Not All Rheumatoid Factor-Positive Tests Mean RA

Discussion

AITL is a rare disease that accounts for 1–2% of all non-Hodgkin’s lymphomas and about one in five cases of peripheral T cell lymphomas.⁴ First described in 1974, the disease was named angioimmunoblastic lymphadenopathy with dysproteinemia.^2,4,5 Patients classically presents with B symptoms, as described above, or with a rash (observed in 20–50%), which may include urticarial lesions and nodular tumors.⁴

AITL leads to three pathologically characteristic histological and architectural changes in lymph nodes: extensive alteration of the nodal architecture, abundance of small vessels and polyclonal proliferation of immune reactive cells.⁶

Once considered an aggressive neoplasia that derived from an abnormal immune reaction, genomic studies have since demonstrated AITL to be a clonal rearrangement of T cell receptor genes due to acquired driver genes.^2,7 Follicular T helper cells are the main subset implicated in the pathogenesis of AITL. This subset of T cells resides within the follicles, and their main role is to support B cell survival, proliferation, maturation and migration.³

Several genetic changes have been implicated in the neoplastic transition of T follicular helper cells, such as the G17V mutation of Ras homolog family member A.³ Although this mutation has also been identified in other malignancies, such as diffuse gastric carcinoma and Burkitt lymphoma, it may serve as a non-invasive diagnostic test for AITL in the future.^1,3

Given the immune-activating effects of AITL, the production of detectable levels of rheumatoid factor and the anti-smooth muscle antibody may result in positive autoantibody tests.³

This hematoxylin and eosin (H&E) stain of the retroperitoneal lymph node at 40x magnification demonstrates atypical lymphocytes and numerous plasma cells.

This H&E stain of the retroperitoneal lymph node at
60x magnification demonstrates enlarged and
atypical lymphocytes.