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\begin{document}

\title{Rectal metastasis of sigmoid colon cancer}



\author[1]{TAKAYUKI YAMADA}%
\affil[1]{Asunaro Clinic}%


\vspace{-1em}



  
  \date{May 24, 2024}


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\selectlanguage{english}
\begin{abstract}
A 73-year-old man underwent a stage II sigmoid colon cancer resection.
Careful monitoring was undertaken, and no evidence of metastasis or
anastomotic recurrence was noted until 51 months later. Anal examination
revealed a pink, firm perianal tumor histologically identified as a
metastasis of the colon adenocarcinoma.%
\end{abstract}%



\sloppy


\textbf{Introduction}

Sigmoid colon cancer sporadically metastasizes to regional lymph nodes,
liver, and lungs. However, intestinal metastasis of colon cancer rarely
occurs. The diagnosis of rectal metastasis of sigmoid colon cancer was
not initially suspected in this case. Still, it was indeed identified,
despite 51 months of careful postoperative monitoring for surgical site
recurrence and distant metastasis that failed to reveal this metastasis.

\textbf{Case History/Examination}

A 73-year-old man underwent sigmoidectomy with lymph node dissection for
stage II sigmoid colon cancer 4 years ago. Afterward, he was carefully
monitored using chest- and abdominal computed tomography (CT), serum
tumor markers, and colonoscopies. No evidence of metastasis or
anastomotic recurrence was observed until 4 years and 3 months
postoperatively when he experienced anal bleeding during defecation,
initially felt to be caused by internal hemorrhoids. Anal examination
revealed a pink, firm perianal tumor (Figure A). On biopsy, the sample
showed heterotypic columnar epithelium arranged in irregular duct-like,
amalgamation duct-like, and comb-like configurations under stratified
squamous epithelium, indicating that the tumor was a metastasis of the
colonic adenocarcinoma (Figure B). The patient was oxygen-dependent due
to pulmonary fibrosis and emphysema, and had a history of rheumatoid
arthritis and variant angina, which contraindicated rectal amputation.

\textbf{Differential diagnosis, investigations, and treatment}

A positron emission tomography (PET) scan revealed an inoperable left
inguinal lymph node metastasis. PET-CT did not detect any abnormal
accumulation in his lungs, pancreas, or gallbladder. Upper
gastrointestinal endoscopic examination was unremarkable. A presumptive
diagnosis of rectal metastasis of sigmoid colon cancer was made.

\textbf{Outcome and follow-up}

Since the patient's performance status precluded surgical intervention,
he received chemoradiotherapy for local control of the bleeding tumor.
The bleeding has been well contolled and he is surviving with the
disease.

\textbf{Discussion}

In general, postoperative detection of recurrent alimentary canal
cancers is monitored using chest-abdominal-pelvic CTs, assessing for
distant metastasis (lungs, liver, adrenal glands, bones, or spleen) or
dissemination (ascites, pleural effusion, paraaortic or regional
lymphadenopathy) yearly for 4 years. Unfortunately, conventional CT
cannot detect lymph node metastasis \textless{}10 mm in size, and no
objective radiologic criteria for lymph node metastasis
exist.\textsuperscript{1} Additionally, CT scans find it difficult to
detect pinpoint nodular, circumintestinal involvement. Furthermore,
intestinal metastasis rarely occurs.\textsuperscript{2} The exact
mechanism of colorectal metastasis from primary colorectal cancer has
not been fully elucidated. Intestinal metastases are derived from
submucosal vessels and typically present as submucosal tumors because
the cancers are mainly located in the submucosa and the muscularis
propria. Direct incisional biopsy was able to be performed in this case;
if manual incisional biopsy had been unfeasible because of tumor
location, endoscopic ultrasound fine-needle aspiration or boring biopsy
would have been chosen.\textsuperscript{3} These procedures require a
specialized institution. Conventional follow-up colonoscopy examinations
have difficulty detecting this type of recurrence. Anastomotic
recurrence occurs occasionally but this was not the case for this
patient. Sigmoid colon cancer lymph node metastases arise from the
paracolic lymph nodes to the inferior mesenteric lymph nodes and
paraaortic lymph nodes, rarely metastasizing to the pararectal lymph
nodes. This suggests that this was a blood-borne metastasis.

Given the limitations of his performance status, he received only
chemoradiotherapy for local control of the bleeding tumor. Therefore,
this case was a presumptive diagnosis of rectal metastasis of sigmoid
colon cancer.

Rectal metastasis of colon cancer rarely occurs. Therefore, this report
can help clinicians to identify this rare metastasis.

\textbf{Author Contributions:}

Takayuki Yamada: first author and diagnostician.

\textbf{References}

1. Hong EK, Landolfi F, Castagnoli F, et al. CT for lymph node staging
of Colon cancer: not only size but also location and number of lymph
node count. \emph{Abdom Radiol (NY)}. 2021 September;46(9):4096-4105.
doi:\emph{10.1007/s00261-021-03057-0}. 2. Kojima S, Sakamoto T, Nagai Y,
Honda M, Ogawa F. Metachronous rectal metastasis from primary transverse
colon cancer: a case report.\emph{Surg Case Rep}. 2018 August 9;4(1):90.
doi:\emph{10.1186/s40792-018-0498-0}. 3. Yamane H, Ishida M, Banzai S,
et al. Advanced gastric cancer with features of a submucosal tumor
diagnosed by endoscopic ultrasound-guided fine needle aspiration and
boring biopsy preoperatively: A case report and literature review.
\emph{Int J Surg Case Rep}. 2019 February 8;55:223-226.
doi:\emph{10.1016/j.ijscr.2019.01.044}.

\textbf{Figure legends}

Figure A: An anal examination revealing a pink, firm perianal tumor.

Figure B: The biopsy sample showing heterotypic columnar epithelium
arranged in irregular duct-like configurations, amalgamation duct-like
configurations, and comb-like configurations under stratified squamous
epithelium.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Figure-A/Figure-A}

\end{center}
\end{figure}\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Figure-B/Figure-B}

\end{center}
\end{figure}

\selectlanguage{english}
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\end{document}

