- Author: Neetu Radhakrishnan, MD; Chief Editor: Emmanuel C Besa, MD more...
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.
In imaging studies, a craniocaudal measurement of 11-13 cm is frequently used as the upper limit of normal splenic size. However, because of wide variations in 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.
Perform a complete blood count (CBC) with differential, platelet count, and peripheral blood smear in cases of splenomegaly. These studies can identify 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.
Findings in Hypersplenism
The term hypersplenism describes some of the sequelae that are often observed with splenomegaly. Criteria for a diagnosis of hypersplenism include anemia, leukopenia, thrombocytopenia, or combinations thereof, plus cellular bone marrow, splenomegaly, and improvement after splenectomy.
The anemia observed in splenomegaly results from sequestration and hemodilution.
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.
Approximately 30% of the total platelet mass exists as an exchangeable pool in the spleen. Increased splenic platelet pooling is the primary cause of the thrombocytopenia of hypersplenism. 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.
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.
In general, the spleen can be considered enlarged if its craniocaudal length is more than 10cm 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 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 sequesters them after infusion. A splenic length of greater than 14 cm is consider 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.
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 may be considered in certain individuals to determine the etiology of splenomegaly.[13, 14, 15, 16, 17] However, the need for a diagnosis must be carefully weighed against the confounding morbidity associated with the asplenic state. Splenectomy is typically performed laparoscopically; even supramassive spleens can be removed by laparoscopic surgery with minimal morbidity.[17, 18] Splenectomy is therapeutic in individuals with severe pancytopenia due to splenomegaly.
Splenic biopsy may be performed in specialized institutions. Severe bleeding is a frequent complication that limits the usefulness of this procedure.
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.
Laboratory studies include the following:
Complete blood cell count (CBC) with differential
Liver function testing
Hepatitis B and C testing
Lactate dehydrogenase (LDH)
Erythrocyte sediumentation rate (ESR)
Evaluation of peripheral blood smear for RBC morphology and signs of myeloproliferative disorders or underlying bone marrow disorders
Prothrombin time with international normalized ratio (INR) and activated partial thromboplastin time (aPTT)
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