Ovarian dermoid cyst-associated autoimmune hemolytic anemia: a case report with emphasis on pathogenic mechanisms.

Autoimmune hemolytic anemia (AIHA) as a manifestation of ovarian dermoid cyst (ODC) is a rare paraneoplastic syndrome of unknown pathogenesis. Among mechanisms postulated to explain this association, cross-reactivity between cyst and red blood cell (RBC) antigens, and local production of RBC autoantibodies by intracyst B lymphocytes are the most likely. Studies to test these hypothesis were done in a patient diagnosed of AIHA associated with a nonpalpable ODC, in whom the AIHA subsided after tumor excision. The RBC-bound autoantibody was an IgG directed against the Rh complex. The cyst's fluid content lacked detectable RBC autoantibodies or immunoglobulins, the latter being measured by a high-sensitivity assay. It also failed to inhibit the ability of the purified autoantibody to agglutinate RBCs. Ovarian dermoid cyst histology disclosed that (1) the biotin-labelled RBC autoantibody did not bind to ODC structures; (2) scanty amounts of small mature lymphocytes (50% CD45RO+; 50% CD20+) were present only in a few tissue sections; (3) plasma cells producing IgM or IgG were extremely scarce; and (4) deposits of immunoglobulins were not detected into the ODC. These data fail to support any of the aforementioned hypotheses on the pathogenesis of this paraneoplastic syndrome. Other possible mechanisms are discussed, and a wider use of imaging diagnosis to search for ODC in women with AIHA is emphasized.