Cholangiocarcinoma Presenting with Bone and Skeletal Muscle Metastases Mimicking a Relapse of Adult-Onset Still’s Disease: A Case Report

Adult-onset Still’s disease (AOSD) is a rare systemic autoinflammatory disorder. The diagnosis relies on clinico-biological criteria after exclusion of infectious, autoimmune, and neoplastic causes. We report the exceptional case of a 37-year-old man initially managed for typical AOSD with a favorable response to corticosteroids and methotrexate. One year after diagnosis, the occurrence of an atypical inflammatory relapse, associated with deterioration of the general condition, led to the diagnosis of metastatic cholangiocarcinoma. This observation highlights the rare and original nature of this association and emphasizes that any atypical relapse of AOSD should prompt systematic investigation for an emerging condition, particularly of neoplastic origin.