Incidental Finding of Spindle Cell Sarcoma on 68 Ga-PSMA-11 PET/CT.

Area of Science:

• Nuclear Medicine
• Oncology
• Radiology

Background:

• Prostate-specific membrane antigen (PSMA) PET/CT imaging is crucial for detecting prostate cancer recurrence.
• Gallium-68 prostate-specific membrane antigen-11 (68Ga-PSMA-11) is a widely used radiotracer for this purpose.

Observation:

• A 78-year-old man with biochemical recurrence of prostate adenocarcinoma underwent 68Ga-PSMA-11 PET/CT.
• The scan revealed expected PSMA-avid local recurrence and nodal metastasis.
• An incidental, mildly avid subcutaneous lesion in the right flank was also noted.

Findings:

• Histopathology of the flank lesion confirmed high-grade spindle cell sarcoma.
• This finding represents a rare false positive or atypical presentation for 68Ga-PSMA-11 PET/CT.
• The sarcoma demonstrated mild PSMA avidity, mimicking metastatic disease.

Implications:

• Mildly avid, atypical soft tissue lesions on 68Ga-PSMA-11 PET/CT may represent non-prostate cancer pathology.
• Biopsy is essential for accurate diagnosis and appropriate treatment planning in such cases.
• Awareness of this potential pitfall can prevent misdiagnosis and guide patient management.