68Ga-Prostate-Specific Membrane Antigen Uptake in Gastrointestinal Stromal Tumor

Area of Science:

• Nuclear medicine
• Oncology
• Gastroenterology

Background:

• Prostate-specific membrane antigen (PSMA) Positron Emission Tomography/Computed Tomography (PET/CT) is increasingly used for staging prostate cancer.
• The diagnostic utility of PSMA PET/CT extends beyond prostate cancer, with potential for detecting other malignancies.

Observation:

• A 62-year-old man with newly diagnosed prostate cancer underwent Ga-PSMA PET/CT for staging.
• The scan identified a lesion in the upper abdomen with significant PSMA avidity.
• Histopathology confirmed the lesion as a gastrointestinal stromal tumor (GIST).

Findings:

• The GIST exhibited increased PSMA uptake in its margins and a central photopenic area.
• This imaging pattern is proposed as characteristic for PSMA-avid GISTs.
• The primary staging scan for prostate cancer incidentally detected a GIST.

Implications:

• PSMA PET/CT may reveal unexpected findings, necessitating careful interpretation.
• The characteristic imaging pattern observed could aid in the diagnosis of GISTs.
• This case broadens the understanding of PSMA expression in non-prostate tumors.