Metastasizing tenosynovial giant cell tumour, diffuse type/pigmented villonodular synovitis

Area of Science:

• Orthopedic Oncology
• Pathology
• Radiology

Background:

• Tenosynovial giant cell tumour (TGCT), diffuse type, is a locally aggressive neoplasm.
• It often presents with multiple recurrences.
• Distinguishing it from its rare malignant variant is challenging due to overlapping imaging features.

Observation:

• A 63-year-old male presented with TGCT, diffuse type, of the knee.
• The patient underwent multiple surgical procedures.
• Metastasis to inguinal lymph nodes was observed.

Findings:

• The resected tumour showed no morphologic evidence of sarcomatous transformation.
• Despite the absence of overt malignancy, inguinal lymph node metastases were present.
• This suggests a potential for distant spread in TGCT, diffuse type, even without clear malignant features.

Implications:

• This case challenges the current understanding of TGCT, diffuse type, metastasis.
• It suggests that lymph node involvement may occur without histologic evidence of malignancy.
• Further research is needed to understand the metastatic potential and improve diagnostic criteria for TGCT, diffuse type.