Pathologists have limited exposure to neoplastic disorders that involve the spleen. This course is intended for hematopathologists, surgical pathologists, and residents or fellows in training who deal with spleen specimens. The major objective of the course will be to discuss diagnostic criteria of splenic neoplasms. A series of ten relevant case studies will be used for discussion, with primary emphasis on comprehensive integration of clinicopathologic findings including: immunohistochemistry, flow cytometry, cytogenetics, and molecular diagnostics. Topics to be presented will include: splenic manifestations of B-cell lymphoid neoplasms (including small lymphocytic lymphoma/chronic lymphocytic leukemia, lymphoplasmacytic lymphoma hairy cell leukemia, splenic marginal zone lymphoma, follicular lymphoma, mantle cell lymphoma, large cell lymphoma), T-cell lymphoid neoplasms (including T-cell granular lymphocytic leukemia, hepatosplenic T-cell lymphoma), and Hodgkin lymphoma. Splenic involvement by myloid neoplasms (including chronic myeloproliferative disorders, myelodysplastic/myeloproliferative diseases, and extramedullary acute leukemia), mast cell disease, Langerhans cell histiocytosis, and malignant histiocytosis will also be discussed. Selected splenic non-hematologic tumors (including vascular tumors, stromal neoplasms, and metastatic diseases) will also be covered. Case histories and a limited number of loan sets of microscopic slides will be available for advanced mailing. A CD-ROM with microscopic images, and lecture materials will be mailed after the meeting. A detailed syllabus will be distributed at the course.