The Histopathology of Cold Agglutinin Disease–Associated B-Cell Lymphoproliferative Disease

Angela Guenther, MD; Anne Tierens, MD, PhD; Agnieszka Malecka, PhD; Jan Delabie, MD, PhD

Am J Clin Pathol. 2023;160(3):229-237.

Abstract and Introduction

Abstract

Objectives: Primary cold agglutinin disease is a type of autoimmune hemolytic anemia caused by circulating antibodies against I antigen, a carbohydrate expressed on most cells, including red blood cells. The underlying disease has been characterized in recent years as a distinct B-cell lymphoproliferative disease of the bone marrow, occurring mostly in the elderly. The disease has been now been included as a separate entity in the most recent classifications of mature B-cell neoplasms.

Methods: A review of the characteristics of cold agglutinin disease is provided, with an emphasis on the pathology features.

Results: A detailed description of the histopathology, immunophenotype, and genetics of cold agglutinin disease is provided and compared to other B-cell lymphoproliferative diseases in the bone marrow with similar features.

Conclusions: Recognition of the pathology features of cold agglutinin disease allows to distinguish it from other diseases, especially lymphoplasmacytic lymphoma and marginal zone lymphoma.

Introduction

Primary cold agglutinin disease is a rare autoimmune hemolytic anemia resulting from a monoclonal circulating antibody—in most cases, IgM and, rarely, IgG or IgA.^[1,2] The incidence of cold agglutinin disease is less than 2/million/year, although the incidence seems higher in northern regions compared with southern regions.^[3] The immunoglobulin light chain associated with the cold agglutinin is IgK and only rarely IgL. The antibody binds I blood group antigen on red blood cells. Transient binding of the antigen occurs only at lower temperatures, at exposed or acral sites of the body—hence the name "cold" agglutinins. The antibody dissociates from the red blood cells at a higher temperature in more central areas of the body. Binding to red blood cells, at a lower temperature, causes complement activation with deposition of complement C3b on the cell membrane. Complement-coated red blood cells are subsequently removed by the Kupffer cells of the liver and, to a lesser degree, by macrophages in the spleen. Cells that are not readily removed carry complement C3d on their surface due to further enzymatic cleavage of C3b. Rarely, full complement activation occurs, resulting in intravascular hemolysis. The antibody typically results in red cell agglutination of blood samples kept at room temperature or a lower temperature, needing warming up of samples prior to analysis. The severity of hemolysis is largely dependent on the thermal amplitude of the antibody, defined as the highest temperature at which it still binds to the red blood cells. Apart from anemia, patients also have Raynaud phenomenon, acrocyanosis, or livedo reticularis; these are cold-induced symptoms with disturbance of the blood circulation. Very rarely, more severe circulatory problems result in skin necrosis.

It has been recognized for some time that patients with cold agglutinin disease have an underlying lymphoproliferative disease.^[4] These disorders were typed as lymphoplasmacytic lymphoma, Waldenström macroglobulinemia, marginal zone lymphoma, or IgM monoclonal gammopathy of unknown significance (MGUS), resulting in the notion that cold agglutinin disease was a syndrome associated with diverse B-cell lymphoma types.^[4,5] More recently, the B-cell lymphoproliferative disease underlying cold agglutinin disease has been better characterized and revealed a homogeneous histology and immunophenotype, with only few cases attributed to other well-known small B-cell lymphoma types.^[3,6] In addition, the genetic and molecular profile is distinct from the other small B-cell lymphomas. Hence, cold agglutinin disease–associated B-cell lymphoproliferative disease has been included in the most recent World Health Organization classification of hematolymphoid tumors as well as in the International Consensus Classification of mature lymphoid neoplasms.^[6,7] The clonal disease does not involve other organs such as lymph nodes or spleen and remains confined to the bone marrow. The term cold agglutinin syndrome is restricted to the rarer cold agglutinin–mediated hemolytic anemia secondary to infection, autoimmune disease, or other malignancy. In this review, the focus is on the pathology features of cold agglutinin disease–associated lymphoproliferative disorder and, especially, the features that distinguish it from lymphoplasmacytic lymphoma with which it may be confused.

1 2 3 4 5 6

Next Section

Table 1. Differential Features of Cold Agglutin Disease, Lymphoplasmacytic Lymphoma, and Marginal Zone Lymphoma
Characteristic	Cold Agglutinin Disease–Associated Lymphoproliferative Disease	Lymphoplasmacytic Lymphoma	Marginal Zone Lymphoma
Histology of the bone marrow	Nodular intraparenchymatous infiltration (usually less than 10% of all cells), absence of intrasinusoidal infiltration	Nodular and/or diffuse intraparenchymatous infiltration, paratrabecular infiltration, limited intrasinusoidal infiltration	Nodular intraparenchymatous infiltration, intrasinusoidal infiltration
Cytologic features	Small lymphoid cells with round nuclei with variably clumped chromatin and without prominent nucleoli. Plasma cells are scant and may be diffusely present with limited concentration around the lymphoid nodules.	Small lymphoid cells, plasmacytic cells, and plasma cells; these cells are intermixed with varying ratios from case to case. Cells have more clumped chromatin, absent prominent nucleoli, and Dutcher inclusions may be seen.	Small lymphoid cells without round or slightly irregular nuclei without clumped chromatin and without prominent nucleoli. Plasma cells may be present or absent. Scattered immunoblasts may be observed.
Immunophenotype
B lymphoid cells	CD5– or CD5+, CD11c–, CD20+, CD23–, CD43–	CD5– or CD5+, CD11c+, CD20+, CD23–, CD43– or CD43+	CD5– or CD5+, CD11c+, CD20+, CD23–, CD43– or CD43+
Plasmacytic B cells	Absent	CD20+, cIgM+, cIgK+, or more rarely cIgG+ or cIgA+ or cIgL+	Absent
Plasma cells	CD20–, CD138+, cIgM+, cIgK+	CD20–, CD138+, cIgM+, cIgK+, or more rarely cIgG+ or cIgA+ or cIgL+	CD20–, CD138+, cIgG+ or cIgA+ or cIgM+, cIgK+ or cIgL+
IGHV gene usage	IGHV4-34 (near 100%)	IGHV3 family genes, most frequently IGHV3-23 and IGHV3-7	IGHV1-2 (SMZL), IGHV3-4 and IGHV4-34(NMZL), and IGHV1-69, IGHV4-34, IGHV3-7, IGHV1-69 according to site of involvement for ENMZL
Gene mutations	KMT2D (over 50%) CARD11 (over 30%) CXCR4 (over 25%)^a	MYD88 (over 90%) CXCR4 (over 30%)^a	SMZL: NOTCH2 (20%), KLF2 (20%) NMZL: NOTCH2 (25%), KLF2 (20%) ENMZL: TNAIP3 (15%)
Cytogenetics	Gains of chromosomes 3, 12, 18	Del 6q	SMZL: deletion of chromosome 7q NMZL: gains of chromosomes 3,12,18 ENMZL: gains of chromosomes 3, 12, 18; t(11:18), t(14:18), t(1:14)
Large cell transformation	Very rare	5%-13%	30%, depending on MZL type

ENMZL, extranodal marginal zone lymphoma; MZL, marginal zone lymphoma; NZML, nodal marginal zone lymphoma; SMZL, splenic marginal zone lymphoma.
^aMutation hotspots in the CXCR4 gene differ between the diseases.

Table 2. Salient Routine Diagnostic Features, When Present, Allowing to Exclude Cold Agglutin Disease From the Differential Diagnosis of Small B-Cell Lymphoid Cell Infiltration in the Marrow
Characteristic	Bone Marrow Histology	B-Cell Immunophenotype	Genetic Analysis	Laboratory Findings	Clinical Findings
Lymphoplasmacytic lymphoma/IgM MGUS	Paratrabecular lymphoid infiltration	—	MYD88 mutation	—	—
Marginal zone lymphoma/MBL with non-CLL immunophenotype	—	—	—	—	Extramedullary involvement (lymphoid tissues, extranodal tissues)
Chronic lymphocytic leukemia/MBL with CLL-like immunophenotype	Interstitial lymphoid infiltration	CD5+, CD23+, CD79b–, CD200bright	—	—	—
Mixed cryoglobulinemia, type II	—	—	—	Monotypic IgM cryoglobulin	—

CLL, chronic lymphocytic leukemia; MBL, monoclonal B lymphocytosis; MGUS, monoclonal gammopathy of unknown significance; —, feature not sufficiently different from cold agglutinin disease for diagnostic purposes. .