Establishment and characterization of a novel neuroendocrine carcinoma cell line derived from a human ascending colon tumor.

The incidence of rare neuroendocrine tumors (NET) is rapidly increasing. Neuroendocrine carcinoma (NEC) is a NET with poorly differentiated histological features, high proliferative properties and associated poor prognoses. As these carcinomas are so rare and, thus, affect only a small number of patients allowing for few cell lines to be derived from patient biopsies, the histological, immunohistochemical, and clinical characteristics associated with colorectal NEC and NEC in other organs have yet to be clearly defined. Herein, we describe the establishment of a novel NEC cell line (SS-2) derived from a tumor resection of the ascending colon from a 59-year-old Japanese woman. The histological, electron microscopic and immunohistochemical features of chromogranin A (CgA) as well as confirmation of synaptophysin positivity in this tumor were typical of those commonly observed in surgically resected colorectal NEC. Further, the Ki-67 labeling index of the resected tumor was >20% and, thus, the tumor was diagnosed as an NEC of the ascending colon. The SS-2 cell line maintained characteristic features to those of the resected tumor, which were further retained following implantation into subcutaneous tissues of nude mice. Additionally, when SS-2 cells were seeded into ultra-low attachment plates, they formed spheres that expressed higher levels of the cancer stem cell (CSC) marker CD133 compared to SS-2 cells cultured under adherent conditions. SS-2 cells may, therefore, contribute to the current knowledge on midgut NEC biological function while providing a novel platform for examining the effects of colorectal NEC drugs, including CSC.

Characteristics predicting laparoscopic skill in medical students: nine years' experience in a single center.

INTRODUCTION: We introduced laparoscopic simulator training for medical students in 2007. This study was designed to identify factors that predict the laparoscopic skill of medical students, to identify intergenerational differences in abilities, and to estimate the variability of results in each training group. Our ultimate goal was to determine the optimal educational program for teaching laparoscopic surgery to medical students. METHODS: Between 2007 and 2015, a total of 270 fifth-year medical students were enrolled in this observational study. Before training, the participants were asked questions about their interest in laparoscopic surgery, experience with playing video games, confidence about driving, and manual dexterity. After the training, aspects of their competence (execution time, instrument path length, and economy of instrument movement) were assessed. RESULTS: Multiple regression analysis identified significant effects of manual dexterity, gender, and confidence about driving on the results of the training. The training results have significantly improved over recent years. The variability among the results in each training group was relatively small. CONCLUSIONS: We identified the characteristics of medical students with excellent laparoscopic skills. We observed educational benefits from interactions between medical students within each training group. Our study suggests that selection and grouping are important to the success of modern programs designed to train medical students in laparoscopic surgery.

[Clinicopathological characteristics and generational changes in metachronous gastric cancer of the reconstructed gastric tube].

This study investigated gastric tube cancer (GTC) to clarify the clinicopathological characteristics in different generations. We analyzed 165 cases with metachronous GTC; 9 cases from our institution and 156 from reported Japanese cases. Cases were divided into 3 groups to provide a detailed analysis of age-specific variations. GTC most commonly occurred in the lower gastric tube, and the most common histological type was tubular adenocarcinoma (70%). There were no age-related variations in the site and histological type of GTC. The incidence rate of endoscopic detection increased from 2003 to 74% in 2012, and the incidence of early GTC detection also significantly increased in this period. The rate of endoscopic treatment before 2003 was approximately 20%, and it doubled over the 10-year course of the study. The recent progress made in the diagnosis and treatment of GTC may have contributed to an improvement in its prognosis.

Lysosomal degradation of PD-L1 is associated with immune-related adverse events during anti-PD-L1 immunotherapy in NSCLC patients.

Background: Immune checkpoint inhibitors (ICIs) can induce immune-related adverse events (irAEs). Liquid biomarkers to predict irAE occurrence are urgently needed. We previously developed an ELISA system to specifically detect soluble PD-L1 (sPD-L1) with PD-1-binding capacity (bsPD-L1). Here, we investigated the relationship between sPD-L1 and bsPD-L1 in gastric cancer (GC) and non-small cell lung cancer (NSCLC) treated with PD-1/PD-L1 blockade and their association with irAEs. Methods: We examined sPD-L1, bsPD-L1, matrix metalloproteinases (MMPs), and proinflammatory cytokine levels by ELISA in plasma samples from 117 GC patients prior to surgery and 72 NSCLC patients prior to and at 2 months after ICI treatment (anti-PD-1, n = 48; anti-PD-L1, n = 24). In mice treated with anti-PD-1/PD-L1 antibodies (Abs), sPD-L1 levels and localization of Abs were examined by ELISA and immunohistochemistry, respectively. Results:sPD-L1 was detected with higher frequency in GC patients than in NSCLC patients, whereas bsPD-L1 was detected with similar frequencies in GC and NSCLC patients. sPD-L1 levels were correlated with IL-1α, IL-1ß, TNF-α, and IL-6 levels, while bsPD-L1 levels were correlated with MMP13, MMP3, and IFN-γ levels. In NSCLC patients, anti-PD-L1, but not anti-PD-1, treatment increased sPD-L1, which was associated with irAE development, but not with clinical outcomes. In mice, trafficking of anti-PD-L1 Abs to lysosomes in F4/80+ macrophages resulted in sPD-L1 production, which was suppressed by treatment with lysosomal degradation inhibitor chloroquine and macrophage depletion. Conclusion: Anti-PD-L1-mediated lysosomal degradation induces sPD-L1 production, which can serve as an indicator to predict irAE development during anti-PD-L1 treatment.

Combination of plasma MMPs and PD-1-binding soluble PD-L1 predicts recurrence in gastric cancer and the efficacy of immune checkpoint inhibitors in non-small cell lung cancer.

Background: The tumor microenvironment (TME) impacts the therapeutic efficacy of immune checkpoint inhibitors (ICIs). No liquid biomarkers are available to evaluate TME heterogeneity. Here, we investigated the clinical significance of PD-1-binding soluble PD-L1 (bsPD-L1) in gastric cancer (GC) patients and non-small cell lung cancer (NSCLC) patients treated with PD-1/PD-L1 blockade. Methods: We examined bsPD-L1, matrix metalloproteinases (MMPs), and IFN-γ levels in plasma samples from GC patients (n = 117) prior to surgery and NSCLC patients (n = 72) prior to and 2 months after ICI treatment. We also examined extracellular matrix (ECM) integrity, PD-L1 expression, and T cell infiltration in tumor tissues from 25 GC patients by Elastica Masson-Goldner staining and immunohistochemical staining for PD-L1 and CD3, respectively. Results: bsPD-L1 was detected in 17/117 GC patients and 16/72 NSCLC patients. bsPD-L1 showed strong or moderate correlations with plasma MMP13 or MMP3 levels, respectively, in both GC and NSCLC patients. bsPD-L1 expression in GC was associated with IFN-γ levels and intra-tumoral T cell infiltration, whereas MMP13 levels were associated with loss of ECM integrity, allowing tumor cells to access blood vessels. Plasma MMP3 and MMP13 levels were altered during ICI treatment. Combined bsPD-L1 and MMP status had higher predictive accuracy to identify two patient groups with favorable and poor prognosis than tumor PD-L1 expression: bsPD-L1+MMP13high in GC and bsPD-L1+(MMP3 and MMP13)increased in NSCLC were associated with poor prognosis, whereas bsPD-L1+MMP13low in GC and bsPD-L1+(MMP3 or MMP13)decreased in NSCLC were associated with favorable prognosis. Conclusion: Plasma bsPD-L1 and MMP13 levels indicate T cell response and loss of ECM integrity, respectively, in the TME. The combination of bsPD-L1 and MMPs may represent a non-invasive tool to predict recurrence in GC and the efficacy of ICIs in NSCLC.

[Prevention of nausea and vomiting in pain medication for digestive cancer].

Nausea and vomiting are common side effects due to opioid therapy, and may greatly impede the quality of life of cancer patients. A preventive method for nausea and vomiting has not yet been established. We developed a clinical pathway(CP) for cancer pain management in which prochlorperazine is used for the prevention of nausea and vomiting caused by opioids. We have shown that this CP is effective for relieving cancer pain. In this study, we investigated the efficacy prochlorperazine has for preventing nausea and vomiting caused by opioids in patients treated with the CP. The incidence of nausea and vomiting of those patients was 15. 8% which was lower than the results of other previous clinical trials. However, we could not show the effectiveness of prochlorperazine. Prochlorperazine, which is a dopamine D2 receptor antagonist, may show limited utility for the prevention of nausea and vomiting; however, in opioid therapy, histamine receptor(H1)prevention is also important.

[Evaluation of S-1 for stage IV gastric cancer].

To evaluate the efficacy of S-1 for Stage IV gastric cancer, we retrospectively examined 124 patients with Stage IV gastric cancer. We classified patients into two groups based on the presence or absence of S-1 administration: the S-1 therapy group (n= 56) and the non-S-1 therapy group (n=68). Basically, patients received S-1 orally at 40 mg per square meter of body surface area twice daily for 4 weeks, followed by 2 weeks without chemotherapy. When side effects appeared, we tried dose reduction or cut short the administering period according to the dose modification criteria. Major patient characteristics were as follows: gender (male/female: 76/48), and age (median[range]: 63[24-83]). The median S-1 dosage was about 5 courses, and the median of the S-1 total dosage was 10. 08 g, based on the amount of tegafur. The relative dose intensity (RDI) was well maintained (average: 74. 9%). The survival rate in the S-1 therapy group was significantly higher than in the non-S-1 therapy group. The median survival time (MST) was 308 days in the S-1 group and 157 days in the non-S-1 group. In the S-1 therapy group, the MST was 629 days for those receiving 10 g or more, while that of those receiving less than 10 g was 209 days. The MST of patients administered 10 g or more was significantly longer than that of those receiving less than 10 g (p<0. 0001). Therefore, we consider that S-1 therapy improves survival in patients with Stage IV gastric cancer.

A case of vascular Ehlers-Danlos syndrome with a ruptured hepatic artery after surgical treatment of peritonitis caused by the perforation of the colon.

BACKGROUND: Ehlers-Danlos syndrome (EDS) is an inherited disorder that causes connective tissue fragility. The vascular type of EDS (vEDS) caused by defective collagen type III production accounts for 5%-10% of all EDS cases. Patients can develop gastrointestinal or arterial ruptures, which cause poor prognosis. We report a case of a patient who experienced colonic rupture, which was immediately followed by arterial rupture. CASE PRESENTATION: A 40-year-old man who had been genetically diagnosed with vEDS 6 years previously was admitted to our hospital with ischemic colitis. After 3 days of conservative treatment, his abdominal pain worsened, and computed tomography (CT) revealed free air in the abdominal cavity. Pan-peritonitis due to perforation of the sigmoid colon was diagnosed. Intraperitoneal lavage and drainage and Hartmann's operation were urgently performed. Because the patient had confirmed vEDS, we performed the surgery in a protective manner. The postoperative course was initially good, and he was transferred to the general ward 3 days after surgery. However, 5 days after surgery, massive intra-abdominal hemorrhage suddenly occurred, and contrast-enhanced CT showed an aneurysm in the common hepatic artery that had ruptured; this aneurysm was not present before surgery and was far from the surgical field. Although we considered an emergency operation, the patient suddenly experienced cardiac arrest and was unresponsive to resuscitation. CONCLUSIONS: In cases of vEDS, vascular rupture can occur immediately after surgery for intestinal rupture. We recommend paying special attention to vascular complications in patients in their forties, as such complications are the most common causes of death.

Ligation and Fibrin Glue Spraying for Intractable Chylous Ascites after Radical Gastrectomy for Gastric Cancer: Case Report and Literature Review.

Chylous ascites associated with radical resection of gastric cancer is a serious clinical condition. Lymph node dissection is indispensable during gastrectomy for gastric cancer. However, postoperative chylous ascites prolongs the hospital stay and re-operation. There are few reports on this subject. Most cases of chylous ascites resolve without treatment, but the condition can result in substantial morbidity. The definition of chylous ascites is ambiguous and varies in the English literature. In this report, we discuss a case of chylous ascites in a 68-year-old man who underwent distal gastrectomy for early gastric cancer at our hospital. He was admitted 8 months after surgery with a main complaint of abdominal swelling. Abdominal puncture helped to diagnose chylous ascites with marked elevation of triglyceride level. The patient received a hypercaloric infusion through a central line, and octreotide acetate, but did not improve. After assessment of lymph outflow by lymph scintigraphy, surgical ligation of the lymph vessels was performed through laparotomy. The volume of milky-white ascites in the abdominal cavity was 3,000 mL. Macroscopically, the fluid was confirmed as flowing from behind the common hepatic artery. Thus, ligation was performed. Chylous ascites has not recurred at 12 months after the re-operation. In summary, a case of chylous ascites after radical gastrectomy for gastric cancer was successfully treated by surgery. We review and discuss the relevant literature.

Treatment of Gastric Cancer in Japan.

Although the incidence of gastric cancer has decreased because of the lower rate of Helicobacter pylori infection, it still accounts for a large number of deaths in Japan. Gastric cancer is mainly treated by resection, and the rate of radical resection is high in Japan because approximately 50% of cases are diagnosed at an early stage. Treatment advances have increased the number of endoscopic submucosal dissections, and development of laparoscopic surgery and robot-assisted surgery as minimally invasive approaches has yielded results similar to those of conventional surgeries, at least in the short term. Cases for which resection is contraindicated are treated with chemotherapy if performance status can be maintained. Although anticancer drugs are continuously under development, treatment outcomes remain unsatisfactory. As Japan becomes a super-aging society, the number of refractory cases is projected to increase. Therefore, evidence of any benefit for minimally invasive surgery and function-preserving surgery needs to be reported quickly. In this paper, we discuss gastric cancer treatment modalities recommended in the fifth edition of the gastric cancer treatment guidelines and describe recent research findings.

Preoperatively diagnosed gastric collision tumor with mixed adenocarcinoma and gastrointestinal stromal tumor: a case report and literature review.

Reports of gastric collision tumors, comprising adenocarcinoma and gastrointestinal stromal tumor, are extremely rare. Here, we report the case of a 68-year-old male who was diagnosed with a lower-body, moderately differentiated, tubular-type adenocarcinoma and submucosal tumor and underwent an elective D2 distal gastrectomy. The tumor cells of the gastrointestinal stromal tumor were positive for H-caldesmon and CD117, weakly positive for smooth muscle actin and DOG-1, and negative for desmin, S-100 protein, CD31, and AE1/AE3. The tumor had grown into a mixed form of adenocarcinoma and gastrointestinal stromal tumor. Thus, we report the first case of a preoperatively diagnosed collision tumor in the stomach consisting of adenocarcinoma and gastrointestinal stromal tumor.

An advanced case of gastric histiocytic sarcoma treated with chemotherapy and gastrectomy: a case report and review of literature.

Histiocytic sarcoma is a relatively new disease category and the gastrointestinal origin is sporadic. We report a case of a 74-year-old woman who underwent chemotherapy and proximal gastrectomy for extremely rare, advanced gastric histiocytic sarcoma. The resected specimen was subjected to numerous immunostainings to meet the diagnostic criteria of histiocytic sarcoma and was positive for the histiocyte markers' cluster of differentiation 68 and lysozyme. The markers of Langerhans cells, follicular dendritic cells, and myelocyte were all negative. Six reports of surgical resection of histiocytic sarcoma originating in the stomach exist, including our case. We reviewed the clinical course and the histological and immunohistochemical diagnostic features of surgically resected gastric histiocytic sarcoma.

[Effects of irinotecan and 5-FU combination therapy in gastric cancer--is combination therapy synergic?].

UNLABELLED: The response rate of Irinotecan for gastric cancer is reported to be 18. 4%. The rate is improved by combination with 5-FU. However, it remains unclear whether or not the effect of the two drugs is synergy or antagonistic. The purpose of this study is to clarify whether the effect of Irinotecan and 5-FU in gastric cancer is synergy or antagonistic. We performed study using 13 specimens removed surgically and 2 specimen collected from ascites. We performed the Collagen Gel Droplet Embedded Culture Drug Sensitivity Test (CD-DST) with 3 assumptions. In the first assumption, we let 5-FU come in contact with a tumor at a level of 1 mg/mL for 24 hours. The second assumption was SN-38 at a level of 30 mg/mL for 24 hours and the 3rd assumption was SN-38 at a level of 30 mg/mL and 5-FU at a level of 1 mg/mL for 24 hours. If the combination index was more than 1, the combination therapy was judged as synergic; if less than 1, it was considered antagonistic. RESULTS: The inhibition rate of combination therapy was significantly higher than that of monotherapy. The inhibition rate of combination therapy was significantly correlate with that of monotherapy (Irinotecan; r=0.704, p=0.003, 5-FU; r=0.746, p=0.001). The combination index was antagonistic in only 6 of 15 cases. However, it was synergic in all well-differentiated adenocarcinomas (4/4). DISCUSSION: We conclude that combination therapy is antagonistic in most cases of gastric cancer in vitro. However, it may be synergic in well-differentiated adenocarcinomas.

Skeletal Muscle Mass Depletion After Gastrectomy Negatively Affects the Prognosis of Patients With Gastric Cancer.

BACKGROUND/AIM: Skeletal muscle mass (SMM) is often depleted in patients with gastric cancer undergoing gastrectomy. Using a novel method, we evaluated the effect of SMM depletion after gastrectomy on disease prognosis. PATIENTS AND METHODS: The maximum cross-sectional area of the psoas-muscle (MCA-PM) was measured before surgery and at 1 year after in 233 patients with gastric cancer who underwent radical gastrectomy to determine the ratio (MCA-PMR) as an indicator of SMM depletion. RESULTS: The MCA-PMR cutoff value was set at 90%, and patients were divided into the groups with <90% and ≥90%. MCA-PMR <90% was an independent prognostic factor for all patients. In 88 patients who received adjuvant chemotherapy including S-1, the 5-year cancer-specific survival rate was significantly better for those with MCA-PMR ≥90% than for those with MCA-PMR <90% (84.1% vs. 59.1%; p=0.010; hazard ratio=2.974; 95% confidence interval=1.241-7.124). CONCLUSION: SMM depletion after gastrectomy can be measured using the MCA-PMR. This novel measurement can be easily implemented in the clinical setting.

Liver cyst with biliary communication successfully treated with laparoscopic deroofing: a case report.

A 56-year-old woman visited our hospital because of high fever and right hypochondralgia. Abdominal computed tomography showed a liver cyst 10 cm in diameter and dilatation of the intrahepatic bile duct. Percutaneous transhepatic drainage of the cyst guided by ultrasonography disclosed that the cyst contained a brown milky fluid, and cystography showed biliary communication. Thus, the cyst was diagnosed as an infectious hepatic cyst with biliary communication. Treatments for liver cysts include aspiration therapy, alcoholic sclerotherapy, laparoscopic fenestration, fenestration by laparotomy, cystojejunostomy, cystectomy, and hepatectomy. Because a simple liver cyst is benign, treatments should be low-risk and minimally invasive; thus, we performed laparoscopic fenestration. Fenestration should not be performed if the case is complicated by infection or biliary communication. Although cystography showed biliary communication, the cyst was not visualized with endoscopic retrograde cholangiography, and we concluded that the biliary communication was small. Operation time was 95 minutes, and blood loss was 10 g. Pathological findings of the liver cyst were consistent with a simple cyst. The postoperative course was good, and the patient left the hospital 10 days after the operation. Eighteen months have passed since the operation, and no recurrent cysts have been detected with computed tomography. This is the second report of liver cyst with biliary communication successfully treated with laparoscopic deroofing. Laparoscopic fenestration is a useful method for treating simple benign liver cysts because of its minimal invasiveness and may be useful in cases with small biliary communication.

Correlation between clinical pathologic factors and activity of 5-FU-metabolizing enzymes in colorectal cancer.

INTRODUCTION: Orotate phosphoribosyl transferase (OPRT), dihydropyrimidine dehydrogenase (DPD), and thymidylate synthase (TS) are initial key enzymes in the 5-fluorouracil (5-FU) metabolic pathway. The expression levels and activities of these three enzymes play important roles in the response of cancer patients to 5-FU-based chemotherapy. PURPOSE: The purpose of this study was to investigate the relationship between the activities of 5-FU metabolic enzymes and clinicopathologic factors in colorectal cancer. METHODS: We measured the activities of OPRT, DPD, and TS in colorectal cancer tissues. We also investigated the correlations between the activities of these three enzymes and clinicopathologic factors (histological type, depth of tumor invasion, extent of lymph node metastasis, Dukes' stage, lymphatic invasion, and vascular invasion). We examined 100 patients with surgically resected colorectal cancer. RESULTS: Poorly differentiated adenocarcinoma showed significantly higher DPD activities than did moderately differentiated or well-differentiated adenocarcinoma. In patients with lymph-node metastasis, OPRT activity was significantly lower than in patients without lymph-node metastasis. No significant relation was found between TS activity and histological type, depth of tumor invasion, extent of lymph node metastasis, Dukes' stage, lymphatic invasion, or vascular invasion. CONCLUSION: The response to 5-FU may be poor in patients with lymph-node metastasis, because of low OPRT activity, and in patients with poorly differentiated adenocarcinoma, because of high DPD activity.

Male choriocarcinoma with metastasis to the jejunum: a case report and review of the literature.

We report on a patient with male choriocarcinoma. The patient was a 31-year-old male patient with jejunal choriocarcinoma that metastasized from the mediastinum. He was admitted complaining of melena and severe anemia. Upper and lower gastrointestinal endosocopy was performed, but no source of bleeding was seen. Chest X-ray and CT revealed a mediastinal tumor 7 cm in size anterior to the arotic arch. Superior mesenteric arteriography showed irregularities and macular opacity in the jejunal artery. An emergency laparatomy was performed because of massive gastrointestinal bleeding. A jejunal tumor approximately 4 cm in size was resected and numerous metastases were observed in the liver and mesentery. Histopathological examination showed metastatic jejunal choriocarcinoma. Gynecomastia was not present and the testes were normal. Serum beta-human chorionic gonadotropin (HCG) was at an abnormally high level of 4,396 ng/mL. Because of metastases to the brain and invasion to the trachea, he died on postoperative day 20. We report this rare case of a male patient with metastases of choriocarcinoma to the gastrointestinal tract from the mediastinum, together with a review of the literature.

[Antitumor effect of paclitaxel for gastric cancer is AUC dependent].

Paclitaxel (PTX), which is used for ovarian cancer, lung cancer, breast cancer and gastric cancer, is administered at a dose of 210 mg/m(2) once every three weeks. However, WHO grade 3-4 hematological and non-hematological toxicity occurred frequently in this manner. In recent studies about ovarian cancer and lung cancer, a schedule in which PTX was given weekly could have the same or better efficacy, with fewer side effects. The response rate of PTX administered every three weeks for gastric cancer, was 23.3 to approximately 28.0%, while that of PTX administered weekly was 24.0 to approximately 25.8%. Because of fewer adverse events, weekly PTX is widely used for gastric cancer in Japan. To prove the validity of PTX weekly administration, we performed a study using six specimens removed surgically and one specimen collected from ascites. A chemosensitivity test was performed on the basis of two assumptions: a high concentration for a short time, and a low concentration for a long time. A similar PTX effect was obtained when the AUC was equal. In this study, we demonstrated that the effect of low-dose PTX was equal to the effect of high-dose PTX in gastric cancer.

Long-term survival after multidisciplinary therapy for brain metastases from asymptomatic esophageal adenocarcinoma.

Asymptomatic T1 (invaded submucosa) esophageal carcinoma rarely metastasizes to the brain. A 53-year-old Japanese man complaining of right hemiparesis and convulsion was admitted to our hospital. Brain imaging demonstrated a ring-like, enhanced brain tumor in the left parietal lobe. The pathological findings of the resected tumor were consistent with a metastatic adenocarcinoma from the gastrointestinal tract. Additional examinations revealed an elevated-type tumor in the lower third of the thoracic esophagus. The patient underwent thoracoscopic esophagectomy with lymph node dissection followed by reconstruction with gastric tube substitution. The immunohistochemical findings of the resected specimen were similar to those of the metastatic brain tumor. Although the patient received adjuvant chemotherapy (5-fluorouracil, docetaxel plus cisplatin), a solitary small brain metastasis was detected 4 months after esophagectomy. Excision of the sequential metastases with whole-brain radiation therapy and gamma-knife therapy were performed. The patient survived for 50 months after beginning the initial treatment. This report describes a rare case of brain metastases from T1 esophageal adenocarcinoma in a patient without gastrointestinal symptoms.

Case of rectal malignant melanoma showing immunohistochemical variability in a tumor.

We report on a patient with rectal malignant melanoma. The patient was a 40-year-old man who complained of anal bleeding. His grandmother had died of pancreatic cancer and his mother had been operated for rectal cancer. Physical examination revealed a hard mass at the 12 o'clock position, 2 cm from the anal verge. A colonoscopic examination revealed an irregular surface mass, approximately 4.0 cm in size, located on the anterior wall of the lower rectum. A biopsy of the rectal tumor showed the proliferation of epithelioid cells with pleomorphic features. Immunohistochemical analysis was performed. S-100 protein, CD-56, and KIT expression were positive, but HMB-45 expression was negative. Abdominopelvic computed tomography (CT) revealed multiple liver and lymph node metastases. With the diagnosis of neuroendocrine carcinoma of the rectum, abdominoperineal resection was performed. After the operation, the serum lactate dehydrogenase level had rapidly increased. An abdominal CT showed progressive liver metastases. Thirteen days after the surgery, abdominal angiography was performed, which showed multiple hypervascular tumor stains in the liver. The reservoir was implanted transcutaneously with the aid of angiography and the catheter was fixed to the proper hepatic artery. Neoadjuvant chemotherapy using cisplatin and irinotecan via the subcutaneous reservoir port was performed and a partial response was obtained. However, the final pathological diagnosis of the surgically resected specimen was malignant amelanotic melanoma of the rectum. Immunohistochemical expression differed between rectal biopsy specimens and surgically resected specimens. HMB-45 expression was positive and KIT expression was negative in the resected specimen. As preoperative pathological diagnosis showed rare rectal tumor, we measured the chemosensitivity of the rectal tumor using the collagen gel droplet-embedded culture drug sensitivity test (CD-DST) to determine the most appropriate chemotherapy regimen for the patient. However, there were no anticancer drugs tested by CD-DST for malignant melanoma. With informed consent, the patient received two cycles of immunochemotherapy consisting of dacabazine, nimustine hydrochloride, vincristine sulfate, and interferon -beta. Although the patient was treated with immunochemotherapy for metastatic liver tumor, he died because of progression of metastases.