Man, 41 years old, presents with anal pain and bleeding, characterizing hemorrhoidal
disease. His personal history shows no comorbidities or family history of colorectal
cancer. He was surgically treated for hemorrhoids, and during a screening colonoscopy,
a sessile polyp approximately 3mm in size was detected in the descending colon, where
polypectomy was performed. The pathological result showed colonic mucosa with stromal
expansion due to low-grade fusocellular proliferation, with a morphologically normal
glandular component and no malignancy. Following this, the immunohistochemistry result
diagnosed the polyp as a perineuroma, revealing focal positivity for EMA, and claudin-1,
and negativity for S-100. Perineuromas are rare benign tumors of the peripheral nerve
sheath, and through reports, they have also been identified in variants of soft tissues,
with the gastrointestinal tract being one such site. Literature on the elucidation
of the evolutionary characteristics and follow-up of patients diagnosed and treated
with perineuromas is still scarce. In the literature, using published articles as
references, a total of 157 cases of colorectal perineuromas have been reported, with
a female predominance (F:M = 1.3). Based on the reports, it is still unclear whether
symptoms such as abdominal pain, diarrhea, gastrointestinal bleeding, and a history
of previous colorectal carcinoma are related or if they are coincidental. The immunohistochemical
characteristics of colorectal perineuromas allow for their identification and differentiation
from other gastrointestinal neoplasms through specific markers. There are descriptions
of GLUT1 and claudin-1, which showed strong and diffuse immunoreactivity in 88% and
85% of cases, respectively. The expression of EMA, though present in 78% of cases,
was weak and focal. The expression of CD34 was observed in 23% of cases, but was reported
as limited and focal. Desmin and C-Kit (CD117) were negative, which aids in the differential
diagnosis with inflammatory myoglandular polyps and gastrointestinal stromal tumors,
respectively. The expression of S100 protein was reported in one case. Therefore,
it is necessary to have more reports in the literature on these rare origin benign
polyps. Like the majority of intestinal perineuromas reported in the literature, this
one appeared distal to the splenic flexure and is described as a sessile polyp.
