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Peritoneal sarcoidosis: the role of imaging in diagnosis.

Year: 2009
Type: article
Abstract: In 1978, Levitt and associates published an article on the use of computed tomography (CT) to diagnose neoplastic involvement of the mesentery and omentum.1 Prior to the advent of CT imaging, the radiologic diagnosis of a mesenteric or omental mass was suggested based upon displacement or secondary involvement of bowel loops on fluoroscopic barium studies such as upper gastrointestinal and small bowel series. In their early CT study, Levitt and colleagues correctly identified 18 of 27 cases with neoplastic involvement of the peritoneum. Since then, due to advances in CT technology leading to improved image quality, postprocessing techniques, and soft copy review of digital images in a stacked cine mode, the ability to noninvasively identify normal peritoneal anatomy and peritoneal disease has markedly improved.2-14 The peritoneal cavity is a potential space enclosed by the visceral and parietal peritoneum. This serosal membrane also forms the mesenteries, lines the omenta, and partially or completely covers the abdominal and pelvic viscera. The small-bowel mesentery, enclosed by folds of the peritoneum, extends diagonally from the duodenal junction in the left upper quadrant to the ileocecal valve in the right lower quadrant. This, in combination with a series of other mesenteries (transverse mesocolon, sigmoid mesentery) and ligaments (coronary, gastrohepatic, hepatoduodenal, falciform, gastrocolic, splenorenal, and phrenicocolic) formed by peritoneal reflections and attachments, leads to anatomic compartmentalization of the peritoneal cavity.7,15-17 Pathologic processes that gain access to the peritoneal cavity can disseminate throughout this space but tend to accumulate in gravity-dependent areas of stasis or arrested flow, including the peritoneal recesses of the pelvis, the right lower quadrant, the sigmoid mesocolon, and the right paracolic gutter.4-5,8,17 Most pathologic processes first affect the subperitoneal space, which lies deep to the surface lining of the visceral and parietal peritoneum, and only subsequently involves the peritoneal cavity. Contiguous extension to the retroperitoneum via the subperitoneal space can also be seen.18 Overall, CT is an excellent modality for identifying the normal anatomy of the peritoneum and detecting and characterizing peritoneal disease. Peritoneal disease is most commonly identified on CT as ascites and/or soft tissue infiltration of the peritoneal ligaments and mesenteries, typically seen first in the gravity-dependent areas described above. Although a variety of relatively common peritoneal processes can be seen, most notably peritoneal carcinomatosis related to gastrointestinal or ovarian malignancy, uncommon nonneoplastic conditions can also involve the peritoneal and subperitoneal spaces.15,16 This diverse group of nonneoplastic conditions includes systemic or multiorgan diseases such as eosinophilic gastroenteritis and amyloidosis, tumor-like conditions such as aggressive fibromatosis or inflammatory pseudotumor, and atypical infections such as tuberculosis, Whipple disease, and actinomycosis.16,17 Sarcoidosis can be categorized as both systemic and granulomatous disease and can, on rare occasions, involve the peritoneum. As described by Hackworth and colleagues,19 sarcoidosis is a relatively common systemic disorder characterized by noncaseating granuloma formation in the involved organs. Pulmonary involvement is most common and classically seen on radiologic imaging as bilateral hilar and mediastinal lymphadenopathy. This can be associated with nodular thickening along the bronchovascular bundle or more confluent nodular lung parenchymal involvement, as well as a restrictive pattern on pulmonary function tests and symptoms of cough and dyspnea. Extrathoracic manifestations of sarcoidosis are extremely variable; however, abdominal disease most commonly affects the liver, spleen, and upper abdominal/retroperitoneal lymph node chains.20 This can manifest on CT as heterogeneous hepatosplenomegaly, multiple low attenuation splenic lesions, and gastrohepatic and paraaortic lymphadenopathy. True peritoneal disease is rare,16,21-29 and ascites in the setting of sarcoidosis is most commonly secondary to associated hepatic or cardiac disease. When peritoneal disease is present, it can simulate tuberculous peritonitis or peritoneal carcinomatosis. A spectrum of findings can be identified, including simple to bloody ascites (higher attenuation, >30 HU; Figure 1) with or without infiltration, and thickening and enhancement of subperitoneal space (Figure 2). Other imaging findings of more typical hepatosplenic or pulmonary disease can help to suggest or confirm this diagnosis.16,17 Figure 1 Large-volume ascites with associated centralization of the bowel, but without obvious associated peritoneal thickening and nodularity, is seen in this patient with peritoneal sarcoidosis. Figure 2 Ascites with associated parietal peritoneal thickening and soft tissue infiltration of the mesentery and omentum is seen in a second patient with peritoneal sarcoidosis. Although in many cases of peritoneal disease the radiologic imaging findings may be nonspecific, careful correlation with clinical history may lead to the diagnosis. The patient in the case reported by Hackworth and colleagues underwent high-resolution chest CT (which included the upper abdomen) and brain magnetic resonance imaging, as well as procedures including paracentesis and liver biopsy (both of which may have been guided by ultrasound imaging). Given the positive liver biopsy and the presence of exudative ascites, it is likely that there were positive cross-sectional imaging findings in the abdomen and pelvis to suggest the possibility of peritoneal sarcoidosis in this case. Surprisingly, however, no description of abdomen and pelvis imaging is included in this patient’s extensive work-up. Although abdominal imaging may not have obviated the need for the described diagnostic procedures, it presumably directed, refined, accelerated, and facilitated the patient’s work-up and ultimate diagnosis.
Language: English
Subfield: Physiology
Field: Medicine
Open Access status: green
OpenAlex ID: W168942771
FWCI: 0.443
Cites: 26
Cited by: 8
Related to: 10