Appendix cancer CT scan

Abdominal CT scan is helpful in the diagnosis and management of appendix cancer. Findings on CT scan suggestive of appendix cancer include soft tissue thickening, wall irregularity, calcification, internal septations, preappendiceal fat stranding as well as intraperitoneal free fluid. CT scan is also one of the best imaging modalities to assess disease burden, metastatic lesions as well as disease stage.

• Experts believe that enhanced CT is the imaging modality of choice for appendix cancer.^[1]
• On CT, appendix cancer is characterized by the following findings:
  • Soft tissue thickening
  • Wall irregularity
  • Presence of pseudomyxoma peritonei
  • Calcification
  • Internal septations
  • Periappendiceal fat stranding and intraperitoneal free fluid which is a nonspecific finding
  • Cystic lesion

• Peritoneal carcinomatosis index (PCI): A widely accepted metric for assessment of disease border in appendix cancer:^[2]

• Estimated by contrast enhanced cross sectional imaging.
• Both MRI and CT scan has been used and are globally accepted imaging modalities.
• Small peritoneal seeding might be difficult to appreciate on CT.
• Sometimes it is challenging to distinguish between tumor and mucin.
• There are reports in favor of diffusion weighted MRI superiority compared to CT in evaluating extent of peritoneal involvement.^[3]

• Table and figure below demonstrate abdominal regions as well as scoring system for PCI.

• CT scan also helps in discovering distant metastatic lesions in the other organs like bone, lungs, brain and particularly liver.
• Carcinoid tumors that metastases to liver presents with carcinoid syndrome.
• Helical, contrast enhanced thriplephase CT scan is the best Ct scan method to assess liver involvement.

• Metastatic bone lesions of both adenocarcinoma and carcinoid tumors of appendix are extremely rare but might present with osteolitic (adenocarcinom) and a mixture of osteosclerotic and osteolytic changes (carcinoid tumors).^[4][5]
• Generally there is no need for imaging studies in carcinoid tumors.
• Radiographic investigation indications in carcinoid tumors are as follows:

• Tumor size > 2 cm
• Incomplete tumor resection
• Evidence of mesentric or intraabdominal involvement
• Carcinoid syndrome

• Low attenuated, well defined mass in right lower quadrant, near cecum without inflammation points to appendiceal mucocele.

• Wall thinkness does not differenciate between benign and malignant lesions.
• Intramural nodule raise suspension for cystadenocarcinoma.

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