Section 3 -

General Considerations on the Diagnosis of Splenic Disorders Attilio Orazi Dennis P. O'Malley

The initial evaluation of the spleen should be based on gross examination of the organ. Useful information on how to approach diagnosis on spleen can be found summarized in Fig. 3-1 as well as in the references [1, 2, 3, 4, 5]. Table 3-1 also provides an overview of patterns of splenic involvement with types of lesions. Two main disease patterns are identified: Diffuse Splenic Enlargement White Pulp Involvement Most disorders of the splenic lymphoid tissue produces a micronodular pattern due to the abnormal expansion of preexisting nodular lymphoid structures (i.e. splenic lymphoid follicles, PALS). Grossly, this appears as multiple small, whitish nodules on the cut surface, which is occasionally referred to as a 'miliary' pattern. This type of pattern is most often seen in small B-cell lymphoid neoplasms involving the spleen. The nodules may on occasion become confluent, or present as larger, dominant masses. Hematologic disorders that affect the white pulp of the spleen are largely the same as those that affect other lymphoid organs. These disorders include Hodgkin lymphoma and non-Hodgkin lymphomas. Red Pulp Involvement Red pulp involvement has a different gross appearance. Typically, the expansion of the red pulp gives the spleen a more homogeneous red or 'beefy' appearance. The normal nodularity of the white pulp is typically diminished or not seen. Microscopically, the white pulp is often atrophic or compressed by the expanded red pulp. Neoplastic proliferations that involve the red pulp include myeloid and lymphoid leukemias, myeloproliferative disorders, and a variety of non-hematopoietic tumors. In general, disorders with a large component of circulating cells (ex. chronic lymphocytic leukemia, large granular lymphocytic leukemia, hairy cell leukemia, acute leukemia) will have significant red pulp involvement. However, some lymphomas (e.g. hepatosplenic T cell lymphoma, intravascular large B cell type) also preferentially involve the red pulp. Focal Splenic Pathology Focal lesions are occasional encountered in the spleen. These may represent neoplastic as well as pseudotumoral lesions. Splenic Rupture Splenic rupture as a primary presentation of hematologic malignancy is rare, but has been reported with both low-grade and high-grade lymphoid malignancies. Splenic rupture is a complication occasionally seen in cases of leukemia. This is believed to result from infiltration by tumor cells of the trabecular framework and vascular structure of the organ or from infarction within the spleen. Rupture of the spleen is far more common in the chronic leukemias (particularly chronic myeloid leukemia) than in the acute forms. Non-hematopoietic lesions can also be associated with splenic rupture, including cysts, infarctions, vascular lesions/neoplasms, and metastatic malignancies. Fig. 3-1. Systematic Splenic Evaluation – Synopsis TABLE 3-1: Patterns of Involvement in Splenic Pathology   PREDOMINATELY WHITE PULP BASED PREDOMINATELY RED PULP BASED DIFFUSE Neoplastic Small B cell lymphomas (CLL/SLL, LPL, SMZL, MZL, MCL) PTCL Non-neoplastic Hyperplasias Neoplastic HCL Hepatosplenic TCL LGL T-PLL Acute leukemias Myeloproliferative disorders and other myeloid disorders CLL/SLL (rare) LPL (rare) SMZL (rare) Non-neoplastic Hemolytic anemias Non-specific congestion Extramedullary hematopoiesis Storage diseases FOCAL * OR VARIABLE Neoplastic Hodgkin's lymphoma DLBCL FDCT Other dendritic cell tumors Mast cell disease Vascular tumors** Metastases Non-neoplastic IPT Hamartoma Cysts Peliosis *Focal lesion may have considerable overlap with both red and/or white pulp involvement. At times, this division may be arbitrary. **Diffuse involvement is seen in systemic angiomatosis as well as a proportion of cases of littoral cell angioma. Abbreviations: HCL – hairy cell leukemia; TCL – T cell lymphoma; LGL - Large granular lymphocytic leukemia; T-PLL – T cell prolymphocytic leukemia; CLL/SLL – B cell chronic lymphocytic leukemia/small lymphocytic lymphoma; LPL – lymphoplasmacytic leukemia/lymphoma; SMZL – splenic marginal zone lymphoma; MZL – other marginal zone lymphoma; MCL – mantle cell lymphoma; PTCL – peripheral T cell lymphoma; DLBCL – diffuse large B cell lymphoma; FDCT – follicular dendritic cell tumor; IPT – inflammatory pseudotumor. References W orld Health Organization Classification of tumors, Tumors of Haematopoietic and Lymphoid Tissues. Jaffe, E.S., Harris, N.L., Stein, H., Vardiman, J.W. eds. IARC Press, Lyon , France , 2001, pp.103-104. Neiman, RS and Orazi, A: Disorders of the Spleen. 2nd Edition. WB Saunders, Philadelphia , PA , 1999. Wilkins, BS and Wright, DH: Illustrated Pathology of the Spleen. Cambridge University Press, Cambridge, England , 2000. Warnke, RA, Weiss, LM, Chan, JKC, Cleary, ML, Dorfman, RF: Tumors of the Lymph Nodes and Spleen. Atlas of Tumor Pathology, Third Series, Fascicle 14. Armed Forces Institute of Pathology, Bethesda, MD , 1995. Burke JS: Diagnosis of lymphoma and lymphoid proliferations in the spleen. In Jaffe ES (Ed): Surgical Pathology of the Lymph Nodes and Related Organs, 2nd edition, p 448. Philadelphia , WB Saunders, 1995.