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Journal of Cancer Research and Therapeutics, Vol. 7, No. 2, April-June, 2011, pp. 231-233 Letter to the Editor FDG avid "abdominal band" representing omental cake in mucinous adenocarcinoma of the appendix: Potential implications for disease monitoring with FDG-PET in this setting Sandip Basu1, Tanuja Shet2 1 Radiation Medicine Centre, Bhabha Atomic Research Centre, Tata Memorial Hospital Annexe, Mumbai, Maharashtra, India Code Number: cr11061 PMID: 21768727 Sir, We herein report a case of a 61-year-old male who was diagnosed recently with moderately differentiated mucin-secreting adenocarcinoma of the appendix. On colonoscopy, it appeared as an ulcerated friable appendicular mass from which multiple biopsies were taken that was suggestive of this diagnosis [Figure - 1]. He had undergone Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) imaging with this referral diagnosis for a whole body disease survey. The whole body FDG-PET demonstrated an unusual broad and prominent FDG avid abdominal band. Also, there were certain discrete foci, which suggest peritoneal seeding by the disease and irregular FDG uptake superior and lateral surface of the liver [Figure - 2]. The contrast-enhanced CT scan of the abdomen (undertaken in a different diagnostic center subsequently) reported diffuse thickening, stranding, and nodularity of the omentum forming an "omental cake" and also there was evidence of subcapsular hepatic deposits. The peritoneal biopsy proved this to be due to metastatic deposits of well-differentiated mucin-secreting adenocarcinoma consistent with the primary from the appendix [Figure - 3]a and b. Diffuse peritoneal infiltration (omental cake) occurs most commonly as secondary to intraperitoneal tumor spread. Other less common causes of the peritoneal infiltration include inflammatory conditions, such as tuberculosis, Crohn′s disease, phlegmonous pancreatitis, granulomatous enterocolitis, and others. However, it most commonly results in ovarian or gastrointestinal cancer. The diagnosis has to be interpreted in a given clinical setting and the patient history and diagnosis. [1],[2] In our cursory experience, the peritoneal involvement by tuberculosis is usually characterized by a relatively low-grade diffuse uptake all over the abdomen, giving an appearance of enhanced background. We believe, however, a standardized uptake value (SUV) cutoff cannot be taken as confirmatory of a diagnosis, and the gold standard for diagnosis continues to be biopsy. The discussion of more cases like this will significantly help in developing an evidence base for noninvasive diagnosis with PET and will enhance its role and reliability in this setting. The message and the learning points in the presented case are the following: (a) Recognizing the pattern of tracer uptake is of critical importance in the interpretation of PET imaging. The present case illustrates a very striking uptake pattern in the setting of peritoneal carcinomatosis. (b) The present case is interesting due to the fact that it depicts the role of FDG-PET in peritoneal metastatic deposits of well-differentiated mucin-secreting adenocarcinoma of the appendix, which is contrary to the common belief that it has a limited role in the evaluation of mucinous tumors, particularly in hypocellular lesions with abundant mucin. It has been reported that the sensitivity of FDG-PET imaging for the detection of mucinous carcinoma is significantly lower than in nonmucinous carcinoma. However, it should be remembered that the FDG uptake in a tumor is influenced by multiple factors, such as mitotic activity, tumor grade, Ki 67 index, and overall tumor biology. In a particular tumor type, high grades can be encountered that would predict aggressive biology and FDG uptake can be a surrogate biomarker for this. The present observation also raises the potential of this modality in these variants for noninvasive disease characterization and monitoring and image-guided biopsy in this setting. References
Copyright 2011 - Journal of Cancer Research and Therapeutics The following images related to this document are available:Photo images[cr11061f3.jpg] [cr11061f2.jpg] [cr11061f1.jpg] |
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