Atypical Imaging Features of Primary Peritoneal High-Grade Serous Carcinoma

A 57-year-old woman presented with fever was incidentally found to have a large hepatogastric space mass with coarse calcifications on CT, accompanied by a markedly elevated serum CA-125 level (3082 U/mL). 18F-FDG PET/MR revealed intense metabolic activity (SUVmax= 10.82) and restricted diffusion without ascites, while both ovaries appeared unremarkable. Pathology confirmed primary peritoneal high-grade serous carcinoma (PPHGSC). This case illustrates atypical imaging features of this rare malignancy, including lesion localization, coarse calcification, and absence of ascites.