# Conversion to Complete, Parenchyma-Sparing Resection after Prolonged Denosumab for Bilateral Multifocal Pulmonary Metastases from Giant Cell Tumor of Bone: A Case Report

## TL;DR

A woman with lung metastases from a bone tumor achieved long-term remission after denosumab treatment followed by precise lung surgery.

## Contribution

Demonstrates a surgery-forward strategy using denosumab to enable parenchyma-sparing resection in multifocal pulmonary GCTB.

## Key findings

- Denosumab treatment over 2.5 years led to shrinkage and calcification of lung metastases.
- Staged thoracoscopic resections achieved complete macroscopic clearance with negative margins.
- The patient remains recurrence-free 7 years and 5 months post-surgery.

## Abstract

Giant cell tumor of bone (GCTB) rarely metastasizes, but pulmonary lesions pose therapeutic challenges. We report a woman in her 30s who developed multiple bilateral lung nodules 3.5 years after distal ulna GCTB resection and local recurrences. Denosumab 120 mg every 4 weeks was given for 2.5 years, producing shrinkage, calcification, and stability. Staged, palpation-guided thoracoscopic wedge resections (8 left, 5 right) achieved complete macroscopic clearance with negative margins. Histology showed spindle-cell proliferation with woven bone and depletion of giant cells; H3.3 G34W immunostaining confirmed metastatic GCTB. She remains recurrence-free 7 years and 5 months after metastasectomy. Denosumab displayed site-specific surgical implications—unfavorable at the primary bone site due to peritumoral sclerosis, yet advantageous in the lung where it clarifies margins and enables parenchyma-sparing R0 resection. A surgery-forward strategy that uses time-limited denosumab as a bridge to meticulous thoracoscopic metastasectomy may secure durable control in multifocal pulmonary GCTB.