/mL and 66,000mIU/mL, respectively. Although immunohistochemistry of biopsy specimen did not demonstrate HCG production, increased serum HCG level on disease progression definitely suggested HCG production of gallbladder cancer. We believe the biopsy specimen was very small and therefore did not prove HCG production. Gallbladder cancer with simultaneous production of AFP and HCG is rare, and we therefore report this case together with a review of the literature.

[A case of a collision tumor comprising mucosa-associated lymphoid tissue lymphoma and early gastric cancer].

A 60-year-old woman underwent upper gastrointestinal endoscopy for an abnormality identified during routine examination. The lower gastric corpus showed a type 0-I elevated lesion with a faded mucosa and an area of converging mucosal folds in contact with the lesion. Biopsy indicated the former to be a high-grade adenoma and the latter to be a mucosa-associated lymphoid tissue (MALT) lymphoma. At the same time, Helicobacter pylori infection was diagnosed. Eradication therapy was administered to manage the MALT lymphoma; this resulted in improvement after 3 months. Endoscopic submucosal dissection was performed for the elevated lesion, and subsequent histopathology showed contact between the MALT lymphoma and gastric cancer. Therefore, the patient was diagnosed with a collision tumor. Concurrent cancers are increasingly reported and should be considered during examination.

Renal Mucinous Tubular and Spindle Cell Carcinoma Shows a High Uptake on 18F-FDG PET/CT.

We herein report a rare case of mucinous tubular and spindle cell carcinoma (MTSCC) in an 80-year-old woman. A well circumscribed tumor located on the right kidney was discovered incidentally as a result of screening non-contrast CT. Fluorodeoxyglucose positron emission tomography (FDG PET)/CT showed the increased tracer accumulation in the tumor. The histological diagnosis was MTSCC, which is a rare and only recently established subtype of the malignant renal cell carcinoma (RCC). The present case suggests the clinical benefit of a high uptake of FDG combined with enhanced contrast CT in the differentiation of MTSCCs and other RCCs.

Rare type of pancreatitis as the first presentation of anti-neutrophil cytoplasmic antibody-related vasculitis.

A pancreatic tumor was suspected on the abdominal ultrasound of a 72-year-old man. Abdominal computed tomography showed pancreatic enlargement as well as a diffuse, poorly enhanced area in the pancreas; endoscopic ultrasound-guided fine needle aspiration biopsy and endoscopic retrograde cholangiopancreatography failed to provide a definitive diagnosis. Based on the trend of improvement of the pancreatic enlargement, the treatment plan involved follow-up examinations. Later, he was hospitalized with an alveolar hemorrhage and rapidly progressive glomerulonephritis; he tested positive for myeloperoxidase-anti-neutrophil cytoplasmic antibody (ANCA) and was diagnosed with ANCA-related vasculitis, specifically microscopic polyangiitis. It appears that factors such as thrombus formation caused by the vasculitis in the early stages of ANCA-related vasculitis cause abnormal distribution of the pancreatic blood flow, resulting in non-uniform pancreatitis. Pancreatic lesions in ANCA-related vasculitis are very rare. Only a few cases have been reported previously. Therefore, we report our case and a review of the literature.

Loss of HER2 Positivity after Trastuzumab in HER2-Positive Gastric Cancer: Is Change in HER2 Status Significantly Frequent?

Trastuzumab has recently been introduced as a treatment for HER2-positive metastatic and/or unresectable gastric cancer (MUGC); however, compared with breast cancer, some issues concerning HER2 and trastuzumab therapy for gastric cancer remain unclear. A 74-year-old woman received trastuzumab-containing chemotherapy for HER2-positive MUGC. She had a marked response to 8 months of chemotherapy, and gastrectomy and hepatic metastasectomy with curative intent were performed. The resected specimen showed complete loss of HER2 positivity in the residual tumor. For MUGC, a change in HER2 status during the course of the disease with or without chemotherapy has rarely been reported. However, in breast cancer, a significant frequency of change in HER2 status during the course of disease has been reported, and reevaluation of HER2 positivity in metastatic/recurrent sites is recommended. The choice of trastuzumab for MUGC is currently based on the HER2 status of the primary tumor at the time of initial diagnosis, without reassessment of HER2 status during the course of disease and/or in metastatic/recurrent sites, on the assumption that HER2 status is stable. However, our case casts doubt on the stability of HER2 in gastric cancer.

Gastric T-cell lymphoma associated with hemophagocytic syndrome.

BACKGROUND: Lymphoma-associated hemophagocytic syndrome (LAHS) occurs in mostly extra nodal non-Hodgkin's lymphoma. LAHS arising from gastrointestinal lymphoma has never been reported. Here we report a case of gastric T-cell lymphoma-associated hemophagocytic syndrome. CASE PRESENTATION: A 51-year-old woman presented with pain, redness of breasts, fever and hematemesis. Hematological examination revealed anemia. Gastroscopy revealed small bleeding ulcers in the stomach and the computed tomography scan showed liver tumor. She underwent total gastrectomy for gastrointestinal bleeding and the histopathology revealed gastric T-cell lymphoma. She continued to bleed from the anastomosis and died on the 8th postoperative day. Autopsy revealed it to be a LAHS. CONCLUSIONS: If Hemophagocytic syndrome (HPS) occurs in lymphoma of the gastrointestinal tract, bleeding from the primary lesion might be uncontrollable. Early diagnosis and appropriate treatment are needed for long-term survival.

Gastric diffuse large B-cell lymphoma cured with Helicobacter pylori eradication regardless of whether it contains features of MALT lymphoma.

A 66-year-old patient was diagnosed with primary gastric B-cell lymphoma. The pathological findings were consistent with diffuse large B-cell lymphoma (DLBCL); however, a small area showed features of mucosa-associated lymphoid tissue (MALT) lymphoma. Biopsy specimens were referred to two other pathologists, both of whom diagnosed the case as pure DLBCL, denying the area of MALT lymphoma. As the lymphoma was limited to the submucosal layer and the patient's general condition was excellent, eradication of Helicobacter pylori was selected as the initial treatment. The lymphoma completely disappeared three months after the eradication treatment, and complete remission has been maintained for nearly two years.