Splenic micro-anatomical localization of small lymphocytic lymphoma/chronic lymphocytic leukemia using a novel combined silver nitrate and immunoperoxidase technique

Analysis of subendothelial leukocyte infiltration in the trabecular veins of septic spleen

The splenic white pulp (WP) consists of CD20-positive lymph follicles (LFs) and CD3-positive periarteriolar lymphoid sheaths. Atrophy of the WP associated with a prolonged period of sepsis is a well-known pathological finding at autopsy. On the other hand, dense subendothelial leukocyte infiltration in the trabecular veins is also commonly observed in autopsy specimens of septic spleen. However, the characteristics and significance of this finding have not yet been well studied. In this study, autopsy spleens obtained from 55 sepsis and 45 non-sepsis patients were compared to determine the clinicopathological characteristics of subendothelial leukocyte infiltration in the trabecular veins, and its pathological significance was discussed. Severe and mild subendothelial leukocyte infiltration in the trabecular veins was observed in 45.5% of sepsis patients, but was absent in non-sepsis patients. Several clinicopathological characteristics of subendothelial leukocyte infiltration were identified. Firstly, the majority of infiltrated cells were lymphocytes. Secondly, both incidence and degree of infiltration were decreased at the late phase of sepsis accompanied by atrophy of the WP. Thirdly, types and compositions of infiltrated leukocytes reflected the histological findings of the spleen. Thus, the percentage of CD20-positive cells in the infiltrating cells into the subendothelium was proportional to the relative size of the CD20-positive area in the specimen, and the percentage of MUM1-p-positive cells in the infiltrating cells was proportional to the frequency of appearance of MUM1-p-positive cells in the red pulp. The CD20-positive area approximated the relative size of the WP in the septic cases, while the frequency of appearance of MUM1-p-positive cells was indicative of the differentiation levels of LFs into plasma cells upon antigen stimulation. Lastly, the intense subendothelial infiltration of CD20-positive cells was specific for the early stage of sepsis, and the morphological characteristics of these CD20-positive cells suggested their association with the marginal zone. Based on these clinicopathological characteristics and the fact that leukocyte infiltration into the subendothelium of trabecular veins became undetectable as atrophy of the WP progressed, it was suggested that the infiltrating cells had migrated from the WP, and this cell infiltration is an early activated immunological reaction in the spleen. Furthermore, the presence of possible efflux or drainage routes in the subendothelial spaces of trabecular veins was suggested.

Pathology of chronic lymphocytic leukemia: an update

Chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) is a clonal lymphoproliferative disorder characterized by proliferation of morphologically and immunophenotypically mature lymphocytes. CLL/SLL may proceed through different phases: an early phase in which tumor cells are predominantly small in size, with a low proliferation rate and prolonged cell survival, and a transformation phase with the frequent occurrence of extramedullary proliferation and an increase in large, immature cells. Although some patients with CLL have an indolent disease course and die after many years of unrelated causes, others have very rapidly disease progression and die of the disease within a few years of the diagnosis. In the past few years, considerable progress has been made in our ability to diagnose and classify CLL accurately. Through cytogenetics and molecular biology, it has been shown that CLL and variants are associated with a unique genotypic profile and that these genetic lesions often have a direct bearing on the pathogenesis and prognosis of the disease. Similarly, the development of antibodies to new biologic markers has allowed the identification of a unique immunophenotypic profile for CLL and variants. Moreover, accumulating evidence suggests that CLL cells respond to selected microenvironmental signals and that this confers a growth advantage and an extended survival to CLL cells. In this article, we will review the progress in the pathobiology of CLL and give an update on prognostic markers and tools in current pathology practice for risk stratification of CLL.

Splenic histology and histopathology: an update

The spleen can be a troublesome specimen for the surgical pathologist, not only because experience with the range of "normal" splenic histology is limited by its rarity but also because there is an often a frustrating discordance between the patient's clinical condition and the perceived findings. Patients with a dramatic clinical presentation that points to splenic pathology ("hypersplenism" or marked splenomegaly) not infrequently have no discernable or have barely perceptible histologic abnormalities of the spleen. Similarly, patients whose spleens contain histologic findings that seem to deviate significantly from the "norm" (histiocytic proliferations, vasoformative lesions, stromal hyperplasia) may have no clinically detectable hematologic complaints. For most pathologists, the frame of reference for normal splenic histomorphology derives largely from experience with autopsy spleens and spleens removed for trauma or immune thrombocytopenia. These are all settings in which pre-existing disease, the immune status of the patient, and therapy influence the findings and--in cases in which fixation has been delayed--even the ability to make the findings. This review presents practical aspects of splenic development and immunoarchitecture and relates this to the pathologist's approach in evaluating the abnormal spleen and assists in resolving such discordances. Benign conditions that contrast with the subjects of subsequent articles in this issue are emphasized.

Splenectomy influences bone marrow infiltration in patients with splenic marginal zone cell lymphoma with or without villous lymphocytes

BACKGROUND

Splenic marginal zone cell lymphoma (SMZL) is a low grade B-cell lymphoma in which patients can have circulating villous lymphocytes and can show a peculiar intrasinusoidal bone marrow (BM) infiltration. Splenectomy is the reported treatment of choice for these patients. The objective of this study was to evaluate the effects of splenectomy on patients with BM lymphomatous infiltration.

METHODS

BM biopsies of 16 patients with SMZL were studied morphologically and immunohistochemically. In 12 patients, BM biopsies were taken before and after splenectomy. Four patients did not undergo splenectomy, and their BM biopsies were performed with an approximately 1 year interval.

RESULTS

BM infiltration ranged from 10% to 40% of overall cellularity and was mostly of the intrasinusoidal type. After splenectomy, BM infiltration tended to become frankly nodular and showed an increase in tumor burden. Nonsplenectomized patients showed an unmodified picture.

CONCLUSIONS

Splenectomy seems to induce important changes in patients with BM infiltration, probably through the lack of microenvironmental factors on circulating cells. These effects suggest reconsidering the role of splenectomy in the treatment of patients with SMZL.