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Abdomen » Gastrointestinal
Appendiceal cancer and associated pseudomyxoma peritonei
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This 55yo male presented as an out-patient for an ascitic tap, based on recent CT findings from another institution. The patient was asymptomatic and appeared generally well. No images were available at the time for comparison. On palpation of the abdomen an irregular shaped and non-compressible mass is felt over random areas. The patients stated that he had been attending his GP frequently for on-going change in bowel habits, which has been tentatively diagnosed as Irritable Bowel Syndrome. The patient mentioned the recent CT and that he has a colonoscopy booked for the following day.

Caption: Sagittal through left lobe of liver
Description: This image demonstrates the heterogeneous mass/caking occupying the anterior intraperitoneal region and displacing the liver posteriorly
Caption: Sagittal RUQ
Description: This sagittal image of the right upper quadrant demonstrates the gel-like ascites within Morison's pouch.
Caption: Sagittal image of the GB
Description: The gallbladder is thin walled.
Caption: Sagittal, Right Iliac Fossa
Description: Swollen "appendix-like" structure surrounded by a complex mass
Caption: Transverse through one of the palpable abdominal masses
Description: Caked intraperitoneal mass, almost sponge like in appearance.
Caption: Transverse CT through liver and spleen
Caption: Coronal CT
Description: Coronal CT of the dilated appendix with suspected perforation
Caption: CT abdomen, coronal plane
Differential Diagnosis Pseudomyxoma peritonei caused by mucinous ovarian, appendiceal or other gastrointestinal tumor
peritoneal carcinomatosis (metastasis) without mucinous ascites
peritoneal sarcomatosis
peritoneal mesothelioma
tuberculous peritonitis
Final Diagnosis
Pseudomyxoma Peritonei due to ruptured malignant mucocele of the appendix
The ultrasound demonstrates multiple hypoechoic masses containing scattered stationary high-amplitude echogenic foci.  The masses are complex, non-compressible and some present a honeycomb appearance.  The masses appear to be compressing adjacent organs. 
A few interspersed anechoic areas in the right upper quadrant / Morrisson's pouch have a ‘solid’ appearance (void of respiratory movement between the liver & the right kidney) 
A small pocket of ascites fluid containing some sediment is seen in the left iliac fossa.
The gallbladder wall is noted to be thin.
A non-compressible and blind-ended tubular structure is seen in the right iliac fossa, consistent with a very dilated appendix. The patient confirmed he had no history of an appendectomy. 
The ascitic tap was not performed.

CT report:
Diffuse nodular low attenuation mesenteric and peritoneal fluid throughout the abdomen causing scalloping of the liver and mass effect on the bowel. A massively fluid filled dilated appendix measuring 2.4 cm in diameter, with a possible defect in the wall of the appendix. No mural thickening of the appendix.

Pseudomyxoma peritonei:
"The term pseudomyxoma peritonei is a clinical or radiologic description rather than a pathologic diagnosis. Pseudomyxoma peritonei (or jelly belly) describes the finding of copious, thick mucinous or gelatinous material on the surfaces of the peritoneal cavity".1

“The most common cause of Pseudomyxoma peritonei is a ruptured mutinous tumor of the appendix/appendiceal mucocele”.2

Typical ultrasound findings in pseudomyxoma peritonei are: 
Hypoechoic spaces within the abdomen which contain dense punctuate echoes or floccules which seldom or never move with the change of body position. 
Honeycomb-like septae within the hypoechoic spaces.
Notches or scalloping of the surface of liver or spleen due to the mucinous material and/or the mucinous lesions. 3

Case References
1. Secondary Tumors and Tumorlike Lesions of the Peritoneal Cavity: Imaging Features with Pathologic Correlation
Angela D. Levy, Janet C. Shaw, and Leslie H. Sobin. RadioGraphics 2009 29:2, 347-373

2. Takeuchi M, Matsuzaki K, Yoshida S et-al. Imaging findings of urachal mucinous cystadenocarcinoma associated with pseudomyxoma peritonei. Acta Radiol. 2004;45 (3): 348-50.

3. Zhongguo Yi Xue Ke Xue Yuan Xue Bao. Ultrasonographic Features of Pseudomyxoma Peritonei and TheirComparison with Computed Tomographic Findings. 2015 Aug;37(4):424-9. doi: 10.3881/j.issn.1000-503X.2015.04.010.

4. Gupta S, Singh G, Gupta A, et al. Pseudomyxoma peritonei: An uncommon tumor. Indian Journal of Medical and Paediatric Oncology : Official Journal of Indian Society of Medical & Paediatric Oncology. 2010;31(2):58-61. doi:10.4103/0971-5851.71657.;year=2010;volume=31;issue=2;spage=58;epage=61;aulast=Gupta

Technical Details Toshiba Aplio 500 with curved and Linear array transducers. Both with colour Doppler ability. Scanned with light transducer pressure to avoid compressing the small pocket of ascites. Scanned over the palpable ROI’s
Follow Up The patient had a laparoscopy. The tubular structure was confirmed as a diseased appendix and cytology confirmed pseudomyxoma peritonei from cancer of the appendix.
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