Echinococcosis, especially alveolar echinococcosis (AE), is becoming an emerging/re-emerging disease with a growing number of cases reported globally. The diagnosis of echinococcosis is based mainly on imaging, which may be challenging when the image presentation is atypical. We reported one patient with suspected cystic echinococcosis (CE) by imaging. The cell-free DNA (cfDNA) obtained from sequencing the patient's plasma before the operation showed that this patient probably had AE with 45 reads mapped to the Echinococcus multilocularis reference genome (Read-Pairs Per Million = 0.24). The patients underwent surgery, and the pathological result showed that the patient had AE. The conventional polymerase chain reaction (PCR) of her lesion sample extraction also indicated that the infection was caused by Echinococcus multilocularis. The follow-up ultrasound after three months indicated no recurrence. We demonstrated that the differentiation of CE and AE by imaging may not be that easy, with further elaboration on the differentiation between AE and CE in different aspects. We demonstrated that it is possible to use patients' plasma cfDNA mapped to Echinococcus references before the operation to obtain the objective clue of the lesion to facilitate diagnosis.
Keywords: Echinococcus granulosus sensu lato; Echinococcus multilocularis; alveolar echinococcosis; cell-free DNA; cfDNA; cystic echinococcosis; misdiagnosis.