Incidental Detection of Radiotracer Uptake in Spindle Cell Lipoma on 18F-PSMA PET/CT

Abstract

An 84-year-old man underwent 18F–prostate-specific membrane antigen (PSMA) PET/CT for staging of a newly diagnosed prostate adenocarcinoma. PET/CT revealed high 18F-PSMA uptake in a thigh mass, which was initially suspected for a metastasis. Histopathology revealed a rare entity of spindle cell lipoma, which should be added to the reported list of neoplasms that can show “false-positive” PSMA uptake during evaluation of patients with prostate carcinoma representing a potential interpretative pitfall.

PSMA-Avid Desmoid Tumor of the Abdominal Wall on 18F-Piflufolastat PET/CT

“…6 There are multiple case reports showing PSMA uptake in benign tumors and nonprostate malignancies. [7][8][9][10][11][12][13] Desmoid-type fibromatosis, also known as aggressive fibromatosis, musculoaponeurotic fibromatosis, and desmoid tumor, is a rare mesenchymal neoplasm associated with high rates of local recurrence but lacks the potential to metastasize. 14 The treatment consensus has changed over the past decade from surgery to observation, and hence imaging plays an important role in follow-up.…”

“…PSMA is also expressed in several other malignancies including breast, lung, colorectal, bladder, renal, pancreatic, and primary brain tumors 6. There are multiple case reports showing PSMA uptake in benign tumors and nonprostate malignancies [7][8][9][10][11][12][13]. Desmoid-type fibromatosis, also known as aggressive fibromatosis, musculoaponeurotic fibromatosis, and desmoid tumor, is a rare mesenchymal neoplasm associated with high rates of local recurrence but lacks the potential to metastasize 14.…”