A case of diverticulum of the appendiceal base resembling a submucosal tumor of the cecum under colonoscopy: a hitherto undescribed lesion.

BACKGROUND: Diverticulosis of the appendix is an uncommon clinical entity, and a preoperative diagnosis is often difficult. Herein we report an unusual case of appendiceal diverticulosis. CASE PRESENTATION: A 72-year-old male was referred to our hospital to examine the cause of hematochezia. A colonoscopy study showed a protruding lesion resembling a submucosal tumor (SMT), approximately 20 mm in diameter, at the site around the appendiceal orifice of the cecum. An abdominal computed tomography and magnetic resonance imaging showed a cystic lesion at the appendiceal base. The lesion was clinically diagnosed as a cystic tumor of the appendix, but the possibility of a malignant tumor could not be excluded. Therefore, a laparoscopic ileocecal resection with lymph node dissection was performed. The pathological examination of the resected specimen revealed that the lesion was a diverticulum (pseudodiverticulum) occurring solitarily at the appendiceal base, in which the mucosal layer of the appendix was invaginated into the submucosa of the adjacent cecum, thus forming an SMT-like lesion. CONCLUSION: To our knowledge, this is the first case report in the English literature showing that an appendiceal diverticulum can manifest as an SMT-like lesion in the cecum. This condition should be recognized as a differential diagnosis for such lesions.

Possible spontaneous regression of hepatocellular carcinoma with unique histopathological features confirmed by surgical resection: a case report.

BACKGROUND: Spontaneous regression of hepatocellular carcinoma (HCC) is a rare event, and its clinicopathological features and underlying mechanism are not fully understood. CASE PRESENTATION: An 84-year-old female with hepatitis C virus infection and diabetes mellitus was referred to our hospital for further examination. Abdominal ultrasonography showed a 3.4-cm solid tumor with a heterogeneous irregular center and no fibrous capsule in liver segment 8 (S8). An enhanced computed tomography (CT) scan revealed a tumor in S8 with heterogeneous enhancement in the arterial phase and washed out insufficiently in the portal and equilibrium phase. The enhanced pattern on magnetic resonance imaging was similar to that of CT. Although the imaging findings were not typical for HCC, liver resection (S8) was performed with HCC as the most probable diagnosis. Histopathological examination of the resected specimen showed that the tumor was well to moderately differentiated HCC with unique features. Approximately half of the tumor was composed of well-differentiated HCC that was focally accompanied by dense lymphocyte infiltration. The other half of the tumor was fibrotic tissue that resembled an inflammatory pseudotumor. Several foci of moderately differentiated HCC were scattered within the tumor with a nodule-in-nodule appearance, and the foci totally showed coagulative necrosis. On immunostaining, lymphocytes in the tumor stroma were positive for CD8 and programmed death 1. The expression of programmed death-ligand 1 was observed in carcinoma cells and macrophages specifically within the lymphocyte-rich area of HCC. CONCLUSIONS: We consider this case representative of spontaneous regression of HCC, and the immune response against HCC might contribute to tumor regression, leading to complex histopathological appearances. This case may provide insight into the mechanism of spontaneous regression of HCC.

Heterotopic ossification in lymph node metastasis after rectal cancer resection: a case report and literature review.

BACKGROUND: Heterotopic ossification (HO) is the formation of osseous tissue outside the skeleton. HO in malignant tumors of the digestive tract is extremely rare, as is ossification in metastatic lesions from HO-negative digestive tract tumors. Regarding the pathogenesis of HO, two theories have been proposed. The first is that the osteoblastic metaplasia of tumor cells (driven by the epithelial-mesenchymal transition, EMT) results in HO, and the second is that factors secreted by cancer cells lead to the metaplasia of stromal pluripotent cells into osteoblasts. However, the osteogenic mechanisms remain unclear. CASE PRESENTATION: An 83-year-old Japanese woman underwent low anterior rectal resection for rectal cancer before presentation at our institution, in June 2018. The final diagnosis was stage IIB rectal adenocarcinoma (T4aN0M0). Histological examination did not reveal HO in the primary tumor. Thirteen months after the operation, a solitary metastatic lesion in the brain 20 mm in size and a solitary metastatic lesion in a right axillary lymph node 20 mm in size were diagnosed. The patient was treated with gamma-knife therapy for the brain metastasis. One month later, she was referred to our institution. She underwent lymph node resection. Histological examination revealed that most portions of the affected lymph node were occupied by metastatic tumor cells and that central necrosis and four small ossified lesions without an osteoblast-like cell rim were present in the peripheral region. Immunohistochemical analysis showed tumor cells positive for BMP-2, osteonectin, osteocalcin, AE1/AE3, TGF-ß1, Gli2, Smad2/3, and CDX2 and negative for nestin, CD56, and CK7. CONCLUSION: This is the first English case report of HO in a metachronous metastatic lymph node after the curative resection of HO-negative rectal cancer. Unlike HO lesions in past reports, the HO lesion did not show peripheral osteoblast-like cells, and the immunohistochemical findings indicated that the present case resulted from the EMT.

A Rare Case of Moderately Differentiated Adenocarcinoma With PD-L1 Overexpression and a Heterogeneous LELC Component in the Ascending Colon.

BACKGROUND: Lymphoepithelioma-like carcinomas (LELCs), especially colorectal cancers (CRCs), are uncommon pathological phenotypes generally associated with poor aggressiveness and a preferable prognosis. However, PD-L1 overexpression in CRCs is associated with poor outcomes. We report a case of moderately differentiated adenocarcinoma with PD-L1 overexpression, an LELC component, and Crohn's-like lymphoid reaction (CLR) presenting with extreme locoregional aggression and complete remission with chemotherapy after noncurative excision. CASE PRESENTATION: A 69-year-old man was referred to our hospital for abdominal fullness and pain. Computed tomography (CT) showed a circumferential tumor in the ascending colon, accompanied by bulky swollen lymph nodes. Under the preoperative diagnosis of T4N2M1 (lymph nodes) ascending colon cancer, we performed a right hemicolectomy; however, paracaval and parailiac vein lymph nodes were abandoned. Pathological findings showed moderate to poorly differentiated adenocarcinoma invading the subserosa accompanied by an LELC component invading the superficial muscularis propria. Lymph node metastases were found in a neighboring tumor and in retroperitoneal lymph nodes with glandular differentiation. No relation to microsatellite instability (MSI) or Epstein-Barr virus (EBV) was observed. In the component with glandular differentiation, PD-L1 overexpression was revealed. CLR findings were also observed. The tumor was diagnosed as T3N2M1 cancer that was moderately to poorly differentiated and had an LELC component. The patient was treated with chemotherapy, and the metastasized lymph nodes ultimately disappeared. He was alive without tumor recurrence 5-years post-operation. CONCLUSION: This is a very rare case of moderately differentiated adenocarcinoma with PD-L1 overexpression and a heterogeneous LELC component that developed in the ascending colon. Unlike the previously reported weak aggressive properties of LELCs, the present case showed an extremely aggressive locoregional extent, but complete remission was finally achieved with chemotherapy. This type of LELC with CLR could be associated with a good response to chemotherapy and a good prognosis in CRC patients.

Clinical characteristics of elderly pulmonary tuberculosis in an acute-care general hospital in Tokyo, Japan: A 12-year retrospective study.

OBJECTIVE: A significant feature of tuberculosis (TB) in Japan is the fact that a high proportion of cases belong to the elderly population. Furthermore, previous reports have pointed out the delayed diagnosis of pulmonary TB in acute-care settings. We aimed to examine the clinical characteristics of pulmonary TB patients in an acute-care general hospital, particularly focusing on the elderly population. METHODS: We retrospectively reviewed the medical records of patients with pulmonary TB who presented at our institution between May 2005 and December 2016. We described the overall clinical characteristics of these patients and compared them according to age. RESULTS: Overall, 289 patients were eligible for the analysis, with a median age of 58 [42-73] years, and 29.4% being older than 70 years. Among the elderly patients, 42.4% were characterized by atypical presentation. CONCLUSION: Our findings suggest that the elderly population tends to present as atypical cases lacking respiratory complaints, thereby being at a risk of misdiagnosis.

Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae ST258 isolated from a Japanese patient without a history of foreign travel - a new public health concern in Japan: a case report.

BACKGROUND: Thus far, studies on Klebsiella pneumoniae carbapenemase (KPC)-producing organisms have only been reported in those with a history of foreign travel, and a specific Japanese KPC-producing isolate has not yet been reported. CASE PRESENTATION: We describe a Japanese patient, with no history of travel to foreign countries, admitted due to aspiration pneumonia, and a KPC-producing isolate detected in his sputum. Fortunately, his pneumonia resolved. His close contacts did not have a history of foreign travel, and the isolate was not detected in other patients. CONCLUSIONS: The potential for KPC-producing organisms to become endemic in Japan is currently of great concern.

The first case report of infective endocarditis caused by Gemella taiwanensis.

Gemella is a facultative anaerobic Gram-positive coccus and a rare cause of infective endocarditis (IE). Gram staining may eventually misidentify the organism, which tends to easily decolorize and manifest as either Gram-negative or Gram-variable. Commercial biochemical tests are often used to identify Gemella, but the methods they employ sometimes lack accuracy. A 52-year-old woman was diagnosed with Gemella taiwanensis IE after initial identification of the pathogen as Gemella haemolysans using biochemical tests combined with matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). She was treated successfully with penicillin, gentamicin, and mitral valve replacement. To our knowledge, this is the first case of IE confirmed by 16S rRNA gene and groEL sequencing to have been caused by G. taiwanensis. The accurate diagnosis of rare or difficult-to-identify pathogens is a major challenge for clinical microbiological laboratories. The concurrent use of molecular methods could lead to the recognition of new or different pathogens.

Molecular epidemiological analysis of human- and chicken-derived isolates of Campylobacter jejuni in Japan using next-generation sequencing.

In this research, we analyzed the main sequence types (ST) and ST complexes of human- and chicken-derived isolates of Campylobacter jejuni in Japan by using multilocus sequence typing (MLST). We also analyzed lipooligosaccharide biosynthesis locus classes (LOS locus classes) and the numbers of isolates carrying genes coding resistance factors against various antibiotics, and observed their relationships. ST-21 complex was the main ST complex in isolates from humans (n = 38) and chickens (n = 25). None of the isolates showed resistance to imipenem, chloramphenicol, or erythromycin. Few isolates were resistant to ampicillin and streptomycin (1.3%-15%), whereas many showed resistance to tetracycline, ciprofloxacin, and nalidixic acid (38%-48%). Among the ST-21 complex isolates, ST4526 was detected at a very high rate. Those isolates showed resistance to tetracycline and ciprofloxacin, and were susceptible to ampicillin. Among the chicken-derived isolates, 37 of the 38 isolates that showed resistance to ciprofloxacin and nalidixic acid had threonine to isoleucine amino acid substitution in GyrA at codon 86 (T86I). Among the human-derived isolates, 17 of the 47 isolates that showed resistance to ciprofloxacin and 16 of the 48 isolates that showed resistance to nalidixic acid did not have T86I amino acid mutations in GyrA. The human-derived ST-21 complex isolates were classified into LOS locus classes A, B, C, D, and E. The chicken-derived ST-21 complex isolates, with the exception of one isolate, were all classified into LOS locus classes C and D. Among chicken-derived isolates, the most prevalent was ST51 (ST-443 complex) (10 isolates) and all of those were LOS locus class E.

Pseudo-SLE by human immunodeficiency virus infection.

A 61-year-old woman was admitted for long-lasting fever and recurrent opportunistic infections during the treatment of SLE. She had been diagnosed as SLE and type-IV nephritis based on a renal biopsy and serological findings. A colonoscopy and liver biopsy revealed disseminated Mycobacterium avium complex infection. Human immunodeficiency virus (HIV) infection status was then examined and found to be positive. From the clinical course, the first symptoms were inferred to have been those of HIV infection.

[A Case of Pathological Complete Response Following Neoadjuvant Chemotherapy with Gemcitabine plus Nab-Paclitaxel in Borderline Resectable Pancreatic Cancer].

We report a resected case with a pathological complete response(pCR)after neoadjuvant chemotherapy for borderline resectable pancreatic cancer(BRPC). A 67-year-old woman who had been treated for type 2 diabetes mellitus in our hospital presented with an exacerbation of diabetes. An abdominal CT scan confirmed a hypovascular mass in the pancreas body consistent with BRPC. After 3 courses of chemotherapy with gemcitabine plus nab-paclitaxel(GnP), her elevated DUPAN-2 level normalized. A follow up CT scan revealed that the tumor had decreased in size, and no distant metastasis was detected. Distal pancreatectomy with en-bloc celiac axis resection was performed. Histopathological examination of the resected specimens showed no evidence of residual cancer cells(pCR). The patient remains disease-free 8 months after surgery. Neoadjuvant GnP chemotherapy may be useful for BRPC.

Streptococcal toxic shock syndrome secondary to group A Streptococcus vaginitis.

Streptococcal toxic shock syndrome (TSS) is a systemic illness usually caused in the setting of infection by group A Streptococcus (GAS). The primary infections are often invasive infections of the respiratory tract or necrotizing infections of the skin and soft tissue, but some infections occur without relevant focus. GAS vaginitis is a rare condition among adult women and is accordingly thought to be uncommon as a cause of streptococcal TSS. Here we report the cases of two postmenopausal women with streptococcal TSS secondary to GAS vaginitis, one aged 55 and one aged 60. Both came to our emergency department with complaints or symptoms of abdominal pain, fever, hypotension, and multi-organ failure. In both cases, the relevant factor associated with streptococcal infection was a recent episode of GAS vaginitis. Both underwent fluid management and 14 days of antibiotic treatment and fully recovered without complications. Vaginitis was likely to be the primary infectious trigger of TSS in these two cases. Intrauterine device insertion, endometrial biopsy, and post-partum state have all been previously reported in TSS patients, and the female genital tract has been described as a portal of entry. GAS vaginitis warrants appropriate treatment as it may progress to severe systemic infection as described.

Needle-stick dengue virus infection in a health-care worker at a Japanese hospital.

OBJECTIVES: About 160 patients in Japan were infected with dengue virus by mosquito's bites in the summer and autumn of 2014. In this report, I describe a case of occupational dengue virus infection by needle-stick injury from the 1990s to alert health-care workers to the fact that dengue virus is among the causative agents responsible for occupational infectious disease even in Japan. CASE: A Japanese female in her thirties, a nurse at our hospital in Tokyo, was admitted to our hospital in January 1992 three days after the onset of fever, headache, and general malaise. She had never been overseas. Five days before the onset of her symptoms, she had pricked her finger with an injection needle used to draw blood from a febrile patient infected with dengue virus. She was diagnosed with dengue virus infection based on three findings: detection of the dengue virus genome in serum, isolation of dengue virus from serum, and serum samples positive for IgM antibodies against dengue virus. CONCLUSIONS: The patient contracted dengue virus infection via a needle-stick injury at our hospital. Although this occurred more than two decades ago, in 1992, health-care workers should still be mindful of the risk of dengue virus infection via needle-stick injury even in Japan.

Anterior mediastinal abscess diagnosed in a young sumo wrestler after closed blunt chest trauma.

Most mediastinal abscesses result from infections after thoracotomy, esophageal perforation or pene- trating chest trauma. This disease is rarely caused by closed blunt chest trauma. All previously reported such cases after closed blunt chest trauma presented with hematoma and sternal osteomyelitis resulting from sternal fracture. Here we report a 15-year-old sumo wrestler who presented with an anterior mediastinal abscess without any mediastinal fracture. The mediastinal abscess resulted from the hematogenous spread of Staphylococcus aureus to a hematoma that might have been caused by a closed blunt chest trauma incurred during sumo wrestling exercises.

Dengue-associated hemophagocytic syndrome in a Japanese traveler: a case report.

Hemophagocytic syndrome (HPS) can develop as a complication of dengue in rare cases, but its relationship with dengue is not well known. We report a case of dengue-associated HPS with liver involvement and coagulopathy. The patient, a Japanese female traveler who had recently returned from Thailand, had severe complications of dengue infection, but she recovered fully with symptomatic treatment.

Clinical presentation and diagnosis of toxoplasmic encephalitis in Japan.

Distinguishing life-threatening toxoplasmic encephalitis (TE) from brain lymphoma in patients with acquired immunodeficiency syndrome (AIDS) may be difficult. Empiric anti-toxoplasmosis treatment is often initiated because of the reluctance in performing brain biopsies, which may delay the diagnosis and treatment of brain lymphoma in Japan. In this study, we retrospectively examined the clinical characteristics of 13 AIDS patients with TE in Japan, including magnetic resonance imaging and thallium 201 (201TI) single photon emission computed tomography (SPECT) findings, cerebral spinal fluid analysis, serology, and polymerase chain reaction (PCR) results. All patients improved on anti-toxoplasmosis treatment. Of the 11 patients who underwent serological testing, 6 (55%) had a positive serological result. Of the 7 patients who underwent PCR testing, 3 (42.9%) had a positive PCR result. Nine of 11 patients with TE (81.8%) had multiple lesions. Analysis of the sites of TE lesions did not reveal a difference in site predilection between TE and brain lymphoma. Uptake was negative in all 9 patients who underwent 201Tl SPECT. The study findings suggest that toxoplasma serostatus and PCR may be used to discriminate TE from brain lymphoma. No focal accumulation of 201TI is strongly suggestive of TE in patients with AIDS in Japan.

Subjective adverse reactions to metronidazole in patients with amebiasis.

Subjective adverse reactions to metronidazole were analyzed in 111 patients with amebiasis. Metronidazole was administered to 36 patients at a daily dose of 2250 mg and 75 patients at daily doses lower than 2250 mg. The reactions reported included nausea without vomiting in 11 (9.9%) patients, nausea with vomiting in 2 (1.8%), dysgeusia in 2 (1.8%), diarrhea in 1 (0.9%), headache in 1 (0.9%), numbness in 1 (0.9%), dizziness in 1 (0.9%), urticaria in 1 (0.9%), exanthema in 1 (0.9%), and discomfort in 1 (0.9%). Nausea was reported by 28% (10/36) of the patients receiving metronidazole at a daily dose of 2250 mg and 4% (3/75) of the patients receiving lower daily doses. The duration of the metronidazole administration in days was not associated with the appearance of nausea. No life-threatening adverse reactions were identified, and good clinical therapeutic effects were observed in 96% (107/111) of the patients. While metronidazole appears to be a safe anti-protozoal agent for patients with amebiasis, our results indicate that a daily metronidazole dose of 2250 mg is excessive for amebiasis, as it often induces nausea.