C1-C2 pigmented villonodular synovitis and clear cell carcinoma: unexpected presentation of a rare disease and a review of the literature.

INTRODUCTION: Pigmented Villonodular synovitis (PVNS) is a rare vertebral pathology--around 50 reports, only 3 concerning C1-C2 location. CASE REPORT: A 64-year-old man, submitted to a right nephrectomy for a clear cell carcinoma, presented with an asymptomatic osteolytic C1-C2 lesion. Even though the diagnosis of metastatic disease was the most probable, the presence of a solitary lesion without other osseous or systemic localization and the predicted low risk of recurrence imposed a surgical biopsy. A pigmented villonodular synovitis diagnosis was made, a rare vertebral pathology--around 50 reports, only 3 concerning C1-C2 location. No further treatment was assigned precluding the iatrogenic consequences of empirical treatments based on clinical diagnosis with no histopathological support. The patient remains stable at 18 months of follow-up.
CONCLUSION: A large differential diagnosis should be made when the typical findings for metastatic disease are absent precluding the iatrogenic consequences of empirical treatments based on clinical diagnosis with no histopathological support.