Cold Agglutinin Disease (CAD)

Cold agglutinin disease (CAD) is a rare condition that is found in association with 15% of cases of autoimmune hemolytic anemia (AIHA).1 In the conventional classification, CAD comprises 2 types: primary (idiopathic) CAD and secondary CAD. Primary CAD is not related to any underlying disease, whereas secondary CAD occurs in association with malignant diseases, mainly lymphomas or other cancers, or with acute infections  and autoimmune disorders such as systemic lupus erythematosus (SLE) and rheumatoid arthritis.2,3 Secondary CAD can be characterized by the presence of either monoclonal or polyclonal cold-reacting autoantibodies.4

Underlying Malignancy

The causes of monoclonal secondary CAD are Waldenström macroglobulinemia, lymphomas, chronic lymphoid leukemia, myeloma, and nonhematologic neoplasms.3

The probability that a case of cold agglutinin-mediated AIHA is caused by an underlying malignancy depends on the age of the patient and the extent to which the case is evaluated. Lymphoid (B-cell or plasma cell) malignancies like aggressive non-Hodgkin lymphoma and Waldenström macroglobulinemia occur more frequently in older patients (>60 years) than in younger individuals.2 The association of CAD with plasma cell, B-cell, or lymphoproliferative diseases has been documented in various studies. In a study conducted in 1982 of 78 patients (average age, >60 years) with persistent cold agglutinins, associated lymphoid malignancies were identified in approximately 65%, including lymphomas in 40%, Waldenström macroglobulinemia in 17%, and chronic lymphocytic leukemia (CLL) in 8%.5 In a case series performed in 2013 of 89 patients with CAD (median age, 65 years), lymphoid disorders were noted in approximately 78%, including monoclonal gammopathy of undetermined significance (MGUS) in 61%, other lymphomas in 12%, unspecified lymphoproliferative disorders in 12%, macroglobulinemia in 9%, and CLL in 6%.1 

Biopsy: Bone Marrow and Lymph Node

Bone marrow aspiration and biopsy are recommended to exclude the presence of an underlying hematolymphoid disease. Flow cytometry studies of bone marrow samples are useful to confirm the presence of an abnormal monoclonal lymphoid population. A lymph node biopsy is also required in cases of unexplained lymphadenopathy. This is preferred to fine-needle aspiration because preservation of the nodal architecture is crucial for an accurate diagnosis.6 The bone marrow and lymph node findings of patients with CAD depend on the underlying precipitating disease. A malignant lymphoproliferative disorder can be diagnosed in biopsy specmens.7

Biopsy Findings in Primary Cold Agglutinin-Associated Lymphoproliferative Disorder

An extensive study was carried out on bone marrow aspiration and biopsy samples from 54 patients with CAD. Standard morphological, immunohistochemical, flow cytometric, and molecular methods were used, with reassessment by pathologists specializing in the diagnosis of lymphoma. The observations were consistent with a homogeneous bone marrow disease called primary cold agglutinin (CA)-associated lymphoproliferative disorder (LPD.) The findings were found not to be similar to those of lymphoplasmacytic lymphoma)/Waldenström macroglobulinemia, marginal zone lymphoma, or other known lymphoma entities. Nodular B-cell aggregates were observed in the bone marrow biopsy samples of 40 of 54 patients with CA-associated LPD. The median lymphoid infiltration was 10% of the intertrabecular surface, with a range of 5% to 80%. The specimens of the remaining 14 patients showed only scattered B cells. The infiltration resembled that of marginal zone lymphoma, with no clear immunophenotype. Mature plasma cells were identified throughout between nodular lymphoid aggregates and surrounding the lymphoid aggregates; normally, few plasma cells are found between nodular lymphoid aggregates. The plasma cells exhibited plasmacytoid differentiation of the B-cell clone, with heavy- and light-chain restriction similar to that of the B cells. Biopsy findings characteristic of lymphoplasmacytic lymphoma (LPL), including a lymphoplasmacytoid appearance of the cells, fibrosis, paratrabecular growth, and an increased number of mast cells surrounding the lymphoid aggregates, were absent. The dissimilarities between LPL and CAD were confirmed by flow cytometry and immunohistochemistry. Patients in the study did not have features of extramedullary marginal zone lymphoma, so bone marrow involvement by marginal zone lymphoma was easily excluded. The findings typical of B-cell types of non-Hodgkin lymphoma as recognized by the World Health Organization (WHO) classification of tumors of lymphoid tissues also were not found in cases of CA-associated LPD. Therefore, it must be categorized as a separate entity.8,9


  1. Swiecicki PL, Hegerova LT, Gertz MA. Cold agglutinin disease. Blood. 2013;122(7):1114-1121. doi:10.1182/blood-2013-02-474437
  2. Brugnara C, Berentsen S. Cold agglutinin disease. UpToDate. Updated April 22, 2021. Accessed September 18, 2021. 
  3. Aljubran SA. Cold agglutinin disease. Medscape. Updated August 23, 2021. Accessed September 18, 2021.
  4. Berentsen S, Ulvestad E, Langholm R, et al. Primary chronic cold agglutinin disease: a population based clinical study of 86 patients. Haematologica. 2006;91(4):460-466.
  5. Crisp D, Pruzanski W. B-cell neoplasms with homogeneous cold-reacting antibodies (cold agglutinins). Am J Med. 1982;72(6):915-922. doi:10.1016/0002-9343(82)90852-x
  6. Barcellini W, Giannotta J, Fattizzo B. Autoimmune hemolytic anemia in adults: primary risk factors and diagnostic procedures. Expert Rev Hematol. 2020;13(6):585-597. doi:10.1080/17474086.2020.1754791
  7. Aljubran SA. Cold agglutinin disease workup. Medscape. Updated August 23, 2021. Accessed September 18, 2021.
  8. Berentsen S. Cold agglutinin disease. Hematology Am Soc Hematol Educ Program. 2016;2016(1):226-231. doi:10.1182/asheducation-2016.1.226
  9. Berentsen S, Malecka A, Randen U, Tjønnfjord GE. Cold agglutinin disease: where do we stand, and where are we going?. Clin Adv Hematol Oncol. 2020;18(1):35-44

Reviewed by Kyle Habet, MD, on 9/24/2021.