Approach Considerations
Initial evaluation of the patient with splenomegaly should include the following:
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Complete blood cell count (CBC) with differential
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Evaluation of peripheral blood smear for red blood cell (RBC) morphology and signs of myeloproliferative disorders or underlying bone marrow disorder
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Liver function testing, including coagulation studies
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Hepatitis B and C testing
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Lactate dehydrogenase (LDH)
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Urinalysis
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Chest x-ray
Those studies can help identify various causes of splenomegaly, such as sickle cell disease, spherocytosis, and other hereditary hemolytic anemias. If the differential count reveals a lymphocyte predominance, flow cytometry should be performed. Results consistent with neoplasm may prompt fluorescence in situ hybridization (FISH) or polymerase chain reaction (PCR) testing for BCR-ABL or Jak 2. Depending on the apparent etiology, bone marrow biopsy may be needed.
If this initial workup does not yield a diagnosis, then the clinician can evaluate for an underlying disease state with the following, based on clinical appropriateness:
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Biopsy of suspicious lymph nodes
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Bone marrow aspirate and biopsy to evaluate for myeloproliferative and lymphoproliferative disease as well as disseminated infection
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Liver biopsy
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Flow cytometry of the peripheral blood, to assess for an indolent lymphocytic leukemia (eg, hairy cell leukemia, chronic lymphocytic leukemia) that may be causing splenic enlargement
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Erythrocyte sedimentation rate (ESR) to screen for subacute/non-fulminant infectious syndromes
Clinically detected splenomegaly is confirmed and quantified using imaging studies. Ultrasonography is a noninvasive, highly sensitive, and specific imaging technique for the evaluation of splenic size. Point-of-care ultrasonography significantly improved the sensitivity of physical examination alone in diagnosing splenomegaly in a prospective study of 39 adult hospitalized patients. [14]
On imaging studies, the upper limit of normal splenic size is frequently defined as a craniocaudal measurement of 11-13 cm. However, because of wide variations in splenic shape, no consistent correlation has been recognized between the spleen's length and its overall volume, as has been determined for other organs (eg, kidney).
Angiographic findings are used to differentiate splenic cysts from other splenic tumors. Splenoportography is used to evaluate portal vein patency and the distribution of collateral vessels before shunt operations for cirrhosis. Splenoportographic findings can help to identify the cause of idiopathic splenomegaly, especially in children.
Findings in Hypersplenism
The term hypersplenism describes some of the sequelae that are often observed with splenomegaly. Criteria for a diagnosis of hypersplenism include the following:
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Splenomegaly
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Anemia, leukopenia, thrombocytopenia, or combinations thereof
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Cellular bone marrow
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Improvement after splenectomy
The mechanisms for those blood count abnormalities are as follows:
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Anemia - The anemia observed in splenomegaly results from sequestration and hemodilution.
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Leukopenia - Increased destruction or sequestration of leukocytes causes the leukopenia observed in splenomegaly. Leukopenia is closely related to neutropenia. Neutropenia (absolute neutrophil count [ANC] < 1800/μL) is the result of an increase in the marginated granulocyte pool, a portion of which is located in the spleen (see the Absolute Neutrophil Count calculator). Sequestration may also play a role in the genesis of neutropenia.
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Thrombocytopenia - Increased splenic platelet pooling is the primary cause of the thrombocytopenia of hypersplenism. Normally, approximately 30% of the total platelet mass exists as an exchangeable pool in the spleen; in patients with hypersplenism, as much as 90% of the total platelet mass can be found in the spleen. In hypersplenism, the platelet count is usually 50,000-150,000/µL.
Splenectomy and Splenic Biopsy
History and physical examination, laboratory studies, and CT scanning can help clinicians to determine the etiology of splenomegaly in greater than 90% of cases. Occasionally, however, it is necessary to obtain splenic tissue for pathologic evaluation.
Splenectomy
Splenectomy may be considered in certain individuals to determine the etiology of splenomegaly, though early diagnostic splenectomy is rarely indicated. [15, 16, 17, 18, 19, 20] The need for a diagnosis must be carefully weighed against the morbidity associated with the asplenic state and should be pursued only after other means of diagnosis have been exhausted. Splenectomy is typically performed laparoscopically; even supramassive spleens can be removed by laparoscopic surgery with minimal morbidity. [19, 21] Splenectomy is therapeutic in individuals with severe pancytopenia due to splenomegaly.
Splenic biopsy
Splenic biopsy may be performed in specialized institutions, though is rarely indicated. Severe bleeding is a frequent complication that limits the usefulness of this procedure. Mosquera-Klinger et al reported that endoscopic ultrasound (EUS)–guided fine needle aspiration proved a safe and effective technique for obtaining splenic biopsy samples. In their review of EUS-guided splenic punctures in 15 patients, no patient experienced immediate or delayed complications related to the procedure. [22]
Histologic evaluation
When referring to an enlarged spleen as hypertrophied, the underlying cause may be hypertrophy or hyperplasia of individual cells. In specific diseases, the splenic architecture is remodeled. For example, in Niemann-Pick disease, sphingomyelin and cholesterol accumulate within large foamy cells, which is characteristic of this disease.
With amyloidosis involving the spleen and resulting in splenomegaly, large hyaline masses are seen as lesions occupying the white pulp space. Two forms exist, including the "sago spleen," in which amyloid deposits are limited to follicles, and the "lardaceous spleen," in which amyloid is deposited in the walls of the splenic sinusoids. In a rare complication of typhoid fever, reactive splenic vasculitis may develop.
Imaging Studies
Computed tomography
The underlying histologic anatomy of the spleen largely determines its characteristic appearance on abdominal computed tomography (CT) scans. On unenhanced CT scans, the spleen has an attenuation similar to that of the liver, approximately 40 Hounsfield units (H). Normally, the liver and spleen densities are within 25 H on dynamic contrast-enhanced CT scans. [23]
In general, the spleen can be considered enlarged if its craniocaudal length is more than 10 cm on conventional CT scans. A spleen that extends below the lower third pole of the kidney is also indicative of splenomegaly.
A CT scan remains the most useful preoperative investigation to measure splenic volume; to exclude lymph nodes at the splenic hilum; and to detect accessory spleens, splenic abscesses, and perisplenitis.
Findings that indicate radiologic distinction between benign and malignant lesions are inconsistent and cannot be relied on to establish or refute a diagnosis of malignancy.
CT scanning is the imaging study of choice for identification of inflammatory changes. In addition, CT scanning is sensitive for detecting mass lesions, calcifications, infarcts, and cysts.
Liver-spleen colloid scan
For spleen scanning, erythrocytes are labeled with chromium-51 (51Cr) , mercury-197 (197Hg), rubidium-81 (81Rb), or technetium-99m (99mTc), and the cells are altered by treatment with heat, antibody, chemicals, or metal ions so that the spleen will sequester them after infusion. A splenic length of greater than 14 cm is considered enlarged on liver-spleen scan
A spleen scan is a good noninvasive technique for evaluating splenic size; a close correlation exists between splenic length on the scan images and splenic weight after splenectomy.
A spleen scan is also useful for detecting space-occupying lesions in the splenic substance, evaluating loss of splenic functions, assessing for the absence of a spleen, or determining the presence of an accessory spleen.
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This patient has a splenic abscess due to pneumococcal bacteremia. Note that the massively enlarged spleen is readily visible, with minimal retraction in the left upper quadrant.
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Resected specimen from the patient in the previous image. Note the discrete abscesses adjacent to normal parenchyma.
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The margins of this massive spleen were palpated easily preoperatively. Medially, the 3.18 kg (7 lb) spleen crosses the midline. Inferiorly, it extends into the pelvis.
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Massive splenomegaly does not preclude splenectomy through a minimally invasive approach. This photograph depicts a fragmented 3.2 kg (7.05 lb) spleen after removal via a hand-assisted laparoscopic technique.
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A portion of a massive spleen is extracted via hand-assisted laparoscopy.
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Intraoperative photograph of a laparoscopic splenectomy being taken down using the hanging-pedicle technique. The tip of the spleen is visualized in the background, whereas the stapler is detailed in the foreground across a segment of the pedicle.
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A massive spleen that was removed from an elderly woman with lymphoma.
