Rieko Yamada

A Case of Benign Schwannoma of the Transverse Colon with Granulation Tissue

Schwannomas occurring in the gastrointestinal tract are rare, and among them, schwannomas of the large intestine are extremely rare. In this paper, we report a case of a macroscopically atypical schwannoma of the transverse colon. The case is a female aged 67. Stool occult blood test was positive, and colonoscopy revealed a protruded lesion resembling a type 1 carcinoma measuring 4 cm with a reddish and uneven surface on the transverse colon. The surface was smooth and lobulated in observation with indigo carmine spray, and granulation tissue was revealed by biopsies. CT of the abdomen showed an irregular mass, and clinical examinations could not rule out malignancy. Therefore, partial transverse colectomy with peripheral lymph node dissection was performed. Histologically, proliferation of spindle cells was observed originating from the muscularis propria, and most of the upper part of the lesion was replaced by granulation tissue. In immunohistochemical staining, S-100 protein and NSE were positive while KIT, CD34, desmin and smooth muscle actin were negative, and the tumor was therefore diagnosed to be a schwannoma. In addition, since the MIB-1 labeling index was low and virtually no mitosis was observed, it was diagnosed as benign tumor.

Accuracy of CT Colonography for Detection of Polypoid and Nonpolypoid Neoplasia by Gastroenterologists and Radiologists: A Nationwide Multicenter Study in Japan.

OBJECTIVES:The objective of this study was to assess prospectively the diagnostic accuracy of computer-assisted computed tomographic colonography (CTC) in the detection of polypoid (pedunculated or sessile) and nonpolypoid neoplasms and compare the accuracy between gastroenterologists and radiologists.METHODS:This nationwide multicenter prospective controlled trial recruited 1,257 participants with average or high risk of colorectal cancer at 14 Japanese institutions. Participants had CTC and colonoscopy on the same day. CTC images were interpreted independently by trained gastroenterologists and radiologists. The main outcome was the accuracy of CTC in the detection of neoplasms ≥6 mm in diameter, with colonoscopy results as the reference standard. Detection sensitivities of polypoid vs. nonpolypoid lesions were also evaluated.RESULTS:Of the 1,257 participants, 1,177 were included in the final analysis: 42 (3.6%) were at average risk of colorectal cancer, 456 (38.7%) were at elevated risk, and 679 (57.7%) had recent positive immunochemical fecal occult blood tests. The overall per-participant sensitivity, specificity, and positive and negative predictive values for neoplasms ≥6 mm in diameter were 0.90, 0.93, 0.83, and 0.96, respectively, among gastroenterologists and 0.86, 0.90, 0.76, and 0.95 among radiologists (P<0.05 for gastroenterologists vs. radiologists). The sensitivity and specificity for neoplasms ≥10 mm in diameter were 0.93 and 0.99 among gastroenterologists and 0.91 and 0.98 among radiologists (not significant for gastroenterologists vs. radiologists). The CTC interpretation time by radiologists was shorter than that by gastroenterologists (9.97 vs. 15.8 min, P<0.05). Sensitivities for pedunculated and sessile lesions exceeded those for flat elevated lesions ≥10 mm in diameter in both groups (gastroenterologists 0.95, 0.92, and 0.68; radiologists: 0.94, 0.87, and 0.61; P<0.05 for polypoid vs. nonpolypoid), although not significant (P>0.05) for gastroenterologists vs. radiologists.CONCLUSIONS:CTC interpretation by gastroenterologists and radiologists was accurate for detection of polypoid neoplasms, but less so for nonpolypoid neoplasms. Gastroenterologists had a higher accuracy in the detection of neoplasms ≥6 mm than did radiologists, although their interpretation time was longer than that of radiologists.

Endoscopic Diagnosis and Treatment for Colorectal Cancer

Colonoscopy plays an important role in the medical care of patients with colorectal cancer. It is generally used for both the diagnosis of different stages of colorectal cancer and the treatment of early colorectal cancer and its precursors. The recent progress in colonoscopy has been remarkable. Endoscopes with variable rigidity and small diameters provide efficient insertion to the cecum and result in lower distress for patients. Trained colonoscopists can insert endoscopes into the cecum within a few minutes, and it is not necessary to anesthetize patients without severe peritoneal adhesion. We can obtain good-quality pictures and special images to assist in diagnosis by using highvision endoscopes, magnifying endoscopes, dye spray, and narrow-band imaging (NBI). Determining whether a colorectal carcinoma can be curatively resected by endoscopic treatment or whether the carcinoma has a risk of lymph node metastasis is a very delicate and important task. In particular, the depth of cancer invasion is related to lymph node metastasis; therefore, endoscopic ultrasonography and the classification of pit patterns, capillary patterns via NBI, and the lesion-lifted condition are used to diagnose the depth of cancer invasion (Kato, 2001, Sano, 2008). Treatment for colorectal neoplastic lesions begins with hot biopsy and snare polypectomy, and recently, endoscopic submucosal resection (EMR), piecemeal EMR (EPMR), and endoscopic submucosal dissection (ESD) have become available for large and flat lesions of the colon and rectum. Early colorectal carcinoma is defined as a carcinoma within the submucosal layer that is not invading the muscularis propria. Carcinoma in situ (mucosal carcinoma) and carcinoma that slightly invades the submucosa and without risk factors for metastasis do not metastasize into lymph nodes or distant organs. Nonmetastatic carcinoma is cured by local resection with colonoscope. It is important to make an accurate diagnosis by endoscopy and to perform confident resection for pathological evaluation. In this chapter, we describe endoscopic diagnosis for colorectal carcinoma and differential diagnosis, and treatment options for early colorectal cancer without metastasis and for adenoma which is regarded as a precancerous condition. In addition, we briefly discuss risk factors for lymph node metastasis in early colorectal carcinoma.