Treatments for hemorrhoids include conservative treatment （dietary and lifestyle modification, medical treatment）, non-surgical office-based treatments, and surgery. Treatment options mainly depend on the degree of prolapse （Goligher's classification）. Conservative treatment should be recommended for all patients with hemorrhoids. Dietary and lifestyle modification means taking adequate fluids and fiber, and avoiding straining and a prolonged time on the toilet. Medical treatment is oral （flavonoids, for example） and topical medicine. The main goal of medical treatment is to control the symptoms. Office-based treatments include rubber band ligation, sclerotherapy （5% phenol in almond oil or aluminum potassium sulfate hydrate-tannic acid）, divided ligation procedure for hemorrhoids, and so on. There is no best treatment for hemorrhoids；when choosing a treatment, it is important to consider the disease grade, impact on quality of life, and the patient's personal preference, by shared decision-making.

Hemorrhoids are a benign disease and the basic treatment is outpatient conservative treatment or surgical treatment. However, outpatient treatment may not improve the symptoms, so surgical treatment such as ligation and excision in hospital should be considered. This article focuses on ligation and excision, which is the main surgical treatment performed in our hospital, a specialized proctology hospital. In addition, we discuss the reported procedures for prolapse and hemorrhoids, anal cushion lifting, hemorrhoidal artery ligation, and transanal hemorrhoidal dearterialization and the latest reported mucopexy-recto anal lifting technique. We discuss the points, precautions, and problems of these methods. Various methods for hemorrhoid surgery have been reported, but it is important to choose an appropriate technique based on an accurate understanding of the hemorrhoid condition, the presence of comorbidities, and the anatomy of the hemorrhoid and anus.

Treatments for anal fissures include non-surgical treatment and surgical treatment. Non-surgical treatments include lifestyle guidance, topical medications, defecation control, topical nitrates, calcium channel blockers, and botulinum toxin. This paper outlines these treatments. As state-of-the-art treatments, we describe new drugs for chronic constipation based on a new mechanism and chemical sphincterotomy by calcium channel blockers, including the trend in Japan. Non-surgical treatment is often considered as a pre-stage of surgical treatment, but it is also the basis of anal fissure treatment because it is related to maintenance of the condition after surgical treatment and prevention of recurrence.

Chronic anal fissure is a painful common proctological problem involving a tear in the epithelium of the anus. Conservative therapies are the first line in the treatment of anal fissures. However, medical managements are limited in Japan and surgery remains an effective and commonly used option for the treatment of chronic anal fissures. Surgical intervention for definitive treatment of chronic anal fissures is considered when conservative therapy fails. It is important to consider fecal incontinence after surgery when choosing surgery. Fecal incontinence associated with anal dilation and LIS have been reported. Anoplasty should be considered in patients with low pressure of the anal canal.

Operation methods for anal fistulas are generally classified into the lay-open technique, sphincter preserving technique, and seton technique. Although the lay-open technique is highly effective, it involves risks of post-operative anal deformation and disruption of anal function. Therefore, various sphincter-preserving techniques have been attempted in order to operate with less damage. Although it is impossible to prevent recurrence of fistula completely after sphincter-preserving technique surgery, various surgical techniques have been devised that may enhance curability. While treatment of the primary lesion has been considered to be essential for surgery for anal fistula, techniques that do not involve this have also been tried recently. The seton technique secures both anal function and curability, yet newly devised methods have also been reported.

Celiac disease is an immune-mediated systemic disorder triggered by dietary gluten in genetically susceptible individuals. Due to chronic inflammation mainly in the duodenum and jejunum, not only gastrointestinal symptoms such as abdominal pain and diarrhea, but also various symptoms such as depression present in these patients. Prevalence in Western countries is approximately 1%, while it is considered to be extremely rare in Asian populations including Japanese, though no large-scale study performed in an Asian country has previously been reported. We conducted a large-scale survey, which showed that the prevalence of celiac disease in a non-clinical population in Japan was low at 0.05%. Genetic factors such as HLA-DQ2,8 and environmental factors such as wheat intake amount are thought to influence celiac disease onset. Celiac disease is diagnosed by anti-tissue transglutaminase IgA antibody measurement and histological evaluation of specimens obtained by a duodenal biopsy procedure. The primary treatment for celiac disease is a gluten-free diet. Due to increasing wheat consumption in Japan, the prevalence of celiac disease is expected to increase, thus closer attention in clinical practice is warranted.

Chronic nonspecific multiple ulcers of the small intestine are a disease characterized by multiple small intestinal ulcers without any histopathologic specificity. It is caused by mutations in the SLCO2A1 gene, which encodes a prostaglandin transporter. The male-to-female ratio is 1：2, and the disease is intractable, causing anemia and hypoproteinemia. Intestinal resection is required in half of the cases. Small intestinal lesions are predominantly located at the ileum and are characterized by shallow ulcers and multiple stenoses in a circular or oblique pattern. In addition to the clinical course and morphological evaluation of the small intestinal lesions, the presence of upper gastrointestinal lesions and extra-gastrointestinal signs are helpful in the diagnosis, and the SLCO2A1 gene test is also useful.

Familial Mediterranean fever is an autoinflammatory bowel disease that causes repeated serous inflammation such as fever and abdominal pain due to a mutation in the MEFV gene. It is characterized by fever of 38°C or higher and serositis （abdominal pain, chest pain）, which lasts for half a day to 3 days, but may last up to a week. Blood tests show neutrophilia, erythrocyte sedimentation rate, CRP elevation, and serum amyloid elevation, and CT shows intestinal wall thickening, but none is specific. Gastrointestinal endoscopy may find intestinal lesions such as erosions and ulcers in the small and large intestines, and differentiation from IBD is required. The goal of treatment is to control symptoms and prevent amyloidosis, but in Japan, there are few complications of amyloidosis. Colchicine is successful in the majority of cases, but there are cases of resistance in which treatment with anti-IL-1β monoclonal antibody drugs and corticosteroids should be considered.

Myelodysplastic syndromes （MDS） are hematological disorders characterized by ineffective hematopoiesis of the bone marrow and are often associated with autoimmune diseases. In particular, it is believed that MDS with trisomy 8 （chromosome 8 abnormality） have intestinal disease of Behçet's or Behçet-like diseases. However, there are many differences, including clinical prognosis in trisomy 8-positive MDS cases compared with the clinical features of Behçet's disease. This article reviews the clinical features of intestinal disease seen in trisomy 8-positive MDS.

As immune-checkpoint inhibitors （ICI） are becoming standard therapies for various malignant tumors, increasing attention has been paid to their associated immune-related adverse events （irAEs）. The gastrointestinal tract is the major site of irAEs, and it has recently become evident that the large bowel is the most frequently affected region. Endoscopic findings of ICI-induced colitis include a reddish, edematous mucosa with increased mucous exudate, loss of normal vascularity and a granular mucosa. Histopathologic findings of ICI-induced colitis are expansion of the lamina propria, intraepithelial infiltration of neutrophils, crypt architectural distortion, neutrophilic crypt abscess and prominent apoptosis. The clinical, endoscopic and histopathological severity of ICI-induced colitis varies, but colonoscopy together with biopsy is essential for diagnosis. Colonoscopy with biopsy is the gold standard for the diagnosis of ICI-induced colitis. Endoscopists should be aware of the clinical features and pathophysiology of ICI-colitis for the prompt diagnosis and decision-making for treatment. Further prospective studies are needed to assess the efficacy of various medications including immunosuppressive regimens.

Mesenteric phlebosclerosis （MP） is a rare disease which causes chronic bowel ischemia mainly in the right side of the colon. Endoscopic features include characteristic mucosal discoloration （bronze to deep purple） and thickening of semilunar folds；ulcers are often observed also. Histology of mucosal biopsy shows deposition of collagen fibers in the lamina propria. Linear or branched calcifications of veins in and around the colonic wall and thickening of the colonic wall itself are also characteristic CT findings of MP. It has been shown that long-term use of herbal medicine including sanshishi is closely correlated with the development of MP. Major symptoms of MP are abdominal pain and diarrhea；however, a quarter of cases are asymptomatic. When disturbance of colonic passage becomes severe as the disease advances, surgery becomes necessary；about twenty per cent of cases have undergone surgery so far. However, cessation of herbal medicine including sanshishi often results in amelioration of lesions and avoidance of surgery. Although the carcinogenic potential of colonic mucosa in MP is not assumed at present, the association between MP and cancer should be examined in detail.