FDG PET/CT AND PSMA PET/CT IN EPITHELIOID SARCOMA STAGING: A CASE REPORT

Abstract

Introduction

Epithelioid sarcoma (ES) is a rare malignant soft-tissue neoplasm characterized by indolent growth, most commonly arising in the distal extremities, with a predilection for the hands and feet. ES poses a clinical diagnostic challenge, as its presentation may mimic benign conditions, particularly inflammatory or granulomatous lesions. ¹8F-FDG PET/CT is used for primary staging of soft tissue sarcomas, including ES. Although no studies have focused on PSMA and ES to date, the Prostate Specific Membrane Antigen (PSMA) may be an alternative for diagnosing and potentially treating these patients due to its Theranostic capabilities. We present a case of epithelioid sarcoma and evaluate the diagnostic performance of ¹8F-PSMA PET/CT compared to ¹8F-FDG PET/CT. Ethical Approval (CAAE: 30476720.9.0000.5404).

Case presentation

A 34-year-old man presented with a lesion on the plantar region of the right foot with progressive growth over 9 months and weight loss. MRI showed a well-defined, lobulated, heterogeneous mass measuring 90 × 71 × 64 mm, with a focus of cystic degeneration, located on the plantar and medial surfaces of the midfoot. Histopathology was consistent with ES. A staging 18F-FDG PET/CT showed marked hypermetabolism in the ES as well as in locoregional lymph node metastases in the right popliteal fossa and peri-bronchial lymph nodes, in lung nodules, and in the distal portion of the tibia. After 24 hours, an 18F-PSMA PET/CT scan was performed. The comparison of 18F-PSMA PET/CT and 18F-FDG PET/CT showed higher PSMA uptake in the ES (SUVPSMA = 24; SUVFDG = 14); similar uptake in popliteal fossae lymph node metastases (SUVPSMA = 9; SUVFDG = 11) and peri-bronchial lymph nodes (SUVPSMA = 7; SUVFDG = 9); lower uptake in lung nodes (SUVPSMA = 3; SUVFDG = 10) and tibia (SUVPSMA = 5; SUVFDG = 15).

Conclusion

This report highlights the potential role of PSMA PET/CT in staging of patients with ES, demonstrating lesion detection comparable to that of FDG PET/CT while also offering a Theranostics perspective.