title: Colorectal small cell carcinoma in ulcerative colitis with identical rare p53 gene mutation to associated adenocarcinoma and dysplasia.
abstract: Colorectal small cell carcinomas (SCCs) are rare tumors and are infrequently associated with ulcerative colitis (UC). We report a case of primary rectal SCC combined with adenocarcinoma arising in left-sided UC. Immunohistochemically, tumor cells were positive for chromogranin A, synaptophysin, and CD56 in the SCC but not in the adenocarcinoma. The patient simultaneously developed multiple lesions of adenocarcinoma and high-grade dysplasia in the sigmoid colon and rectum. To elucidate whether SCC might evolve from multipotential cells in dysplasia and/or adenocarcinoma, we examined the mutational status of TP53 and KRAS. The same clonality of these lesions including SCC was confirmed by the presence of an identical single nucleotide point mutation in TP53. KRAS mutation was not observed in these lesions. Thus, these lesions seem to have developed from the same origin. Long-standing inflammation leading to dysplasia might be responsible for the development of some SCCs in UC particularly when they are combined with dysplasia and/or adenocarcinoma.
authors.affiliation: Department of Pathology, Yokohama Municipal Citizen's Hospital, 56 Okazawa-cho, Hodogaya-ku, Yokohama 240-8555, Japan. hirohayam@yahoo.co.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Hayashi
authors.forename: Yohei
authors.initials: Y
authors.lastname: Miyagi
authors.forename: Akiko
authors.initials: A
authors.lastname: Sekiyama
authors.forename: Sachiko
authors.initials: S
authors.lastname: Yoshida
authors.forename: Sayumi
authors.initials: S
authors.lastname: Nakao
authors.forename: Noriko
authors.initials: N
authors.lastname: Okamoto
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Koganei
authors.forename: Akira
authors.initials: A
authors.lastname: Sugita
mesh_terms: D000230:Adenocarcinoma / Q000150:complications / Q000235:genetics*; D000328:Adult; D018288:Carcinoma, Small Cell / Q000150:complications / Q000235:genetics*; D003093:Colitis, Ulcerative / Q000150:complications*; D015179:Colorectal Neoplasms / Q000150:complications / Q000235:genetics*; D016158:Genes, p53; D006801:Humans; D008297:Male; D009154:Mutation; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins / Q000235:genetics*
chemical_list: C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins