Israel Medical Association Journal

Autoimmune diseases constitute a diverse group of disorders characterized by cellular and humoral responses against self. The humoral autoimmune responses are directed against various cellular and extracellular components. These responses are highly specific for each autoimmune disease and result in the production of autoantibodies that characterize certain disease entities, representing a valuable tool for the diagnosis of autoimmune diseases. Furthermore, certain autoantibodies are helpful in the prognosis of disease development, progression and severity, as well as in the classification of patients with distinct disease subtypes. Today, the value of autoantibodies in the follow-up of patients is limited, but preliminary data suggest that they may be useful in predicting response to treatment. 

Antiphospholipid syndrome (APS) is an autoimmune systemic disease characterized by vascular thrombosis (arterial or venous) and/or pregnancy complications associated with the occurrence of autoantibodies, specifically lupus anticoagulant, anticardiolipin antibodies, and/or anti-β2 glycoprotein-I antibodies confirmed at least twice over a 12 week period according to the 2006 Sydney criteria. Antiphospholipid antibodies are encountered  in the general population with a reported prevalence of 1% to 5%  However, APS is far more infrequent with a prevalence of 40–50/100,000 persons and an incidence of about 5 new patients/100,000 persons. APS can be diagnosed in patients with no apparent clinical or laboratory pathology (primary APS) or it may be related to numerous other conditions, autoimmune diseases (usually systemic lupus erythematosus), malignancies, infections and drugs (secondary APS). Women are at risk for APS since the disease is encountered in both the primary and the secondary state in females more often than in men. In addition, women in their reproductive years can develop APS (either classical or obstetric), and special attention is warranted in pregnant women with a diagnosis of APS. The benefits of hormonal therapy in the form of contraception or hormone replacement treatment should be carefully weighed against the increased risk for vascular complications in women with APS.

Background: Despite the lack of clinical studies supporting the use of routine surveillance FDG-positron emission tomography (PET) in patients with diffuse large B cell lymphoma (DLBCL) who achieved remission, many centers still use this strategy, especially in high risk patients. Surveillance FDG-PET computed tomography (CT) is associated with a high false positive (FP) rate in DLBCL patients. 

Objectives: To investigate whether use of specific CT measurements could improve the positive predictive value (PPV) of surveillance FDG-PET/CT. 

Methods: This retrospective study included DLBCL patients treated with CHOP or R-CHOP who achieved complete remission and had at least one positive surveillance PET. CT-derived features of PET-positive sites, including long and short diameters and presence of calcification and fatty hilum within lymph nodes, were assessed. Relapse was confirmed by biopsy or consecutive imaging. The FP rate and PPV of surveillance PET evaluated with/without CT-derived measurements were compared. 

Results: Seventy surveillance FDG-PET/CT scans performed in 53 patients were interpreted as positive for relapse. Of these studies 25 (36%) were defined as true-positive (TP) and 45 (64%) as FP. Multivariate analysis found long or short axis measuring ≥ 1.5 and ≥ 1.0 cm, respectively, in PET-positive sites, International Prognostic Index (IPI) ≥ 2, lack of prior rituximab therapy and FDG uptake in a previously involved site, to be independent predictors of true positive surveillance PET (odds ratio 5.4, 6.89, 6.6, 4.9, P < 0.05 for all). 

Conclusion: PPV of surveillance PET/CT may be improved by its use in selected high risk DLBCL patients and combined assessment of PET and CT findings.