Can the diagnosis on the CT scan be a false positive, and how can it be rechecked? Peritoneal Carcinomatosi

[Elvis_23]

Hi everyone.

I’ve been reading the forum and your stories for a long time, but only now decided to register and ask for advice.

English is my second language, so I apologize in advance for any mistakes in medical terms. I used ChatGPT to translate CT scans and other results.


In December, my father underwent an emergency surgery to remove a tumor in the sigmoid colon that was complicated by an abscess and peritonitis. A colostomy was performed. The histology results diagnosed:
pT2pN0, G-2, MSS/pMMR, LVI+, VI-, PNI-, Bd2, R0. ICD-O code 8140/3.
CEA after surgery was 2.34.

There was a suspicion of tumor invasion in the bladder area, but this was not confirmed at the time.

After the surgery, he developed a small ascites, which has not increased and is being managed with diuretics.

He was prescribed adjuvant chemotherapy with Xeloda (capecitabine) for 6 courses.

During chemotherapy, my father started feeling much better and gained back the 20 pounds he had lost before the surgery. His fatigue disappeared, and as he says, the difference in his condition before and after the surgery is like night and day.
His only complaint is leg swelling.
Additionally, his D-dimer is elevated.
CEA after chemotherapy was 1.4, and the rest of his blood tests are relatively normal.

However, on the follow-up CT scan a few days ago, the radiologist reported a small amount of fluid, indicating carcinomatosis and ascites.

Translator text next:

On the computer tomography scans of the abdominal cavity and pelvic cavity, a moderate amount of free fluid is detected; the fat tissue is unevenly dense and streaky, adjacent to the anterior abdominal wall, and there are interloop mesh-like hypovascular areas up to 35mm thick of a confluent nature; the peritoneal layers are dense and unevenly thickened.
CT signs of infiltrative changes in the upper parts of the bladder (may correspond to prolongatio morbi – monitoring over time), peritoneal carcinomatosis, ascites (negative dynamics), mildly expressed lymphadenopathy in the left axillary, abdominal, iliac, and right inguinal regions.)

Recommendation for follow-up monitoring and consultation with your doctor.

Our oncologist has also scheduled an MRI. But it’s quite difficult to get the answers from her.

Therefore, I hope someone who has encountered a similar case can provide some guidance:
Firstly, how was the diagnosis of carcinomatosis confirmed for you or your acquaintances? Is a CT scan alone sufficient to make such a diagnosis? What are the options for rechecking the diagnosis—PET CT, biopsy, MRI?

Has anyone experienced a false positive CT scan?

I have read almost all the topics on this forum over the past 10 years, and as I understand, there have been quite a few similar cases, but no one has particularly described how their diagnoses were confirmed and rechecked.

I would be grateful for any help and advice.

[beach sunrise]

Second opinion read of scan from a different facility is always a good idea. Compare the two.
This a a wonderful knowledgeable group here so maybe you will get some good advice.

[roarR40s]

Hi there,

My late husband was diagnosed with Peritoneal Metastasis. He had a colonoscopy that discovered a bowel obstruction. And the peritoneal Mets were confirmed during his initial surgery. The staging CT scans prior to surgery did call out extensive peritoneal Mets. In our experience CT scans were better for diagnosing Mets than PET scans. The Peritoneal mets did not light up on the Pet Scan at all. MRI is always going to be the gold standard and can be cross compared with a CT baseline. He later had HIPEC surgery in a high volume centre in Australia. In their experience, CT Scans often underestimate the PCI (peritoneal carcinomatosis index). I would get a 2nd read by a centre experienced in HIPEC surgery. If a Peritoneal Met is situated in the subcutaneous layer or abdominal wall you may be able to get it biopsied, but that does carry seeding risk. Also he may also physically feel it as a hard immovable lump in the abdomen wall.

Good luck!