Imaging Pearls ❯ Spleen ❯ Accessory Spleen and Splenules
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- "The spleen is an intraperitoneal organ usually situated in the left upper quadrant of the abdomen; however, in the instance that it is not found in its typical location or orientation, it is referred to as a wandering or ectopic spleen . The cause of this condition is associated with ligamentous hyperlaxity or absence, which can often be acquired through pregnancy, splenomegaly, or through congenital factors . Due to the ligament’s laxity, the vascular pedicle is elongated, often leading to splenic torsion and infarction, which can ultimately lead to necrosis, ischemia, and even splenic rupture.
Wandering spleen with torsion and infarction: A case report
Elias Lugo-Fagundo, Elliot K. Fishman
Radiology Case Reports 17 (2022) 3377-3379 - “This article reviews a case of wandering spleen, an extremely rare condition in which the spleen, normally found in the left upper quadrant, is found in an abnormal anatomical position. The spleen is fixed into position by the splenorenal, spleno- colic, and gastrosplenic ligaments; however, the hyperlaxity or absence of the peritoneal ligaments, due to either acquired or congenital factors, can cause the spleen to shift to a more caudal location . As a result of the ligament’s hyperlaxity, the vascular pedicle is abnormally elongated leading to torsion, which can range from mild (90) to severe (2160), and splenic infarction. Correlated with a strong female predominance, especially in women of reproductive ag , the diagnosis of ectopic spleen presents a challenge due to its nonspecific symptoms.”
Wandering spleen with torsion and infarction: A case report
Elias Lugo-Fagundo, Elliot K. Fishman
Radiology Case Reports 17 (2022) 3377-3379
- “Splenosis is an acquired form of ectopic splenic tissue that typically arises after trauma or splenectomy. It is often an incidental image finding in an otherwise asymptomatic patient, but the spectrum of symptoms varies based on the site of implantation. Radiologists should be familiar with the imaging features of splenosis to avoid mistaking it for malignancy. Splenosis has identical imaging features to that of the native spleen on US, CT, MRI, and nuclear medicine examinations. Therefore, when the radiologic findings support the diagnosis of splenosis, the patient can be spared invasive procedures for tissue sampling.”
Abdominal and pelvic splenosis: atypical findings, pitfalls, and mimics
Travis Smoot et al.
Abdominal Radiology 2022 https://doi.org/10.1007/s00261-021-03402-3 - “Ectopic splenic tissue can be found in the body in three forms: Splenosis, accessory spleen, or wandering spleen. Splenosis is the acquired form of ectopic splenic tissue that arises after traumatic splenic rupture or splenectomy. When the capsule of the spleen is disrupted, splenic auto- implantation can occur throughout the body by direct seeding or hematogenous spread. Splenosis is often an incidental finding, as most patients are asymptomatic, so the true incidence is unknown. However, studies suggest that up to 67% of patients with a compromised splenic capsule develop splenosis.”
Abdominal and pelvic splenosis: atypical findings, pitfalls, and mimics
Travis Smoot et al.
Abdominal Radiology 2022 https://doi.org/10.1007/s00261-021-03402-3 - “If the diagnosis of splenosis remains uncertain on CT or MRI, a Tc99m-labeled Sulfur colloid (Tc-99 m-SC) or heat-dam- aged RBC (Tc-99 m-HDRBC) scan may be helpful given their high sensitivity and specificity for detection of ectopic splenic tissue. Using these radiologic methods, radiologists can distinguish splenosis from other lesions in a timely manner without excessive or undue invasive procedures.”
Abdominal and pelvic splenosis: atypical findings, pitfalls, and mimics
Travis Smoot et al.
Abdominal Radiology 2022 https://doi.org/10.1007/s00261-021-03402-3 - “The peritoneal cavity is a common site of abdominopelvic splenosis. Peritoneal splenosis can be found in various locations including the parietal peritoneum, peritoneal ligaments, mesentery, greater omentum, and serosal surfaces of the large and small bowel. Peritoneal splenosis can present as a single or multiple variable sized soft tissue masses. It can occur in isolation or in conjunction with other involved organs.”
Abdominal and pelvic splenosis: atypical findings, pitfalls, and mimics
Travis Smoot et al.
Abdominal Radiology 2022 https://doi.org/10.1007/s00261-021-03402-3 - "The imaging features of peritoneal splenosis can mimic primary or secondary peritoneal tumors (notably peritoneal carcinomatosis) or endometriosis in cases of pelvic implants. Solitary peritoneal splenosis can be confused with other peritoneal lesions such as peritoneal metastasis, carcinoid tumor, inflammatory pseudotumor, and solitary fibrous tumor. The differentiation of multiple peritoneal splenosis from peritoneal carcinomatosis becomes more difficult in patients with known underlying malignancy. Both history and radionucleotide scintigraphy have a pivotal role differentiating both entities.”
Abdominal and pelvic splenosis: atypical findings, pitfalls, and mimics
Travis Smoot et al.
Abdominal Radiology 2022 https://doi.org/10.1007/s00261-021-03402-3 - "Splenosis, accessory spleen, and wandering spleen must be considered when evaluating ectopic splenic tissue. For patients with a newly identified mass within the abdomen or pelvis, a careful history of splenic rupture or splenectomy can help guide clinicians toward the diagnosis of splenosis. It is often an incidental imaging finding in an otherwise asymptomatic patient, but the spectrum of symptomatic presentation varies based on the site of implantation. The imaging features of splenosis can overlap with other abdominopelvic masses according to the site of implant tion. Splenosis has identical imaging features to that of the native spleen on US, CT and MRI. However, these common imaging modalities may not differentiate splenosis from metastatic lesions particularly in patients with known history of primary malignancy. A definitive diagnosis for such complex cases can be made by radionuclide imaging using Tc99m-labeled sulfur colloid or Tc99m-labeled HDRBC, avoiding unnecessary, invasive diagnostic or therapeutic methods.”
Abdominal and pelvic splenosis: atypical findings, pitfalls, and mimics
Travis Smoot et al.
Abdominal Radiology 2022 https://doi.org/10.1007/s00261-021-03402-3
- "Splenosis typically consists of multiple small implants of splenic tissue; it can mimic peritoneal carcinomatosis or endometriosis depending on the clinical context.”
Polysplenia syndrome
B. De La Villeon et al.
Journal of Visceral Surgery,Volume 148, Issue 5,2011, Pages e395-e396, - "The syndrome of polysplenia is often accompanied by a variable spectrum of visceral and vascular developmental anomalies. It is rarely diagnosed in adults. While it is estimated that 2.5/100,000 infants are born with this anomally, fewer than 5% are still alive at five years of age due to the associated severe cardiac anomalies.The syndrome is associated with multiple congenital malformations that may involve the solid organs and digestive tube of the abdominal cavity, the heart, or the great vessels. The diagnosis is often made during surgical exploration for an associated cardiac or digestive anomaly. Among the most common vascular anomalies are agenesis of the suprarenal inferior vena cava with persistent continuity of the azygos vein, and pre-duodenal position of the portal vein. Biliary atresia is found in nearly 50% of cases, common mesentery in more than 75% of cases, and an abbreviated or annular pancreas in 85–90% of cases.”
Polysplenia syndrome
B. De La Villeon et al.
Journal of Visceral Surgery,Volume 148, Issue 5,2011, Pages e395-e396 - “ Anomalies include asplenia, the congenital absence of the spleen. This can be isolated or part of a clinical sequela of a broader syndrome such as Ivermark syndrome, a heterotaxy syndrome occurring in 1 in 10,000 to 40,000 cases. CT will show lack of spleen and Tc-99 red blood cell scan will show lack of uptake.”
MDCT Findings of Splenic Pathology
Sangster GP et al.
Current Problems in Diagnostic Radiology 2021 (in press) - "Accessory spleen is a frequent congenital variation (20% of autopsy) due to failure in coalescence of mesodermal buds in the dorsal mesogastrium.The accessory spleen is supplied by the splenic artery and most are located near the splenic hilum. On pre- and post-contrast imaging, this enhances similarly to splenic parenchyma. This entity is important to recognize because it could be responsible for the recurrence of hematologic disorders after splenectomy.”
MDCT Findings of Splenic Pathology
Sangster GP et al.
Current Problems in Diagnostic Radiology 2021 (in press) - "Splenosis in an acquired condition that occurs after splenectomy or splenic rupture is represented by seeding or implantation of splenic cells in any location, frequently simulating tumors. On pre- and post-contrast, imaging, splenosis appears similar to the normal spleen. When ectopic splenic tissue or splenosis is in the differential for a mass around the splenic hilum or splenectomy bed, a technetium tagged heat-damaged red blood cell scan is a nuclear medicine examination that can delineate ectopic splenic tissue. Splenosis is usually managed conservatively and history is key to help differentiate it from other lesions.”
MDCT Findings of Splenic Pathology
Sangster GP et al.
Current Problems in Diagnostic Radiology 2021 (in press) - Anatomy of the spleen
Macroscopic anatomy
- An intraperitoneal organ, almost entirely surrounded by the peritoneum, which firmly adherent to the capsule.
- The splenic hilum is usually directed anteromedially, and the splenic artery and vein enters the spleen in this region through the splenorenal ligament.
- The splenorenal and gastrosplenic ligaments are the two folds of peritoneum that hold the spleen in its position.
- Normal splenic size: approximately 200g, 12 cm length, 3-4 cm thickness, 7 cm width.
Histological anatomy
- Red pulp: Complex network of sinusoids and splenic cords
-- Functions as a filter and blood flow regulator
-- The site of erythrocyte storage and macrophage proliferation and differentiation
- White pulp: Consists of lymphatic tissue, contains germinal centers.
-- The site of the spleen’s immunological and cytopoietic function
- Marginal zone: An ill-defined interphase between red/white pulp.
- Transient heterogeneous pattern of contrast enhancement is thought to be related to the variable rates of blood flow through the red/white pulp. - Normal Variant Anatomy of the Spleen
Splenic cleft and lobulation
- The cleft on the superior border are remnants of the groves that originally separated the fetal lobules, and can simulate lacerations.
Accessory spleen
- Found in 10-20% of individuals.
- Within the tail of the pancreas is the second common site of the accessory spleen, and can mimic hypervascular pancreatic tumor (e.g. neuroendocrine tumor)
- Accessory spleen can be a site of relapse of hypersplenism after splenectomy in patients with a hematologic disorder with hypersplenism.
Splenosis
- Ectopic splenic tissue caused by autotransplantation of splenic cells resulting from traumatic disruption of the splenic capsule via trauma or surgery.
- More numerous and widespread than accessory spleens. - Normal Variant Anatomy of the Spleen
Wandering spleen
- The spleen migrate from its normal position due to congenital or acquired laxity of the splenic suspensory ligament.
- At risk of vascular pedicle torsion and splenic infarct.
Polysplenia
- A rare complex syndrome, consists of situs ambiguous with features of left isomerism (bilateral left-sidedness)
- Multiple spleen in right or left upper quadrant, single, lobulated spleen, or a normal spleen
- Anomalous position of abdominal viscera, short pancreas, abnormal bowel rotation, cardiovascular anomalies
Asplenia
- Absent spleen, situs ambiguous, multiple anomalies including cardiovascular anomalies (typically more complex than those with polysplenia), bowel malrotation, genitourinary tract anomalies. - Normal Variant Anatomy of the Spleen
Accessory spleen
- Found in 10-20% of individuals.
- Within the tail of the pancreas is the second common site of the accessory spleen, and can mimic hypervascular pancreatic tumor (e.g. neuroendocrine tumor)
- Accessory spleen can be a site of relapse of hypersplenism after splenectomy in patients with a hematologic disorder with hypersplenism.
Splenosis
- Ectopic splenic tissue caused by autotransplantation of splenic cells resulting from traumatic disruption of the splenic capsule via trauma or surgery.
- More numerous and widespread than accessory spleens. - Normal Variant Anatomy of the Spleen
Polysplenia
- A rare complex syndrome, consists of situs ambiguous with features of left isomerism (bilateral left-sidedness)
- Multiple spleen in right or left upper quadrant, single, lobulated spleen, or a normal spleen
- Anomalous position of abdominal viscera, short pancreas, abnormal bowel rotation, cardiovascular anomalies
Asplenia
- Absent spleen, situs ambiguous, multiple anomalies including cardiovascular anomalies (typically more complex than those with polysplenia), bowel malrotation, genitourinary tract anomalies. - Normal Variant Anatomy of the Spleen
Wandering spleen
- The spleen migrate from its normal position due to congenital or acquired laxity of the splenic suspensory ligament.
- At risk of vascular pedicle torsion and splenic infarct. - Pitfalls in Evaluation of the Spleen
- Splenic tissue simulating an islet cell tumor of the pancreas (usually accessory spleen)
- Splenic tissue in the pancreas simulating an islet cell tumor
- Post left nephrectomy splenic rotation simulating a tumor recurrence - “Wandering spleen is a very rare defect characterized by the absence or weakness of one or more of the ligaments that hold the spleen in its normal position in the upper left abdomen. Patient symptomatology is variable and ranges from mere feeling of an abdominal lump to sudden abdominal pain due to infarction. Patients may have subacute to chronic abdominal or gastrointestinal complaints. Because of nonspecific symptoms, clinical diagnosis can be difficult; hence, imaging plays an important role. A major complication is splenic torsion, which is the cause of acute abdomen.”
Acute abdomen due to torsion of the wandering spleen in a patient with Marfan Syndrome
Laura Leci-Tahiri et al.
World Journal of Emergency Surgery 2013, 8:30 - “The possible diagnosis of wandering spleen should be kept in mind when CT shows the spleen to be absent from its usual position and a mass is found elsewhere in the abdomen or pelvis. Abdominal ultrasonography (with or without Doppler) and CT are useful investigative tools. Early intervention is necessary to reduce the risk of splenic infarction and other complications. An awareness of the condition together with the use of appropriate medical imaging can lead to the correct diagnosis.”
Acute abdomen due to torsion of the wandering spleen in a patient with Marfan Syndrome
Laura Leci-Tahiri et al.
World Journal of Emergency Surgery 2013, 8:30
- Background: Identification of incidental pancreatic lesions is increasing because of advancements in imaging. Diagnosis remains a challenge for clinicians, with intrapancreatic accessory spleens (IPAS) posing a unique dilemma. IPAS are frequently resected because of inability to exclude alternate diagnoses, subjecting patients to unnecessary risk. The purpose of this study was to examine our institutional experience with IPAS and develop a multidisciplinary algorithm to improve preoperative diagnosis.
Conclusions: Incidental pancreatic lesions like IPAS remain a diagnostic challenge for clinicians. Employing a diagnostic algorithm as proposed may aid in the distinction of malignant and premalignant pathology and prevent unwarranted pancreatic resections.
Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152 - “Ten patients of 303 patients who underwent a distal pancreatectomy were identified with a final pathology of IPAS. The average age was 54 y, 80% were white, and 60% were male. Lesions ranged in size from 7 mm to 5.1 cm in largest diameter (mean 2.2 cm). Lesions were described as round, well-marginated, and enhancing masses within the pancreatic tail. Preoperative workup was variable in terms of imaging and laboratory testing. Diagnostic workups were examined and combined with multidisciplinary input to create a diagnostic algorithm.”
Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152 - “IPAS are the result of splenic tissue buds failing to fuse during embryologic development and are quite common, found in 10%-20% of individuals. Accessory splenic tissue is usually asymptomatic and found incidentally with the most common location in the splenic hilum. However, 10%-15% are found in the pancreatic tail where they pose a diagnostic predicament.”
Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152 - Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens Baugh KA et al. J Surg Res. 2019 Apr;236:144-152
- On CT, IPAS appears as solid heteroge- neously enhancing masses, size averages 1-3 cm, and most commonly within 3 cm of the tail of the pancreas. Similarly, 90% of our patients had an enhancing distal mass with a mean maximum diameter less than 3 cm. The attenuation of accessory splenic tissue is similar to the spleen on arterial and venous phases, which was commented on in only two of the initial CT reports.
Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152 - “The heterogeneous enhancement on arterial phase is secondary to the differences in rate of blood flow between the red pulp and the white pulp of the spleen. Nonfunctioning PNETs are also hyperenhancing lesions on CT but with uniform or ring-like enhancement and greater enhancement on the venous phase.”
Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152 - “Metastatic disease represents 2%-5% of all malignant pancreatic tumors and usually arises from renal cell carcinoma, non-small cell lung cancer, and gastrointestinal carcinoma. Renal cell carcinoma usually presents as an enhancing lesion, whereas the other two are usually hypoattenuating but all typically correlate with the discovery of a primary tumor on CT.”
Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152 - ”The octreoscan is 70%-95% sensitive for detecting PNETs with somatostatin receptors. However, not all PNETs have somatostatin receptors; therefore, a negative octreotide scan does not rule out PNETs. In addition, lymphocytes can also display somatostatin receptors on their surface and cause uptake of the radiolabeled analog creating a false positive. One of the two IPAS patients in our series had a false positive octreotide scan; this displays the challenges that persist in diagnosing incidental pancreatic lesions.”
Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152 - “Diagnosis of incidental distal pancreatic solid lesions like IPAS creates significant difficulty for pancreas surgeons. Our algorithm provides needed structure to the work up. Although this is designed to rule out IPAS, this algorithm can be used as a starting point for the work up of any incidentally found pancreatic mass. In the past, the work up of incidentally found lesions led to the development of useful guidelines in the adrenal gland. Therefore, establishment of protocols like the one proposed for pancreatic lesions may aid in the development of future guidelines for the pancreas.”
Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152 - “Work up of an incidental pancreatic solid lesion remains a challenge, especially for the diagnosis of IPAS. Successful diagnosis will require a strong index of suspicion, a multi- disciplinary approach, and the use of the proposed algorithm. In time, this may aid clinicians in the distinction between benign IPAS, which requires no further action and a lesion requiring resection.”
Pancreatic Incidentalomas: A Management Algorithm for Identifying Ectopic Spleens
Baugh KA et al.
J Surg Res. 2019 Apr;236:144-152
- "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