Search

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.

A 60-year-old woman with neurofibromatosis type 1 presented to our hospital with melena. She reported a 1-year history of treatment with nilotinib hydrochloride hydrate for chronic myelogenous leukemia. Contrast-enhanced abdominal computed tomography revealed multiple intestinal tumors that were subsequently diagnosed as gastrointestinal stromal tumors (GIST) using single-balloon enteroscopy. Although the tumors showed no significant change over 1 year, partial jejunal resection was performed to confirm the diagnosis. Immunohistochemically, the tumors were GIST.

We report three cases of resected hepatocellular carcinomas with nodules showing different signal intensities in the hepatobiliary phase of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced MRI (EOB-MRI). One case involved a nodule-in-nodule type hepatocellular carcinoma that showed high signal intensity for the outer tumor and low intensity for the inner tumor in the hepatobiliary phase of EOB-MRI. The inner tumor was more dedifferentiated than the outer. The other two cases involved similar nodules, which showed different signal intensities in the hepatobiliary phase of EOB-MRI. In all three cases, the expression of OATP8 showed good correlation with high signal intensity in the hepatobiliary phase of EOB-MRI, whereas MRP2, MRP3, or both were also highly expressed. However, in the two nodules showing low intensities, the expression of one excreting transporter was independently high even though that of OATP8 was not high. The expression of excreting transporters is usually characterized by passive correspondence to OATP8 expression levels; nevertheless, it sometimes shows expression independent of OATP8.

We established a new method of purification and culture of mouse gallbladder epithelial cells. In primary culture, mouse gallbladder tissue was cultured on collagen gel using microexplant culture method; the epithelial cells spread in a single sheet from the microexplant toward the periphery on the collagen gel. Tiny fragment of the collagen gel containing the border of epithelial cell layer was retransplanted onto the another collagen gel for secondary culture. This retransplantation allowed the proliferation of the epithelial cells without mesenchymal contamination, which spread on the collagen gel at the rate of 0.29 +/- 0.06 mm per day for more than two weeks. The cultured epithelial cells showed cuboid or columnar shape with focal mucus production, which is morphologically and functionally similar to the in vivo epithelial cells. This suggests that this in vitro culture method can be used to pathophysiological studies of biliary epithelial cells as well as for the method of purification of the epithelial cells.

We established a new culture method of mouse gallbladder epithelial cells. Explantation of a tiny fragment of the mouse gallbladder (microexplant) on the collagen gel allowed the epithelial cells to proliferate on the collagen gel for more than 4 weeks. The epithelial cells spread in a monolayer sheet from the microexplant and extended onto the surface of the collagen gel 0.31 +/- 0.02 mm per day. Whereas, contaminated stromal cells proliferated under the epithelial cell layer and into the collagen gel. At the peripheral zone of epithelial sheet, the shape of the epithelial cells was squamous, and the cells were frequently positive for BrdU immunostaining, indicating the high proliferative activity. In contrast, the cells in the central part of epithelial sheet were cuboidal or low columnar in shape and showed well cell-polarity and mucus-secretory activity similar to the gallbladder epithelia in vivo. It was indicated that the cultured epithelial cells in this system preserved the morphological and functional differentiation to the physiological gallbladder epithelia. This newly established culture method has the characteristics of both the organ and the cell culture, and might be useful for the morphological and functional studies of the gallbladder epithelia in vitro.