Splenic infarction

Associate Editor-In-Chief:

Overview
Splenic infarct is a rare form of pathology. The infarct may be segmental or global, involving the entire organ. It is the result of arterial or venous compromise, and it is associated with a heterogeneous group of diseases. Surgery is indicated only in the presence of complications such as hemorrhage, rupture, abscess, or pseudocyst.

Due to the increasing use of abdominal imaging, splenic abscess, which formerly was recognized only at the time of laparotomy or pathologic examination of the resected spleen, is now being diagnosed with increasing frequency. This has led to the realization that an uncomplicated splenic infarct without associated infection and/or abscess can be treated non operatively.

Related Anatomy
The arterial supply to the spleen consists of the splenic artery (a branch of the celiac axis) and the short gastric arteries (branches of the left gastroepiploic artery), which supply the upper pole of the spleen. Even with occlusion of the main splenic artery, collateral flow from the short gastric arteries often may preserve some or all of the splenic parenchyma.

Within the spleen, the arterial supply is segmental. Occlusion of these secondary branches results in the classic wedge-shaped infarct. Most commonly, these infarcts contract and fibrose over time, as demonstrated by the sickle hemoglobinopathies in which repeated episodes of infarction ultimately result in auto-infarction of the spleen.

==Etiology       ==

Hematologic disorders - Malignant

 * Leukemia


 * Lymphoma (i.e., Hodgkin lymphoma, Non-Hodgkin lymphoma)


 * Myelofibrosis

Hematologic disorders - Benign

 * Hypercoagulable states


 * Protein C deficiency


 * Protein S deficiency


 * Oral contraceptives


 * Lupus anticoagulant


 * Erythropoietin therapy


 * Idiopathic venous thrombosis


 * Polycythemia vera


 * Sickle hemoglobinopathies

Embolic disorders

 * Endocarditis


 * Atrial fibrillation


 * Prosthetic mitral valve


 * Paradoxical emboli from right heart


 * Left ventricular mural thrombus following myocardial infarct


 * Infected thoracic aortic graft


 * HIV-associated mycobacterial infections

Autoimmune/collagen vascular disease

 * SLE


 * Kawasaki disease


 * Wegener’s granulomatosis


 * Polyarteritis nodosa

Trauma

 * Blunt trauma


 * Torsion of the wandering spleen


 * Left heart catheterization via femoral artery approach


 * Sclerotherapy of bleeding gastric varices


 * Pitressin infusion


 * Embolization for splenic bleeding

Operative etiologies

 * Pancreatectomy


 * Liver transplantation

Infections

 * Meningococcaemia


 * Kala-azar (visceral leishmaniasis)


 * Infectious mononucleosis


 * Clostridium perfringens


 * Campylobacter fetus


 * Salmonellosis


 * Plasmodium vivax


 * Plasmodium falciparum


 * Leptospirosis

Miscellaneous etiologies

 * Splenic vein thrombosis


 * Pancreatitis


 * Amyloidosis


 * Sarcoidosis


 * Pancreatic cancer


 * Adult respiratory distress syndrome (ARDS)


 * Postpartum toxic shock syndrome

Therapeutic splenic infarction
Splenic infarction can be induced for the treatment of such conditions as portal hypertension or splenic injury. It can also be used prior to splenectomy for the prevention of blood loss.

Epidemiology
Splenic infarction is associated most commonly with hematologic disorders. The propensity for splenic infarction in sickle hemoglobinopathies is well known. The mechanism of splenic infarction in sickle cell disease is attributed to crystallization of the abnormal hemoglobin during periods of hypoxia or acidosis.

The rigid erythrocyte leads to rouleaux formation and occlusion of the splenic circulation. In homozygous sickle cell disease, multiple infarcts during childhood commonly result in a scarred, contracted, auto-infarcted spleen by adulthood.

Exposure to low oxygen tension, such as unpressurized airplane travel, or vigorous activity, such as skiing in high altitude locations, also can precipitate sickling and splenic infarction in individuals heterozygous for the sickle trait. Many of these altitude-related episodes can be safely treated with supportive care rather than with splenectomy (Sheikha, 2005).

Although splenic infarct rates of 50% and 72% have been reported in chronic myelogenous leukemia and myelofibrosis respectively, few large series describing this entity exist.

In 1998, Nores reported 59 cases treated over a 30-year period at the University of California, Los Angeles (UCLA) and Cedars-Sinai Medical Center. In 1986, Jaroch identified 75 patients through clinical or autopsy reports at the Cleveland Clinic and found only an additional 77 cases in the literature. Most of the current literature consists of case reports.

Systemic embolization also can result in splenic infarct. It occurs most commonly in the setting of a left atrial or ventricular mural thrombus formed as the result of acute myocardial infarction.

While autopsy series report a 9% incidence of splenic infarction in early deaths following an acute myocardial infarction, clinical series report a much lower incidence of splenic embolization, probably reflecting the silent clinical course of many splenic infarcts.

Pathophysiology

 * In diseases such as chronic myeloid leukemia that result in massive splenomegaly secondary to the malignant infiltrative process, segmental infarcts are considered the result of outstripping the available blood supply.


 * Splenic vein thrombosis, most commonly the result of pancreatitis or surgery, can result in venous infarction.


 * Unusual causes of splenic infarction include malaria, pancreatitis, cocaine use, and splenic infarction occurring as a late complication of liver transplantation.


 * An anatomic variant that renders the spleen more susceptible to global infarction is that of the wandering spleen. The spleen is attached by a long vascular pedicle, without the usual fixating ligaments, to the diaphragm, colon, left kidney, and lateral abdominal wall. This allows torsion of the freely mobile spleen around its vascular pedicle, occluding the blood supply and leading to infarction. The treatment is surgical fixation of the spleen (i.e., splenopexy), allowing preservation of the spleen if it has not infarcted as a result of occlusion of the splenic hilum. Techniques include suturing the spleen to the surrounding structures, wrapping it in omentum or mesh prior to suture fixation, or placing it in a surgically created retroperitoneal pouch.

Pathomorphology
A. Brief Descriptions：


 * 1) Nearly 99% of infarcts are caused by thromboembolic events, and almost all are the result of arterial occlusions.
 * 2) White infarcts are encountered with arterial occlusion and in solid tissues.

B. Gross Findings：


 * 1) Recent infarcts are hemorrhagic,whereas older, more fibrotic infarcts are pale yellow-gray.

C. Micro Findings：


 * 1) Necrotic area with homogenous pinkish appearance.
 * 2) Hematoidin crystals can be found in this section.
 * 3) Inflammatory cells seated on the margin of infarct area.

Clinical Presentation
The clinical presentation of infarction may vary. They may be discovered incidentally on radiologic or postmortem studies, or hemorrhagic shock as a result of subcapsular haematoma with rupture into the peritoneal cavity.

Approximately one-third of splenic infarcts are clinically occult. The most common presenting symptom is left upper quadrant abdominal pain. Additional symptoms include fever and chills, nausea and vomiting, pleuritic chest pain, and left shoulder pain (Kehr's sign). Septic thromboemboli can result in splenic abscesses, which present with sepsis and left upper quadrant abdominal pain.

Laboratory tests

 * Laboratory tests are not diagnostic for splenic infarction, although in a few cases there is leucocytosis, thrombocytosis, and anaemia.

Imaging Studies
Radiological imaging tests are diagnostic. Ultrasound imaging is useful in cases where the splenic parenchyma can be visualized, but significant amount of luminal bowel gas, as well as morbid obesity, render this modality less useful.


 * Computerized tomography scan is the current diagnostic modality of choice. Prior to the CT era, diagnosis of splenic infarct was made most commonly at laparotomy for intra-abdominal catastrophe or on postmortem examination. An abdominal CT scan is the most commonly used modality to confirm the diagnosis, although abdominal ultrasound can also contribute.  In CT; focal infarcts appear as wedge-shaped areas of decreased attenuation that extend to the surface of the spleen. Global infarction can manifest as diffuse areas of decreased attenuation in the spleen and can mimic splenic abscess or tumor. In some cases of global infarction, the splenic periphery remains enhanced due to perfusion from capsular vessels.

Patient #1 Note peripheral enhancement due to perfusion from capsular vessels

Images courtesy of RadsWiki


 * Contrast studies clearly depict the classic segmental wedge-shaped, low-attenuation defect. Less frequently, the entire spleen may be infarcted, leaving only a rim of contrast-enhancing capsule.


 * Other modes of diagnosis include radioisotope scans and ultrasound evaluation of the spleen.


 * Angiography is indicated when a vascular lesion is suspected as the etiologic cause, as in cases of arterial embolization, or to manage segmental bleeding by embolization.


 * Magnetic resonance imaging is another useful modality that clearly identifies infarcted splenic parenchyma. Magnetic resonance images may be reconstructed easily in 3 dimensions (as can spiral CT scan images) if the images are obtained using gadolinium contrast.

Histolopathological Findings

 * Pathologic examination of the resected spleen may provide information regarding the pathogenesis of the infarct, e.g. evidence of septic or atheromatous emboli or the presence of an infectious etiology.

Treatment
There is no specific treatment, except treating the underlying disorder and providing adequate pain relief. Splenectomy is only required if complications ensue; surgical removal predisposes to overwhelming post-splenectomy infections.

Medical therapy
Surgery is indicated only in the presence of complications. Otherwise, the infarcted spleen can be left in situ, and the patient is observed. Due to the rarity of this disorder and the largely anecdotal character of many reports, the roles of antibiotics and antiplatelet agents (for the treatment of thrombocytosis) have not been formally addressed. Similarly, no scientifically supported information exists regarding the possible increase in susceptibility to overwhelming postsplenectomy sepsis in these patients.

The principal mainstay of medical therapy is analgesia with either narcotics or nonsteroidal anti-inflammatory agents.

In one series of 59 patients, mortality amounted to 5%. Complications include a ruptured spleen, hemorrhage, splenic abscess (for example, if the underlying cause is endocarditis) or pseudocyst formation. Splenectomy may be warranted for persistent pseudocysts due to the high risk of subsequent rupture.

Surgical therapy

 * For an infarcted spleen with any of the above-mentioned complications, splenectomy is required.


 * Because of the small but real risk of fatal overwhelming post splenectomy sepsis, splenic preservation is preferable whenever possible.


 * In cases of torsion of a wandering spleen, splenopexy with splenic salvage is the procedure of choice in the well-perfused, non infarcted spleen.


 * Complications such as bleeding or pseudocyst formation also may be amenable to splenic salvage using techniques of partial splenectomy.


 * While a unilocular abscess can be managed successfully in select cases with percutaneous catheter drainage, some authors advocate splenectomy in all cases of splenic infarct and abscess, questioning the utility of preserving the residual partially functioning spleen. This may be accomplished using traditional open techniques or laparoscopic techniques.


 * Perisplenic inflammation and dense adhesions can make splenectomy difficult. Another choice is to perform preoperative splenic artery embolization, which purposely infarcts the remaining spleen and minimizes blood loss that otherwise can be quite profuse in these difficult dissections.

Intraoperative ligation of the splenic artery at the superior margin of the pancreas in the lesser sac is another alternative to minimize blood loss if the spleen is enlarged.

Contraindications:


 * Asymptomatic infarct without complication does not require surgical intervention.


 * Overall, most splenic infarcts do not require surgical intervention.

Complications

 * Hemorrhage: Hemorrhage can follow splenectomy due to the intense perisplenic inflammation.


 * Splenic bed and/or subphrenic abscess: Abscess is not an uncommon complication. The first line of treatment is radiologic-guided percutaneous drainage.


 * Pancreatic fistula: Because of the intimate association of the pancreatic tail and splenic hilum, pancreatic injury can occur, especially in the setting of intense inflammation and/or abscess. The majority of these resolve with nonoperative management, which includes wide drainage, use of a somatostatin analog to decrease exocrine pancreatic function, and either total parenteral nutrition (TPN) or enteral alimentation distal to the ligament of Treitz.


 * Gastric fistula: Due to the intense inflammatory reaction that can accompany splenic abscess, the dissection of the spleen from the greater curve of the stomach can be difficult, and inadvertent unrecognized injuries to the greater curve of the stomach do occur. With adequate external drainage and with no obstruction to normal gastric emptying, these can be treated expectantly with TPN or distal luminal alimentation and nasogastric tube decompression.


 * Overwhelming postsplenectomy sepsis: As discussed above, the incidence is unknown. The overall postoperative sepsis rate is high because splenectomy often is undertaken for treatment of splenic abscess. The rate of sepsis is due to the cause for the abscess rather than the splenectomy.

Source

 * Guth AA, Pachter HL, Kaplan LJ et. al., Splenic Infarct,

Additional Resources

 * Argiris A: Splenic and renal infarctions complicating atrial fibrillation. Mt Sinai J Med 1997 Sep-Oct; 64(4-5): 342-9[Medline].
 * Balcar I, Seltzer SE, Davis S: CT patterns of splenic infarction: a clinical and experimental study. Radiology 1984 Jun; 151(3): 723-9.
 * Cohen BA, Mitty HA, Mendelson DS: Computed tomography of splenic infarction. J Comput Assist Tomogr 1984 Feb; 8(1): 167-8.
 * Desai DC, Hebra A, Davidoff AM: Wandering spleen: a challenging diagnosis. South Med J 1997 Apr; 90(4): 439-43.
 * Franklin QJ, Compeggie M: Splenic syndrome in sickle cell trait: four case presentations and a review of the literature. Mil Med 1999 Mar; 164(3): 230-3.
 * Goerg C, Schwerk WB: Splenic infarction: sonographic patterns, diagnosis, follow-up, and complications. Radiology 1990 Mar; 174(3 Pt 1): 803-7.
 * Jaroch MT, Broughan TA, Hermann RE: The natural history of splenic infarction. Surgery 1986 Oct; 100(4): 743-50.
 * Kluger Y, Paul DB, Townsend RN: Enhanced rim around infarcted, traumatized spleen on computed tomographic scans: case report. J Trauma 1994 Mar; 36(3): 436-7.
 * Lo AY, Reich H, Harvey J: Splenic infarction associated with adult respiratory distress syndrome. Mt Sinai J Med 1994 Sep; 61(4): 369-71.
 * Nores M, Phillips EH, Morgenstern L: The clinical spectrum of splenic infarction. Am Surg 1998 Feb; 64(2): 182-8.
 * O'Keefe JH Jr, Holmes DR Jr, Schaff HV: Thromboembolic splenic infarction. Mayo Clin Proc 1986 Dec; 61(12): 967-72.
 * Pachter HL, Hofstetter SR, Elkowitz A: Traumatic cysts of the spleen--the role of cystectomy and splenic preservation: experience with seven consecutive patients. J Trauma 1993 Sep; 35(3): 430-6.
 * Pachter HL, Guth AA, Hofstetter SR: Changing patterns in the management of splenic trauma: the impact of nonoperative management. Ann Surg 1998 May; 227(5): 708-17; discussion 717-9.
 * Shackford SR, Wald SL, Ross SE: The clinical utility of computed tomographic scanning and neurologic examination in the management of patients with minor head injuries. J Trauma 1992 Sep; 33(3): 385-94.
 * Sheikha A: Splenic syndrome in patients at high altitude with unrecognized sickle cell trait: splenectomy is often unnecessary. Can J Surg 2005; 48: 377-381.
 * Torda A: Postpartum toxic shock syndrome associated with multiple splenic infarcts. Med J Aust 2005; 182: 93.
 * Walcher F, Schneider G, Marzi I: Torsion of a wandering spleen after blunt abdominal trauma. J Trauma 1997 Dec; 43(6): 983-4.
 * Yu LK, Hsu CW, Liu NJ: Splenic infarction complicated by splenic artery occlusion after N-butyl-2-cyanoacrylate injection for gastric varices: case report. Gastrointest Endosc 2005; 61: 343-345.