The Mysterious Organ. Spectrum of Focal Lesions Within the Splenic Parenchyma: Cross-Sectional Imaging With Emphasis on Magnetic Resonance Imaging  Najla Fasih, MBBS, FRCR, Ajay Gulati, MD, John Ryan, MD, FRCPC, S. Ramanathan, MD, DNB, Alampady Krishna Prasad Shanbhogue, MD, Matthew McInnes, MD, FRCPC, David B. Macdonald, MD, FRCPC, Margaret Anne Fraser-Hill, MD, FRCPC, Cynthia Walsh, MD, FRCPC, Ania Z. Kielar, MD, FRCPC, Kanchan Bhagat, MD  Canadian Association of Radiologists Journal  Volume 65, Issue 1, Pages 19-28 (February 2014) DOI: 10.1016/j.carj.2012.03.004 Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 1 (A) Splenic hemangioma in a 35-year-old man detected incidentally on ultrasound performed for unrelated indication. Sagittal ultrasound Doppler images through the left upper quadrant, revealing an echogenic lesion within the splenic parenchyma with internal vascularity. (B) Axial contrast-enhanced computed tomography (CT) image, revealing a hypoattenuating lesion within the spleen (arrow). The enhancement characteristics are difficult to discern on uniphasic CT. (C-E) Magnetic resonance imaging was performed for further characterization. The lesions are hyperintense on T2-weighted image (C), demonstrating central areas of nodular enhancement (D), with homogeneous enhancement on delayed images (E). Findings are compatible with splenic hemangiomas. Please note that the typical centripetal nodular enhancement seen in hepatic hemangiomas may not be seen. Stability in size and morphology was demonstrated on follow-up imaging. (C-E) (Arrows) represent the dominant splenic lesion in this index case, which was a hemangioma. This figure is available in colour online at http://carjonline.org/. Canadian Association of Radiologists Journal 2014 65, 19-28DOI: (10.1016/j.carj.2012.03.004) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 2 A 35-year-old patient with incidentally detected splenic hamartoma. (A) Sagittal Doppler ultrasound image, demonstrating a well-defined hypoechoic splenic mass with increased, predominantly central, vascularity. (B, C) Axial arterial phase (B) and portal venous phase (C) computed tomography images through the spleen. The lesion is hypervascular and optimally demonstrated on arterial phase only, being nearly isodense on portal venous phase (arrows). Note the contour abnormality along the medial aspect related to mass effect. (D-G) Axial T2-weighted, pre- and postgadolinium T1-weighted fat-suppressed images through the spleen. The lesion is isointense on T2-weighted (D) and T1-weighted (E), with intense enhancement on arterial phase (F) images, and it remains hyperintense to the splenic parenchyma on delayed images (G). Rarely, a central scar may be seen, as in this case (G, thick arrow). Follow-up imaging demonstrated no change in either the size or the morphology of this lesion, which confirmed its benign nature. (F) (Arrow) represents the enhancing part of the lesion. (G) (Thin arrow) represents the enhancing part of the lesion on the delayed image. This figure is available in colour online at http://carjonline.org/. Canadian Association of Radiologists Journal 2014 65, 19-28DOI: (10.1016/j.carj.2012.03.004) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 3 (A) A 27-year-old man with splenic lymphangioma. Well-circumscribed hypoechoic, lobulated mass (thin arrow) with posterior acoustic enhancement (arrowhead) in keeping with its cystic nature. Note echogenic intralocular debris (thick arrow). (B) Axial contrast-enhanced computed tomography images, demonstrating a low-attenuation lesion within the splenic parenchyma (straight arrows). Note thin internal, septae (curved arrow). (C) Axial T2 half-Fourier-acquisition single-shot turbo spin-echo (HASTE) magnetic resonance images, confirming the cystic nature. (C) (Arrows) indicate the margins of the lesion. No solid components or mural nodules can be discerned. Stability in the size and appearance was demonstrated on follow-up imaging, thereby confirming its benign nature. Canadian Association of Radiologists Journal 2014 65, 19-28DOI: (10.1016/j.carj.2012.03.004) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 4 Littoral cell angioma in a 57-year-old man who presented with anemia and thrombocytopenia. (A) Sagittal grey-scale ultrasound images, demonstrating an enlarged spleen with a craniocaudal dimension of 17 cm. The echotexture is heterogeneous, with scattered hypoechoic nodules (arrows). (B) Axial contrast-enhanced computed tomography images, demonstrating hypoattenuating lesions of variable size (arrows) within the enlarged spleen. Variable enhancement is seen on the portal venous phase. A few of these demonstrate peripheral rim calcification. (C) Hematoxylin and eosin (magnification ×20) stained section of littoral cell angioma of spleen, showing vascular spaces (thick arrow) lined by plump endothelial cells (thin arrow). This figure is available in colour online at http://carjonline.org/. Canadian Association of Radiologists Journal 2014 65, 19-28DOI: (10.1016/j.carj.2012.03.004) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 5 A 35-year-old patient with lymphoma who presented with fever and constitutional symptoms. (A) Sagittal ultrasound image, demonstrating complex, predominantly hypoechoic mass (arrow) within the spleen with scant vascularity. (B-D) The hepatic lesions appear hypointense on T1-weighted (B) and hyperintense on T2-weighted (C) sequences. Splenic lesions are isointense on both T1-weighted (B) and T2-weighted (C) sequences. (D) Delayed postcontrast images, revealing variable enhancement. Given its indeterminate nature, a biopsy was performed, which confirmed non-Hodgkin lymphoma. (B) (Arrow) represents the hepatic lesion which is hypointense on T1. Note the splenic lesion in (B) is isointense and not distinctly seen from the normal splenic parenchyma. (C, D) (Arrows) represent the hepatic and the splenic lesions. This figure is available in colour online at http://carjonline.org/. Canadian Association of Radiologists Journal 2014 65, 19-28DOI: (10.1016/j.carj.2012.03.004) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 6 Solitary splenic metastasis from malignant melanoma with spontaneous rupture and intraperitoneal hemorrhage.(A) Axial contrast-enhanced computed tomography, demonstrating solitary, inhomogeneously enhancing lesion within the spleen (thick arrow); relatively high attenuation ascites is compatible with hemoperitoneum (thin arrows). (B-D) Magnetic resonance imaging performed earlier to acute rupture. The lesion (thin arrows) reveals isointense signal on T2 and T1-weighted images with foci of cystic change and/or necrosis (thick arrows). Enhancement is heterogeneous on postcontrast images. Given its indeterminate nature on imaging, a biopsy was performed, which confirmed the lesion to be metastatic. Canadian Association of Radiologists Journal 2014 65, 19-28DOI: (10.1016/j.carj.2012.03.004) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 7 (A) Axial contrast-enhanced computed tomography images, demonstrating a heterogeneous hypervascular mass within the spleen (thin arrows), with hemoperitoneum (thick arrow). (B) Axial T2-weighted half-Fourier-acquisition single-shot turbo spin-echo (HASTE) image, demonstrating a heterogeneously hyperintense mass (thick arrow) within the spleen. (C, D) Postgadolinium dynamic contrast-enhanced images and demonstrate mural enhancement, with islands of internal hypervascularity (thin arrows). Most of the mass is necrotic secondary to previous therapeutic embolization. The lesion was biopsied, which confirmed it to be angiosarcoma. Canadian Association of Radiologists Journal 2014 65, 19-28DOI: (10.1016/j.carj.2012.03.004) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 8 A hydatid cyst in a 62-year-old woman. (A) Ultrasound performed to assess the left upper quadrant mass detected on the chest radiograph shown earlier. The lesion is of mixed echogenicity with scattered hypoechoic areas (long arrow). (B) Contrast-enhanced computed tomography, revealing mural calcifications (straight arrows) with a low-attenuation interior (curved arrow). (C-E) The calcified cyst wall is hypointense on T2-weighted images (C, thin arrow), with subtle hyperintensity on T1-weighted images (D, arrow). Internal loculations are well depicted on T2-weighted images (C, thick arrow). There is no enhancement (E, arrow) on any of the multiphasic postcontrast phases (E). Stability was demonstrated on follow-up imaging, with no change either in the size or the morphology of this lesion, which confirmed its benign nature. Canadian Association of Radiologists Journal 2014 65, 19-28DOI: (10.1016/j.carj.2012.03.004) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 9 A 45-year-old woman with known sarcoidosis. (A) Axial contrast-enhanced computed tomography image, demonstrating multiple tiny hypoattenuating lesions within the spleen (arrows). (B-E) Lesions reveal low signal intensity on T2-weighted (B) and early postcontrast fat-saturated T1-weighted arterial (C) and portal venous phase (D) dynamic magnetic resonance sequences. Homogeneous enhancement is seen on delayed images (E). This finding is sometimes seen with granulomatous lesions. Follow-up imaging demonstrated no change in either the size or the morphology of these lesions thereby confirming their benign nature. (B) (Arrows) indicate the granulomatous lesions appearing hypointense on T2. (C, D) (Arrows) show that some of these lesions which appear hypointense on the early dynamic post contrast sequences. (E) (Arrows) indicate that most of the lesions show homogeneous enhancement on the delayed image. Canadian Association of Radiologists Journal 2014 65, 19-28DOI: (10.1016/j.carj.2012.03.004) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions