Elevated carbohydrate antigen 19-9 (CA 19-9) in patients with Echinococcusinfection

The carbohydrate antigen 19-9 (CA 19-9), a determinant (sialylated lacto-N- fucopentaose 119) of a circulating oligosaccharide antigen, is a frequently used tumor marker. Echinococcus spp. infects humans throughout the world a nd may be able to synthesize closely related molecules which could interfer e with the measurement and interpretation of CA 19-9 concentration. The mai n objective of the present study was to determine the range of CA 19-9 leve ls in the sera of patients infected by E. granulosus (cystic hydatide disea se; CYSHD) or E. multilocularis (alveolar hydatide disease; ALVHD). Serum samples were collected from patients (aged 10-85 years) over a period of 5 years: from 19 patients with CYSHD and from 20 patients with ALVHD. I nfection was confirmed by positive Echinococcus serology and clinical evide nce provided by imaging and/or histopathological findings. CA 19-9 was detectable in 13 patients with CYSHD (13.5 +/- 8.5 kU/l) and 13 patients with ALVHD (30.0 +/- 21 kU/l; p < 0.05). Thus ALVHD patients exhi bited a significantly higher plasma level of CA 19-9 than CYSHD patients. T he serum level of CA 19-9 assessed with an increased cut-off value (> 22 kU /l) was elevated in nine (45%) of 20 ALVHD patients compared to two (11 %) of 19 CYSHD patients (p < 0.05). Sera from patients with Echinococcus multilocularis infection contain subst ances which cross-react with CA 19-9. These substances originate either fro m the parasite or are synthesized by the host in response to the infection, and possibly bear the Lewis-a antigen or closely related structures which are recognized by anti-CA 19-9 antibodies. Our findings are relevant to the investigation of patients presenting with cystic lesions for which the dif ferential diagnosis includes an infectious or neoplastic origin.