Factors impacting the information available from a needle aspirate:
(1) adequacy of the sample and the amount of material required to make a diagnosis
(2) distribution and size of the pathologic process
(3) context of the splenic process
Adequacy of material:
(1) The aspirate may consist only of blood or miss the spleen entirely.
(2) Some lesions can be diagnosed on a small amount of material:
(2a) infectious agent (culture, PCR, etc)
(2b) lymphoproliferative disorder (flow cytometry)
(2c) malignancy (characteristic Immunoperoxidase pattern)
Distribution of the pathologic process:
(1) A diffuse process can be sampled by a "blind" aspirate.
(2) The sampling of a localized process should be image-directed.
(3) A localized process that is small may be easily missed.
Context of the splenic process:
(1) Determining if a lesion is a metastasis from a known tumor is easier than trying to diagnose a previously undiagnosed tumor.
(2) A primary splenic tumor may be more difficult to diagnose on limited material.
(3) The lesion aspirated may be completely unexpected.
