Case description
A 33-year-old man was taken for counseling after discovering genetic
mutations. Firstly, on March 21st, 2022, the patient went to Anhui
Provincial Hospital for treatment with chief complaint of hematochezia
for several months. He then underwent a colonoscopy which was showed
that a 3.5 cm long pedunculated polyp could be seen in the descending
colon at a distance of 55 cm from the edge of the anus. And then a 0.8
cm size polyp was detected near to it. In addition, another larger
polyp, about 6 cm in size, was found at the junction of the sigmoid and
descending colon. It was worth noting that this distinct sessile polyp
with a lobulated surface and varicose veins of the surrounding mucosa
almost blocked the intestinal lumen. Several polyps ranging in size from
0.5 cm to 1 cm also were found in the rest of the colon. Pathologic
findings after biopsy confirmed that the maximal polyp is a
tubulovillous adenoma with moderate dysplasia. A computed tomography of
the abdomen, performed half a month later, documented multiple lesions
in the splenic flexion of the colon and in the sigmoid, considering the
larger one, which is local with intussusception proximal to the sigmoid.
Genetic analysis revealed a deleterious single allele heterozygous
germline mutation. MUTYH gene sequence analysis confirmed the following
heterozygous mutation: c.55CT (p.R19X) in exon 2 (ClinVar
NM_001128425). In addition, the LHX4 mutation: c.256G>A
(p.G86S) in exon 3 (ClinVar NM_033343) also was notable. The
electrophoretic sequence of MUTYH exon 2 revealing mutations is shown in
Figure 2. This genetic analysis confirmed that the MUTYH mutation was a
single allele heterozygous mutation. A diagnosis of MAP was then
confirmed. His mother and daughter have the same MUTYH gene mutation,
however, while no particular genetic variations occurred in his father.
Interestingly, this MUTYH mutation carrier had a family history
consistent with dominant inheritance. When he was admitted to another
Class A tertiary hospital on May 2nd, 2022, he underwent endoscopic
mucosal resection surgery. Pathological analysis showed that cystic
fibrosis located 25 cm from the margin of anus was a microvillous
tubular adenoma with high grade intraepithelial neoplasia and local
carcinogenesis. Specifically, cancerous tissue at the site has
infiltrated into the 3mm submucosal layer, but the vertical and lateral
margins were both negative. The surgeon recommended abdominal surgery
for the patient, but failed. Almost about 22 days later, the patient
sought further endoscopic treatment and came to our hospital. An
abdominal enhancement CT was later performed, documenting multiple mass
lesions of the colonic splenic curvature and sigmoid colon. The next day
the patient underwent colorectal EMR and ESD (Figure 3). Lesions between
5 mm and 6 cm are found during surgery. The largest tissue sample with
dissociative tissue pieces was a villous tubular adenoma consisting of
large low-grade and rarely high-grade intraepithelial neoplasia. In
addition, a lesion grows nearby, the pathology of which was a villous
tubular adenoma with low-grade intraepithelial neoplasia. The splenic
flexure and sigmoid also have several similar polyps. Some hyperplastic
polyps were detected in the rectum. All pathologically confirmed lesion
strains were negative. Immunohistochemistry analysis was added showing
that the junction of the descending colon with the sigmoid, sigmoid and
splenic flexure showed similar results: all polyps were sent for
investigation manifested as Desmin (mucosal muscle +), CEA (+), P53 (+),
including wild-type and partially mutant and various grades of Ki67(+).
Three months ago, he came to our hospital for colonoscopy surveillance.
And the positron emission tomography (PET-CT) scan was unremarkably
normal. When he was hospitalized this time, his bowel preparation was
not fairly satisfactory as a large amount of feces remained in the
bowel(Figure 4). Many polyps were found again after the colonoscopy.
Tubular adenomas and hyperplastic polyps were removed with the technique
of a cold snare. Considering the poor bowel preparation, he was
instructed to repeat the colonoscopy after 3 months. At present, he went
to our hospital again for a colonoscopy. During this process, several
newly emerged polyps were found in the colon and were removed via
conventional EMR. These polyps remain concentrated in the distal colon,
including the descending colon, sigmoid colon, and rectum(Figure 5). In
order to avoid unnecessary risks, we also arranged an additional CT
examination for him, and this time there were no signs of
intussusception and other potential malignant changes.