6. Rectal adenocarcinoma

Staining: HE

Overview. Because there is a large ulceration in the tumor do we know that the cancer is of ulcerative type.

Organ: Rectum

Description:

On the leftmost part of the slide is the tissue normal and healthy.

In the middle of the tumor can we see a large ulceration. The tumor invades beyond the subserosal fat tissue. The tumor cells only show mild pleiomorphism and they do form tubular structures. The neostroma is hypercellular.

In the upper right corner of the slide can we see some lymphovascular invasion.

Diagnosis: Rectal adenocarcinoma T3

Hypercellular neostroma and tubular structures

Risk factors:

• Inflammatory bowel disease
• Adenomatous polyps
• Western diet
• Smoking, alcohol

Theory:

This tumor invades beyond the muscle and even the subserosa, which gives it the staging T3. The tumor cells only show mild pleiomorphism and they produce abnormal tubular/glandular structures, indicating that the tumor is well-differentiated and therefore low-grade.

Some of the tubular structures contain dirty necrosis. The tumor is of ulcerative type as we can see a large ulceration in the tumor. The neostroma is hypercellular.

Muscularis propria invasion

Colorectal cancer is commonly associated with mutations in the APC gene or with microsatellite instability.

The lymphovascular invasion may in fact be a metastatic lymph node and not a vessel, however we see no lymphoid tissue so a lymphovascular invasion is more likely.

The tumor invades beyond the subserosal fat

The tumor cells (those that comprise the tubular structures) show only a mild pleiomorphism.

The lymphovascular invasion. This used to be a vessel, either a lymphatic or vascular one, that is now filled with tumor cells (and dirty necrosis!).