Intrapancreatic accessory spleen: CT appearance and differential diagnosis

The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Hospital, JHOC 3235A, 601 North Caroline Street, Baltimore, MD, 21287, USA, .
Abdominal Imaging (Impact Factor: 1.63). 12/2011; 37(5):812-27. DOI: 10.1007/s00261-011-9830-x
Source: PubMed


Although autopsy studies report that the second most common site of the accessory spleen is in the tail of the pancreas, intrapancreatic accessory spleens (IPASs) are rarely recognized radiologically. With recent improvements in imaging techniques, IPASs are more commonly detected on imaging studies. IPAS can be mistaken for other type of mass-forming lesions in the tail of the pancreas, particularly an asymptomatic small neuroendocrine neoplasm. Rarely, an epidermoid cyst originating from IPAS may simulate other cystic pancreatic lesion. Accurate preoperative diagnosis would obviate unnecessary surgery. IPAS should be considered when a hypervascular mass is seen in the tail of the pancreas on CT. Typical location, similar attenuation of the lesion to the spleen on noncontrast, and postcontrast CT at different phases are helpful to make diagnosis of IPAS. In particular, characteristic heterogeneous contrast enhancement of IPAS on the arterial phase may be helpful for correct diagnosis. However, when it remains difficult to exclude the other diagnosis, (99m)Tc labeled heat-damaged red blood cell scintigraphy or superparamagnetic iron oxide-enhanced MRI can be used to confirm the diagnosis of IPAS.

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    Radiology Case Reports 01/2013; 8(1). DOI:10.2484/rcr.v8i1.802
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    ABSTRACT: Image findings of intrapancreatic accessory spleen (IPAS) can closely resemble those of neuroendocrine tumor (NET) of the pancreas. To investigate the usefulness of diffusion-weighted imaging (DWI) for differentiating IPAS from small (≤3 cm) hypervascular NET of the pancreas. The visually assessed signal intensity of pancreatic lesions compared with the spleen on DWI (b value of 1000 s/mm(2)) and the apparent diffusion coefficient (ADC) values were compared in 25 patients with IPAS and 31 patients with small hypervascular NET. Two blinded radiologists independently rated their confidence in differentiating the two conditions and compared the diagnostic performance of contrast-enhanced magnetic resonance imaging (CE-MRI) alone with that of combined CE-MRI and DWI. The isointensity of the pancreatic lesions compared with the spleen on DWI was more frequently observed in IPAS than in NET (92% vs. 12.9%, P < 0.001). The mean ADC value was significantly lower in IPAS than in NET (0.90 × 10(-3) mm(2)/s vs. 1.44 × 10(-3) mm(2)/s, P < 0.001). The sensitivity and specificity of ADC quantification for differentiating the two conditions when using 1.07 × 10(-3) mm(2)/s as the cut-off value were 96% and 93.5%, respectively. For both readers, the area under the receiver operating characteristic curve and accuracy in differentiating the two conditions of combined CE-MRI and DWI were significantly greater than those of CE-MRI alone (P ≤ 0.039). Visual assessment of DWI and ADC quantification were useful in differentiating IPAS from small hypervascular NET of the pancreas.
    Acta Radiologica 11/2013; 55(10). DOI:10.1177/0284185113513760 · 1.60 Impact Factor
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    ABSTRACT: Objective: The aim of this study was to evaluate the ability of computed tomography (CT) in differentiating between intrapancreatic accessory spleen (IPAS) from pancreatic neuroendocrine tumor (PanNET). Methods: Eight IPASs and 12 PanNETs in the pancreatic tail were retrospectively evaluated by 2 radiologists. Readers assigned a diagnosis to each examination and evaluated for the presence or absence of 9 CT findings that may aid in the diagnosis. Results: Reader 1 had a sensitivity of 0.83 and a specificity of 1; reader 2 had a sensitivity of 0.78 and a specificity of 0.86. Three of the 9 CT findings were found to be statistically significant in IPASs: the lesion present along the pancreatic dorsal surface, the lesion demonstrating the same enhancement as the spleen on venous phase, and heterogeneous enhancement during arterial phase. Conclusions: CT can be used to differentiate between IPAS and PanNET with good specificity and sensitivity. The IPAS mirrors the spleen's enhancement and is usually located along the dorsal surface of the pancreas.
    Journal of computer assisted tomography 06/2014; 38(6). DOI:10.1097/RCT.0000000000000127 · 1.41 Impact Factor
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