Recommendations for gross examination and sampling of surgical specimens of the spleen

CD5-Negative, CD10-Negative Low-Grade B-Cell Lymphoproliferative Disorders of the Spleen

CD5-negative, CD10-negative low-grade B-cell lymphoproliferative disorders (CD5-CD10-LPD) of the spleen comprise a fascinating group of indolent, neoplastic, mature B-cell proliferations that are essential to accurately identify but can be difficult to diagnose. They comprise the majority of B-cell LPDs primary to the spleen, commonly presenting with splenomegaly and co-involvement of peripheral blood and bone marrow, but with little to no involvement of lymph nodes. Splenic marginal zone lymphoma is one of the prototypical, best studied, and most frequently encountered CD5-CD10-LPD of the spleen and typically involves white pulp. In contrast, hairy cell leukemia, another well-studied CD5-CD10-LPD of the spleen, involves red pulp, as do the two less common entities comprising so-called splenic B-cell lymphoma/leukemia unclassifiable: splenic diffuse red pulp small B-cell lymphoma and hairy cell leukemia variant. Although not always encountered in the spleen, lymphoplasmacytic lymphoma, a B-cell lymphoproliferative disorder consisting of a dual population of both clonal B-cells and plasma cells and the frequent presence of the MYD88 L265P mutation, is another CD5-CD10-LPD that can be seen in the spleen. Distinction of these different entities is possible through careful evaluation of morphologic, immunophenotypic, cytogenetic, and molecular features, as well as peripheral blood and bone marrow specimens. A firm understanding of this group of low-grade B-cell lymphoproliferative disorders is necessary for accurate diagnosis leading to optimal patient management.

Association of Preoperative Clinical, Laboratory, Imaging, and Pathologic Data With Clinically Beneficial Pathology Among Routine Splenectomy Specimens

IMPORTANCE

Previous studies have shown that uniform pathologic review of all splenectomy surgical specimens reveals new clinically actionable diagnoses only in a minority of cases.

OBJECTIVE

To examine whether the aggregate of clinical, laboratory, imaging, and pathologic preoperative data is associated with a clinically beneficial pathologic study for routine splenectomy surgical specimens.

DESIGN, SETTING, AND PARTICIPANTS

This single-center retrospective cohort study included all patients who underwent splenectomy from January 1, 2013, through December 31, 2018, at a single center. Clinical, imaging, and pathologic data were extracted from the institution's electronic medical records system. Data analysis was conducted from June to November 2020.

EXPOSURES

Undergoing splenectomy for trauma or diagnostic or therapeutic indications.

MAIN OUTCOMES AND MEASURES

Spleen pathology study resulting in a new medical diagnosis or change in medical management.

RESULTS

Overall, 90 patients (53 [59%] men) with a median (range) age of 59 (19-90) years underwent splenectomy for therapeutic purposes in 41 patients (45%), trauma in 24 patients (27%), diagnostic purposes in 15 patients (17%), and combined therapeutic and diagnostic purposes in 9 patients (10%). In 14 patients (15%) a new malignant neoplasm was found, and in 8 patients (9%), a new nonneoplastic medical condition was diagnosed. A new pathologic diagnosis resulted in change in medical management in 16 patients (18%). In patients without a prior diagnosis of cancer, 41 of 56 pathology biopsies (73%) were found to be normal whereas in 7 biopsies (13%), a new diagnosis of a hematologic malignant neoplasm was revealed (P < .001). Patients with clinical splenomegaly were significantly more likely to have a new pathologic diagnosis of cancer compared with patients without splenomegaly (15 of 26 [58%] vs 4 of 64 [7%]; P < .001). In 39 of 43 patients (91%) with normal presurgery imaging studies, normal spleen pathology was revealed, whereas in 14 of 17 patients (82%) with abnormal imaging studies, a new hematological malignant neoplasm was diagnosed following pathologic review of the spleen specimen (P < .001). Patients with gross abnormalities on macroscopic examination had a significantly increased likelihood of a hematological cancer diagnosis (17 of 40 [43%]) and a solid cancer diagnosis (4 [10%]) compared with patients with grossly normal specimens (4 of 49 [8%]; P < .001).

CONCLUSIONS AND RELEVANCE

In this cohort study, routine pathologic review of spleen specimens was clinically beneficial in patients with splenomegaly, abnormal imaging results, a prior diagnosis of cancer, and with grossly abnormal spleens.

Practical Applications in Immunohistochemistry: An Immunophenotypic Approach to the Spleen

CONTEXT.—

Even though immunohistochemistry is routinely used by pathologists, evaluation of immunohistochemistry in splenic lesions remains difficult for many. Classification of benign and splenic lesions often requires a combination of hematoxylin-eosin evaluation, immunophenotyping, and sometimes molecular testing. Immunohistochemical staining is essential in evaluating many splenic lesions, and requires an understanding of the normal compartments of the spleen.

OBJECTIVE.—

To address different immunohistochemical features used for identification and subclassification of different lesions of the spleen, as well as in the normal compartments of the spleen.

DATA SOURCES.—

The information outlined in this review article is based on our experiences with a variety of spleen cases, on the current World Health Organization classification of hematopoietic and lymphoid tumors, and on a review of English-language articles published during 2018.

CONCLUSIONS.—

Features for phenotyping normal spleen as well as a variety of splenic lesions, including littoral cell angioma and splenic marginal zone lymphoma, are discussed. Suggested immunopanels are provided to assist in the diagnosis of different lesions of the spleen.