Pigmented villous nodular synovitis mimicking metastatic melanoma on PET-CT.

INTRODUCTION

Positron Emission Tomography - Computed Tomography (PET-CT) is routinely utilized in the management of melanoma, either as a part of staging workup or during surveillance. Since melanomas have a high metastatic potential, any FDG avid lesion is considered suspicious for recurrence. We report a case of a FDG avid lesion, diagnosed during melanoma surveillance, its management and review of literature.

PRESENTATION OF CASE: A 58 year-old-male underwent wide local excision for melanoma of the left cheek, and one year post-operatively a PET-CT that revealed a hypermetabolic focus in his right subscapularis muscle, which upon resection was diagnosed as Pigmented Villonodular Synovitis (PVNS).

DISCUSSION: PVNS is a rare benign giant cell tumor that requires no additional treatment in asymptomatic individuals. PET-CT is used for staging and surveillance of numerous malignancies, including melanoma. A hypermetabolic lesion on a PET-CT scan in the setting of malignancy is always suspicious for recurrence.

CONCLUSION

The surgeon is reminded of a uncommon benign FDG avid lesion. Typical location, nonspecific symptoms and characteristic imaging findings help cue in the diagnosis of PVNS and a tissue diagnosis will establish the diagnosis, thus avoiding unnecessarily aggressive surgical management.