Everything you need to know about Computed Tomography (CT)
Spleen         Share on Facebook

Accessory Spleen and Splenules

  • "Splenosis is the benign acquired condition of heterotopic autotransplantation of splenic tissue in another anatomic compartment of the body after splenic rupture, usually either traumatic or iatrogenic. It is often found incidentally, but rarely it can present symptomatically. Splenosis most frequently occurs in the abdominal and pelvic cavities, but it has also been described in numerous other locations throughout the body. Radiographically, splenosis can mimic various pathologic entities, including primary malignancy or metastatic disease."
    CT of Splenosis: Patterns and Pitfalls
    Spencer T. Lake, Pamela T. Johnson, Satomi Kawamoto, Ralph H. Hruban, Elliot K. Fishman
     AJR 2012; 199:W686-W693
  • "The splenic tissue present in splenosis is active, as evidenced by the absence of Howell-Jolly bodies, Heinz bodies, and other erythrocyte abnormalities in the peripheral smears of many asplenic patients with splenosis. Therefore, nuclear scintigraphy using heat- damaged RBCs tagged with technetium-99 is currently the diagnostic tool of choice because of the high uptake of damaged erythrocytes by this ectopic splenic tissue."
    CT of Splenosis: Patterns and Pitfalls
    Spencer T. Lake, Pamela T. Johnson, Satomi Kawamoto, Ralph H. Hruban, Elliot K. Fishman
     AJR 2012; 199:W686-W693
  • "In 25% of thoracic splenosis cases, chest CT shows a solitary pleura-based nodule, and multiple nodules are seen in the remaining 75% of cases. Nodule attenuation reflects that of normal splenic tissue. The splenic implants can easily be confused with other processes including primary or metastatic tumor or infection particularly if the abdomen is not imaged to disclose the absence of the spleen."
    CT of Splenosis: Patterns and Pitfalls
    Spencer T. Lake, Pamela T. Johnson, Satomi Kawamoto, Ralph H. Hruban, Elliot K. Fishman
     AJR 2012; 199:W686-W693
  • "Splenosis in the abdominal or pelvic cavity is thought to occur in as many as 65% of cases of splenic rupture. The most frequent locations include the greater omentum , small-bowel serosa, parietal peritoneum, and undersurface of the diaphragm .Once splenosis implants have been identified, careful evaluation may disclose additional implants throughout the peritoneum; the implants can be widespread."
    CT of Splenosis: Patterns and Pitfalls
    Spencer T. Lake, Pamela T. Johnson, Satomi Kawamoto, Ralph H. Hruban, Elliot K. Fishman
     AJR 2012; 199:W686-W693
  • " The average time between the inciting trauma and abdominal or pelvic splenosis is 10 years, although splenosis has been found to occur in as few as 5 months after trauma. Although abdominal splenosis is frequently asymptomatic, it can present with hemorrhage, pain secondary to infarction or torsion, or obstruction of the intestinal or urinary tract."
    CT of Splenosis: Patterns and Pitfalls
    Spencer T. Lake, Pamela T. Johnson, Satomi Kawamoto, Ralph H. Hruban, Elliot K. Fishman
     AJR 2012; 199:W686-W693
  • "Splenic nodules in the pancreas can represent either intrapancreatic accessory spleen or splenosis, the latter of which is rare. These entities must be differentiated from pancreatic malignancy-specifically, pancreatic neuroendocrine (islet) tumor or metastatic disease if the patient has a primary malignancy elsewhere. On CT, the diagnosis of intrapancreatic splenic tissues should be considered when a well-defined nodule with enhancement paralleling that of the spleen is identified in the pancreatic tail region, particularly along the dorsal surface."
    CT of Splenosis: Patterns and Pitfalls
    Spencer T. Lake, Pamela T. Johnson, Satomi Kawamoto, Ralph H. Hruban, Elliot K. Fishman
     AJR 2012; 199:W686-W693
  • "Splenosis can present with pelvic nodules, which may mimic metastases as well as other entities in women including endometriosis, ovarian masses, and uterine and cervical masses. These nodules may present with pelvic pain, but they are most frequently asymptomatic . Reports of pelvic involvement have included retrovesical and pararectal masses ."
    CT of Splenosis: Patterns and Pitfalls
    Spencer T. Lake, Pamela T. Johnson, Satomi Kawamoto, Ralph H. Hruban, Elliot K. Fishman
     AJR 2012; 199:W686-W693
  • "In patients with a history of splenic trauma or splenectomy, splenosis can arise through- out the abdominal or pelvic cavity in addition to the chest, subcutaneous tissues, and other less common locations. This pictorial essay illustrates many of the possible locations and CT appearances of splenosis to prompt con- sideration of this diagnosis in the appropriate clinical setting"
    CT of Splenosis: Patterns and Pitfalls
    Spencer T. Lake, Pamela T. Johnson, Satomi Kawamoto, Ralph H. Hruban, Elliot K. Fishman
     AJR 2012; 199:W686-W693
  • “CT can be used to differentiate between IPAS and PanNETwith good specificity and sensitivity. The IPAS mirrors the spleen’s enhancement and is usually located along the dorsal surface of the pancreas.”
    Intrapancreatic Accessory Spleen: Possibilities of Computed Tomography in Differentiation From Nonfunctioning Pancreatic Neuroendocrine Tumor
    Coquia SF,Kawamoto S, Hruban RH, Fishman EK
    J Comput Assist Tomogr 2014 (in press)
  • “Although not statistically significant, several other findings are also helpful to differentiate IPAS and neuroendocrine tumors. All IPASs in this study were located at the tip or within 3 cm of the tip of the tail of the pancreas. Therefore, if an enhancing mass is een more than several centimeters from the tip of the tail of the pancreas, it is less likely to represent IPAS and more likely a neuroendocrine tumor.”
    Intrapancreatic Accessory Spleen: Possibilities of Computed Tomography in Differentiation From Nonfunctioning Pancreatic Neuroendocrine Tumor
    Coquia SF,Kawamoto S, Hruban RH, Fishman EK
    J Comput Assist Tomogr 2014 (in press)
  • “ In conclusion, CT can be used to differentiate between IPASs and PanNETs with a high degree of sensitivity and specificity. Specific findings on CT are more prevalent with IPASs and can help increase diagnostic conf idence. These f indings include a lesion that is not completely embedded in the pancreatic parenchyma, a lesion that is located along the dorsal surface of the pancreas, a lesion that shows heterogeneous enhancement at the arterial phase, and a lesion that has the same degree of en- hancement of the spleen at the venous phase.”
    Intrapancreatic Accessory Spleen: Possibilities of Computed Tomography in Differentiation From Nonfunctioning Pancreatic Neuroendocrine Tumor
    Coquia SF,Kawamoto S, Hruban RH, Fishman EK
    J Comput Assist Tomogr 2014 (in press)
  • “The reader should look for enhancement of the IPAS matching the enhancement pat- tern of the spleen on multiphase CT examination. Furthermore, routine evaluation of the splenic vein should be performed with each lesion as occlusion of the vein has been associated with non- functioning PanNETs.”
    Intrapancreatic Accessory Spleen: Possibilities of Computed Tomography in Differentiation From Nonfunctioning Pancreatic Neuroendocrine Tumor
    Coquia SF,Kawamoto S, Hruban RH, Fishman EK
    J Comput Assist Tomogr 2014 (in press)
  • “In cases where the reader finds the lesion as indeterminate, although most were ultimately PanNETs in our study, given the associated decline in overall reader specificity seen in our study, the CT reader should recommend confirmatory testing such as 99mTc-labeled heat-damaged red blood cell scintigraphy or MRI rather than an observation with fine needle aspiration as needed for confirmatio.”
    Intrapancreatic Accessory Spleen: Possibilities of Computed Tomography in Differentiation From Nonfunctioning Pancreatic Neuroendocrine Tumor
    Coquia SF,Kawamoto S, Hruban RH, Fishman EK
    J Comput Assist Tomogr 2014 (in press)
  • “After traumatic splenic injury or splenectomy, small isolated spleens may develop. These implants are not limited to the left upper quadrant, and splenosis in other locations can mimic other pathologic entities. This pictorial essay presents the range of appearances of intraabdominal and pelvic splenosis.”
    CT of splenosis: patterns and pitfalls.
    Lake ST, Johnson PT, Kawamoto S, Hruban RH, Fishman EK.
    AJR 2012 Dec;199(6)W686-93
  • “ In addition to conventional morphologic MR imaging, DW (diffusion weighted) imaging can be used as a tool for differentiating intrapancreatic accessory spleen (IPAS) from solid pancreatic tumors.”
    Differentiation of an Intrapancreatic Accessory Spleen from a Small (<3-cm) Solid Pancreatic Tumor: Value of Diffusion-weighted MR Imaging
    Jang KM et al
    Radiology 2013; 268:159-167
  • “The diagnosis and differentiation of intrapancreatic accessory spleen from a solid pancreatic tumor by using visual assessment of similarity between pancreatic lesions and spleen on diffusion weighted images yields high diagnostic accuracy (90-95%), sensitivity (95-100%), specificity (86-91%), positive predictive value (86-91%) and negative predictive value (95-100%).”
    Differentiation of an Intrapancreatic Accessory Spleen from a Small (<3-cm) Solid Pancreatic Tumor: Value of Diffusion-weighted MR Imaging
    Jang KM et al
    Radiology 2013; 268:159-167
  • Intrapancreatic Accessory Spleen: CT Findings
    CT attenuation and enhancement pattern
    - Similar enhancement on noncontrast and postcontrast scans
    - Arterial phase enhancement is similar to the spleen including the serpiginous pattern of enhancement
  • Intrapancreatic Accessory Spleen: Differential Dx
    - Neuroendocrine tumor (NETs)
    - Metastatic renal cell carcinoma to the pancreas
    - Splenic artery aneurysm
  • “ However, when it remains difficult to exclude the other diagnosis, 99m-Tc labeled HDRBC scintigraphy or SPIO-enhanced MR imaging can be used to confirm the diagnosis of IPAS, with the caveats described above.”
    Intrapancreatic accessory spleen: CT appearance and differential diagnosis
    Kawamoto S, Johnson PT, Hull H, Cameron JL, Hruban RH, Fishman EK
    Abdom Imaging (2012)37:812-827
  • "Typically, accessory spleens appear on CT scans as well marginated, round masses that are smaller than 2 cm and enhance homogeneously on contrast-enhanced images. When accessory spleens are smaller than 1 cm, their attenuation may be lower than that of the spleen because of partial volume effects."

    CT Features of the Accessory Spleen
    Mortele KJ et al.

  • "Typically, accessory spleens appear on CT scans as well marginated, round masses that are smaller than 2 cm and enhance homogeneously on contrast-enhanced images."

    CT Features of the Accessory Spleen
    Mortele KJ et al.
    AJR 2004; 183:1653-1657
  • Accessory Spleen: Facts

    "Differentiation from a hypervascular pancreatic neoplasm (e.g. islet cell tumor) is, therefore sometimes challenging."

    CT Features of the Accessory Spleen
    Mortele KJ et al.
  • Accessory Spleen: Facts
    - Present in 16% of patients undergoing contrast enhanced CT
    - Usually 2 cm or less in size
    - Usually enhance equal to the normal spleen but lesions under 1 cm may not
    - May simulate pancreatic, renal or adrenal pathology