The patient presented with a progressively enlarging, painful mass on the right anterior chest wall. Imaging showed involvement of the sternum and ribs, and histopathological analysis found 90 IgG4-positive plasma cells per high-power field. These findings, together with elevated IgG4, prompted clinicians to consider IgG4-related disease. Prednisone therapy was unsuccessful: the lesion enlarged rapidly, eroded the sternum and ribs, and extended into the anterior mediastinum. The authors also reported no clear epidemiological association with the western Chinese areas where alveolar echinococcosis is primarily distributed.

The diagnostic breakthrough came from metagenomic next-generation sequencing of material aspirated from the lesion. The analysis detected E. multilocularis at a relative abundance of 99.99%, establishing chest-wall alveolar echinococcosis in this patient. In this single case, the infectious lesion mimicked IgG4-related disease both clinically and in tissue examination. The report does not establish a general association between E. multilocularis and IgG4-related disease; it documents the diagnostic overlap encountered in one patient.

Radical resection was precluded by the lesion’s extensive involvement of the sternum, ribs and anterior mediastinum. The patient instead began oral albendazole at 400 mg per day. At two years, the lesion had shrunk from more than 60 millimeters to 17 millimeters, while her symptoms had nearly completely resolved. These observations describe the response in an individual case and are not results from a controlled treatment trial. The authors emphasize long-term follow-up in alveolar echinococcosis because the infection can have a prolonged clinical course and is highly pathogenic.

Analysis of the mitochondrial cytochrome c oxidase subunit 1 gene placed the patient’s E. multilocularis isolate within the Asian mitochondrial lineage, alongside sequences reported from western China. The researchers could not identify the source of infection or connect it to a specific location, animal or exposure. The case therefore documents a confirmed infection in Henan without establishing its epidemiological origin. Its broader significance is diagnostic: in this patient, imaging, histopathology and IgG4 measurements suggested IgG4-related disease, while sequencing of lesion aspirate established an infectious cause, and the observed lesion shrinkage and symptom improvement followed two years of albendazole treatment.

Subject of Research: Diagnosis and two-year treatment outcome of chest-wall alveolar echinococcosis mimicking IgG4-related disease in a single-patient case report.

Article Title: Rare metastatic alveolar echinococcosis of the chest-wall mimicking IgG4-related disease: diagnosis and treatment of the first reported case in Henan Province, China

Article References: Wang, X., Zhang, Y.-L., Wang, W., Zhang, X.-F., Zhang, W.-B., Chen, W.-Q., & Han, S. (2026). Rare metastatic alveolar echinococcosis of the chest-wall mimicking IgG4-related disease: diagnosis and treatment of the first reported case in Henan Province, China. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14650-3

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14650-3

Keywords: alveolar echinococcosis, Echinococcus multilocularis, chest-wall lesion, IgG4-related disease, metagenomic sequencing, albendazole, Henan Province, case report, parasite genomics, Rare, metastatic, alveolar