A 72-year-old man was diagnosed with tumors outside of the stomach and mesentery of the small intestine on abdominal computed tomography. Histopathological examination of an endoscopic ultrasound-guided fine-needle aspiration biopsy specimen confirmed the diagnosis of lymph node metastasis of a neuroendocrine tumor (NET). Gastroscopy, colonoscopy, small bowel capsule endoscopy, somatostatin receptor scintigraphy, and 18F-fluorodeoxyglucose positron emission tomography were performed. However, the primary lesion could not be diagnosed. The patient underwent surgery, and an ileal submucosal tumor, which was not identified preoperatively in addition to the aforementioned abdominal tumors, was detected. All tumors were diagnosed as NET, and the ileal tumor was considered the primary lesion. The patient has shown no recurrence postoperatively. The current study presents a case of an ileal NET with lymph node metastases in a patient in whom the primary lesion remained preoperatively undiagnosed.

A 53-year-old woman visited the hospital of this study complaining of constipation. Colonoscopy revealed a circumferential tumor with severe stenosis, and a computed tomography scan showed neoplastic lesions in the rectum and right breast area. Histology was poorly differentiated adenocarcinoma, requiring differentiation between type 4 and metastatic rectal cancer. Additional immunohistochemical tests were performed and a rectal metastasis of breast cancer diagnosis was made. Hormonal therapy was effective and the tumor volume was significantly reduced. Rectal metastasis of breast cancer is said to be rare. However, in the case of patients diagnosed with breast cancer or with a history of breast cancer, considering the possibility of gastrointestinal metastasis using histopathological examination is important.

A man in his thirties was admitted to the hospital because of upper abdominal pain. Computed tomography showed intussusception in the ascending and transverse colon. After spontaneous discontinuation, endoscopy revealed a 25-mm 0-I tumor in the ileum. An emergency operation was performed the next day due to intussusception recurrence. The tumor was hyperplastic intestinal epithelium with dendritic smooth muscle fascicles and partly cancerous. The patient had no clinical features of Peutz-Jeghers syndrome. Therefore, the patient was diagnosed with Peutz-Jeghers type polyps based on pathological findings. This case is considered to be a rare case of intussusception in the transverse colon due to Peutz-Jeghers type polyp with canceration.

Malignant melanoma is an aggressive tumor with a high potential for distant metastases. Autopsy studies have shown that gallbladder metastases are found in 15% of patients. However, metastatic melanoma of the gallbladder is rarely discovered in living patients. A 73-year-old man was reported. The patient underwent surgical removal of malignant melanoma on his back and lymphadenectomy of the axillary lymph nodes. In addition, the patient developed cutaneous metastases to the right axillary and the middle of the chest 1.5 years after the surgery. Consequently, nivolumab chemotherapy was started. A computed tomography (CT) scan showed a well-enhanced mass in the gallbladder 4 months after. Abdominal ultrasonography revealed a 13-mm hypoechoic heterogeneous mass in the gallbladder with a hyperechoic layer on the mass surface. Magnetic resonance imaging demonstrated that the gallbladder tumor showed high signal intensity on T1-weighted images, low signal intensity on T2-weighted images, and high signal intensity on diffusion-weighted images. Positron emission tomography-CT revealed the slight uptake of fluorodeoxyglucose at the tumor. Endoscopic ultrasonography showed a hypoechoic tumor infiltrating the submucosal layer. The patient underwent open cholecystectomy. Examination of the resected specimens revealed a black, nodular-type tumor in the gallbladder body. The histopathological diagnosis was malignant melanoma. It was judged as metastatic melanoma of the gallbladder.

The patient is a female in her thirties. The patient was diagnosed with pustular psoriasis during the treatment course for pneumonia with the appearance of small pustules of the skin and with an increase of serum total bilirubin level. Pustular psoriasis is a designated intractable disease with extremely low prevalence in which the skin of the whole body is flushed with high fever and many sterile pustules occur. This disease has been reported to be accompanied by liver dysfunction. Liver dysfunction appeared 1-2 weeks after the eruption appears in most cases, but this is the rare case in which the liver disorder precedes.

An 80-year-old woman was treated with pembrolizumab for non-small cell lung carcinoma. The hepatobiliary enzymes of the patient were elevated before the start of the ninth treatment cycle. The patient was diagnosed with pembrolizumab-induced sclerosing cholangitis based on magnetic resonance cholangiopancreatography and liver biopsy. Liver dysfunction improved with steroid therapy, and hepatobiliary enzymes increased again. The patient was treated with methylprednisolone (1000mg/day for 3 days) followed by oral prednisolone (1mg/kg/day). The patient's hepatobiliary enzymes subsequently decreased, and the oral prednisolone was tapered. Another liver biopsy, which showed a decrease in the hepatic CD8+ T cell count, was performed. Liver dysfunction did not recur although steroid therapy was discontinued after 1 year of administration.