PMC9149479_01
Moderately differentiated adenocarcinoma with a decrease in nuclear polarity and irregular tubule formation (red arrow) in addition to necrosis (yellow arrow).
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F1
An urgent colonoscopy revealed a circumferential mass in the rectum, with biopsy confirming a moderately differentiated adenocarcinoma consistent with a rectal primary tumor (shown in Fig. 1).
MRI of the pelvis demonstrates a rectal tumor with an inferior margin of 3.5 cm superior to the anal verge (red arrow). A presacral nodule extending to approximately 1 mm from the mesorectal fascia posteriorly is seen (yellow arrow).
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F2
Subsequent MRI of the abdomen and pelvis demonstrated a large rectal tumor with an inferior margin of 3.5 cm superior to the anal verge (shown in Fig. 2), and multiple perirectal and presacral nodules.
PMC9149479_02
Poorly differentiated adenocarcinoma with signet ring cells (red arrow).
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F3
The pathology report confirmed a poorly differentiated adenocarcinoma with signet ring cells (shown in Fig. 3).
MRI of the pelvis demonstrates a rectal mass spanning a length of 9 cm and located approximately 1 cm above the anorectal junction (red arrow). There are 7-8 enlarged lymph nodes adjacent to the mass in the mid rectum in the presacral space highly suspicious for nodal metastasis (yellow arrows).
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F4
A pelvic MRI showed several enlarged lymph nodes adjacent to the tumor (shown in Fig. 4), suspicious for nodal metastasis.