# A Novel Case of Tenosynovial Giant Cell Tumor at 4 Years After Total Knee Arthroplasty for Medial Osteoarthritis With Synovial Osteochondromatosis

## TL;DR

A rare case of tenosynovial giant cell tumor developed four years after knee replacement surgery in a patient with synovial osteochondromatosis.

## Contribution

This is the first reported case of de novo tenosynovial giant cell tumor occurring after total knee arthroplasty in the context of synovial osteochondromatosis.

## Key findings

- A 72-year-old woman developed persistent right knee pain and hemarthrosis four years after TKA.
- Histologic analysis confirmed the presence of tenosynovial giant cell tumor in the synovial tissue.
- The case highlights the possibility of TGCT arising in the setting of synovial osteochondromatosis post-TKA.

## Abstract

We report an unusual case of a tenosynovial giant cell tumor (TGCT) in a patient who received a total knee arthroplasty (TKA) for medial knee osteoarthritis with synovial osteochondromatosis (SO). A 72-year-old woman underwent conventional jig-based simultaneous bilateral bicruciate-stabilized TKA. Four years after the surgery, she came to our hospital with a chief complaint of persistent pain in the right knee only, with recurrent spontaneous hemarthrosis. We performed a synovectomy with open excisional debridement and a polyethylene exchange. Histologic analysis of synovial samples was consistent with TGCT. We present the imaging and pathological details of the first case of de novo TGCT that occurred in the background of SO after TKA.