68Ga-DOTA-FAPI-04 PET/CT in Erdheim-Chester Disease.

ABSTRACT A 56-year-old woman presented with edema in the upper part of the body, enlarged axillary lymph nodes, and progressive bone pain for 1 year. Malignant disease was initially suspected. This patient underwent 68Ga-DOTA-FAPI-04 PET/CT for detection of the primary lesion and evaluation of disease extent. 68Ga-DOTA-FAPI-04 PET/CT revealed multiple abnormal foci at the skeleton, muscle, lymph nodes, and subcutaneous fat. The imaging findings, highly suggestive of Erdheim-Chester disease, have been later confirmed by histopathology. This case highlights that 68Ga-DOTA-FAPI-04 PET/CT would be useful for evaluating the disease extent, guiding biopsies, and gauging the treatment response in patients with Erdheim-Chester disease.