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Journal of Crohn's and Colitis (2012) 6, 112–115

SHORT REPORT

Colorectal small cell carcinoma in ulcerative colitiswith identical rare p53 gene mutation to associatedadenocarcinoma and dysplasiaHiroyuki Hayashi a,⁎, Yohei Miyagi c, d, Akiko Sekiyama d, Sachiko Yoshida a,Sayumi Nakao b, Noriko Okamoto b, Kazutaka Koganei b, Akira Sugita b

a Department of Pathology, Yokohama Municipal Citizen's Hospital, 56 Okazawa-cho, Hodogaya-ku, Yokohama 240-8555, Japanb Department of Gastrointestinal Surgery, Yokohama Municipal Citizen's Hospital, 56 Okazawa-cho, Hodogaya-ku, Yokohama240-8555, Japanc Molecular Pathology and Genetic Division, Kanagawa Cancer Center Research Institute and Hospital, 1-1-2 Nakao, Asahi-ku,Yokohama 241-0815, Japand Laboratory for Molecular Diagnostics, Kanagawa Cancer Center Research Institute and Hospital, 1-1-2 Nakao, Asahi-ku,Yokohama 241-0815, Japan

Received 12 July 2011; received in revised form 9 August 2011; accepted 11 August 2011

Abbreviations SCC, small cell carci⁎ Corresponding author. Tel.: +81 45E-mail address: hirohayam@yahoo.

1873-9946/$ - see front matter © 2011doi:10.1016/j.crohns.2011.08.009

KEYWORDSSmall cell carcinoma;Ulcerative colitis;p53

Abstract

Colorectal small cell carcinomas (SCCs) are rare tumors and are infrequently associated with ul-cerative colitis (UC). We report a case of primary rectal SCC combined with adenocarcinomaarising 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 simulta-neously developed multiple lesions of adenocarcinoma and high-grade dysplasia in the sigmoidcolon and rectum. To elucidate whether SCC might evolve from multipotential cells in dysplasiaand/or adenocarcinoma, we examined the mutational status of TP53 and KRAS. The same clon-ality of these lesions including SCC was confirmed by the presence of an identical single nucle-otide point mutation in TP53. KRAS mutation was not observed in these lesions. Thus, theselesions seem to have developed from the same origin. Long-standing inflammation leading todysplasia might be responsible for the development of some SCCs in UC particularly when theyare combined with dysplasia and/or adenocarcinoma.© 2011 European Crohn's and Colitis Organisation. Published by Elsevier B.V. All rights reserved.

noma; UC, ulcerative colitis.331 1961; fax: +81 45 332 559co.jp (H. Hayashi).

European Crohn's and Colitis

9.

Organisation. Published by Elsevier B.V. All rights reserved.

113Small cell carcinoma in ulcerative colitis

Introduction

Primary small cell carcinoma (SCC) of the colon and rectum,either pure or mixed with another histological type, is un-common, comprising less than 1% of colorectal cancers.1,2

Most patients present with metastatic disease at the timeof diagnosis and the prognosis is particularly poor.3 Colorec-tal SCCs are frequently associated with an overlying adeno-ma or adenocarcinoma, but not associated with carcinoidtumors.4–6 According to the World Health Organization(WHO) classification, SCC is now called small cell neuroendo-crine carcinoma.5

While the most common malignancy associated with ul-cerative colitis (UC) is colorectal adenocarcinoma,7 SCC ina background of UC is very rare. We found only 11 cases ofSCC associated with UC in the English literature and noneof them have analyzed the tumors at the molecularlevel.8–16 It has yet to be established that long-standing UCmay predispose to the development of colorectal SCC.

We present a case of simultaneous SCC and adenocarcino-ma both arising in UC. By using microdissection technique,we obtained selected areas of SCC and adenocarcinoma forTP53 and KRAS mutational analysis to better elucidate thehistogenesis of SCC in a background of UC.

Case report

The patient was a 36-year-old male with 17-year history ofleft-sided UC, which was well controlled by salazosulfapyri-dine. The last colonoscopy was performed 8 years ago, how-ever he refused it since then. This time, it revealed anulcerated mass of 3 cm in diameter and a slightly elevatedmucosal lesion of 3 cm in diameter both in the rectum. His-tological examination showed adenocarcinoma in both tu-mors. Abdominal and chest computerized tomography (CT)showed no metastasis. He underwent restorative proctoco-lectomy with ileal pouch anal anastomosis.

The resected specimen revealed an ulcerated mass of4.2×4.0×1.4 cm in the rectum and widely spread irregularmucosa in the rectosigmoidal area (Fig. 1).

Histologically, high-grade dysplasia was observed in therectosigmoidal irregular mucosa, spreading 25 cm in length

Figure 1 Rectosigmoidal area of the resected specimen. Ul-cerative main tumor (x) and satellite adenocarcinomas (arrows).

from the anal verge including the ulcerated tumor and addi-tional three adenocarcinomas.

The main tumor was composed of adenocarcinoma andSCC, which is classified as mixed adenoneuroendocrine car-cinoma in the recent WHO classification (Fig. 2). The bordersof these two components were mostly clear, and SCC predo-minated. In the adenocarcinoma, large columnar cellsformed glands variable in size. The SCC part was composedof solid sheets of small cells with hyperchromatic nucleiand scant cytoplasm (Fig. 3). Immunohistochemical stainingwas positive for chromogranin A, synaptophysin (Fig. 4),and CD56 in the SCC but not in the adenocarcinoma. Thetumor invaded rectal adventitia with metastasis to multipleperirectal lymph nodes. Numerous lymphatics around thetumor were filled with SCC cells. The TNM stage waspT3pN2M0.

Three additional adenocarcinomas were found in dysplas-tic field which were barely noticed grossly, but slightlythickened areas (Fig. 1). Two of them invaded submucosawhose TNM stages were pT1pN0M0. The other was poorly dif-ferentiated and invaded muscularis propria, pT2pN0M0.

To clarify the histogenesis of the SCC, TP53 and KRASmu-tations were analyzed. Using microdissection technique, weobtained selected areas of SCC and adenocarcinoma compo-nents of the main tumor, satellite adenocarcinoma, dyspla-sia, and normal mucosa (Supplementary Fig. S1). After DNAextraction, direct nucleotide sequencing was performed.All of these 4 components harbored an identical somatic sin-gle nucleotide alteration in TP53, resulting in conversion ofthe codon 331 for glutamine in exon 9 to a stop codon(c.991CNT, p.Q331X) (Fig. 5). KRAS mutation of codon 12and 13 was not observed for any of these components.

The postoperative period was uneventful. The patientwas put on adjuvant chemotherapy regimen of cisplatin60 mg/m2 and irinotecan 60 mg/m2. There is no evidenceof recurrence 9 months after tumor resection.

Discussion

Colorectal neuroendocrine carcinoma is a rare tumor with anincidence of less than 1% of all colorectal cancers.1,2,5

Figure 2 Main tumor consists of small cell carcinoma (left)and adenocarcinoma (right) (HE stain).

Figure 3 Small cell carcinoma: solid sheet of small cells withhyperchromatic nuclei, finely granular chromatin and scant cy-toplasm (HE stain).

Figure 4 Small cell carcinoma: tumor cells are positive forsynaptophysin immunostain.

114 H. Hayashi et al.

Neuroendocrine carcinomas are subdivided into SCC andlarge cell neuroendocrine carcinoma on the basis of histo-pathological features and immunohistochemical findings.As is in our case, SCC consists of small, round to fusiformcells having minimal cytoplasm, fine granular chromatin,and small or absent nucleoli.5

While immunohistochemical staining for neuroendocrinemarkers is unnecessary to make the diagnosis of small cellcarcinoma, it is often difficult to make a distinction among

Figure 5 Electropherograms of TP53 mutation analysis: All lesionsT transition at the codon 331. Arrows indicate mutated nucleotide i

other tumors such as lymphomas.8–14 Including our case,most reported cases reacted positive to synaptophysin, chro-mogranin A, and neuron specific enolase. Neurosecretorygranules were observed by electron microscopy in somecases instead of immunohistochemistry.14–16

The most common histological type of carcinoma associat-ed with UC is adenocarcinoma.7 It has been well establishedthat long-standing inflammation predisposes to the develop-ment of colorectal adenocarcinoma. SCC might also arise inthis setting. Some authors suggested that neuroendocrine dif-ferentiation might evolve from multipotential stem cells indysplastic epithelium, because long-standing inflammationcould be responsible for the development of pancellular dys-plasia.8,12,14,15 Since most of the reported cases were not sur-gically treated, only few reports had commented the status ofsurroundingmucosa.13–15 Among them, dysplasia or adenocar-cinoma was found in adjacent mucosa in 3 cases13,14 while itwas not found in one case.15

SCCs without a background of UC are frequently observedin association with adenoma or adenocarcinoma.4–6 Vort-meyer et al. reported that poorly differentiated neuroendo-crine carcinoma and associated adenocarcinoma showed lossof heterozygosity of the same allele of APC, DCC, and TP53.6

They concluded that neuroendocrine carcinoma and associ-ated adenocarcinoma had derived from the same cell origin.In the present study, we clearly showed that SCC and sur-rounding lesions possessed an identical mutation of TP53.

One of the largest TP53 mutation databases, IARC TP53database, held by the International Agency for Research onCancer (IARC), WHO, has collected 27,580 somatic mutationsof TP53 in its latest version R15, November 2010 (http://www.iarc.fr/). In the database, the c.991CbT point muta-tion on exon 9, that generates a stop codon in place for theglutamine one, is quite rare, less than 0.1% of all mutations,and is not found in gastrointestinal tumors. The rareness ofthe TP53 mutation shown in this study strongly supportsthe idea that SCC seems to develop from multipotentialstem cells in dysplasia or adenocarcinoma. The mutual wildtype status of KRAS among the lesions further supportedtheir identical clonality.

Greenstein et al. reported eleven cases of carcinoid associ-ated with inflammatory bowel disease, which consisted of sixcases of Crohn's disease and five cases of UC.17 They concludedthat there appears to be no evidence to substantiate a directassociation between UC and histogenesis of carcinoid. The his-togenesis of carcinoid and SCC in UC might be different.

showed an identical somatic single nucleotide alteration of C ton each panel. AC, adenocarcinoma; SCC, small cell carcinoma.

115Small cell carcinoma in ulcerative colitis

Neuroendocrine carcinomas are observed in Crohn's dis-ease.14,18 Identical to our case, one of them was mixed ade-nocarcinoma and SCC of the rectum, which arose in thevicinity of high-grade dysplasia.14 The histogenesis of SCCin Crohn's disease might be the same as in UC.

The prognosis of SCC in UC has been reported to bepoor. Among the reported cases, 5 patients died withinless than 15 months, and only one patient was alive for18 months.8–12,14 In the present case, the patient under-went radical resection of the tumors and received adjuvantchemotherapy. There is no sign of recurrence for 9 months.The colorectal SCC has been reported to have sensitivity tochemotherapy akin to the pulmonary SCC.11 Thus, chemo-therapy with a combination of cisplatin and irinotecan issuggested from the literature.19

In summary, we present a case of primary rectal SCC com-bined with adenocarcinoma arising in UC. This is a first case,which showed the identical clonality of SCC, adenocarcino-ma, and dysplasia in UC. Long-standing UC may predisposeto the development of not only adenocarcinoma but alsoSCC particularly when they are combined with dysplasiaand/or adenocarcinoma.

Supplementary materials related to this article can befound online at doi:10.1016/j.crohns.2011.08.009.

Acknowledgements

There was no funding source for this study.HH, YM, and AS designed research; SN, NO, KK and AS

were the treating surgeons; HH and YS performed patholog-ical studies; YM and AS performed genetic analysis; HHdrafted the manuscript. All authors read and approved thefinal manuscript.

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