Objective: To report an unusual case of clinical antiphospholipid syndrome seen with recurrent fetal loss, chronic thrombocytopenia, and recurrent idiopathic thrombocytopenic purpura, in which the only laboratory marker was M5-type antimitochondrial autoantibodies (AMA).
Design: Case report.
Setting: University general hospital, tertiary level of clinical care. Institutional practice.
Patient(s): A 65-year-old woman with antiphospholipid syndrome associated with autoimmune polyglandular syndrome of IIIC type.
Intervention(s): Clinical history and biochemical and immunologic markers.
Main outcome measure(s): The presence of M5-type AMA in clinical antiphospholipid syndrome isolated by indirect immunofluorescence.
Result(s): During the 10-year follow-up, immunologic studies detected a persistent positive M5-type AMA at high titer (1/640), antithyroid antibodies, anti-gastric parietal cells, and anti-intrinsic factor. Antinuclear, anti-DNA, and antiphospholipid (anticardiolipin, anti-beta(2)-glycoprotein I) autoantibody tests were all repeatedly negative. Results of coagulation studies and negative lupus anticoagulant were normal on several occasions.
Conclusion(s): Our findings suggest the necessity of determining M5-type AMA in the study panel of antiphospholipid syndrome diagnosis, particularly in the absence of other typical autoantibodies.