We report two cases of primary cold agglutinin disease (CAD) associated with megaloblastic anemia in Japanese elderly patients. Case 1 was a 67-year-old male and Case 2 was a 55-year-old male. Both patients were diagnosed with primary CAD, with continuously high cold agglutinin titers (1 : >8,192 and 1 : 16,834, resp.), monoclonal IgM-kappa light chains, and no underlying disease. In addition, both patients had megaloblastic anemia due to vitamin B12 deficiency. One patient received rituximab and both received vitamin 12 supplementation. To date, no cooccurrence of primary CAD and megaloblastic anemia has been emphasized. Thus, the association of these hematological diseases may be incidental; however, given that CAD is an autoimmune disease which may show antibodies against intrinsic factor and gastric parietal cells, this association was thought to be probably not a coincidence. Clinicians should be aware of the possible simultaneous presence of autoimmune hemolytic/megaloblastic anemia in patients with primary CAD.

The authors state that they have no Conflict of Interest (COI).

Background Among various anaphylactic conditions resulting in acute abdomen, mast cell activation disorders, although rare, are included in the differential diagnosis. Case presentation This report describes a 63-year-old Caucasian man who was brought to the emergency room with sudden onset abdominal pain, vomiting, and diarrhea, with breathing difficulty, and with facial swelling after quarrelling with an acquaintance. Computed tomography showed edematous and swollen intestines, consistent with splenomegaly. Physical findings included maculopapular cutaneous mastocytosis. He also had a long history of repeated episodes of anaphylaxis requiring occasional epinephrine auto-injector administration; however, the precise cause of anaphylaxis was previously undetermined. Blood tests showed high serum concentrations of soluble IL-2R and tryptase, suggesting mast cell-related disease. Subsequent biopsies of his bone marrow and cutaneous rash confirmed the diagnosis of systemic mastocytosis (SM). Conclusion SM was diagnosed in a patient with acute abdomen who visited the emergency room.