(P 032) PLEURAL RELAPSE OF OSTEOSARCOMA AFTER TALC PLEURODESIS

Objective: Pleurodesis is the intentional introduction of a sclerosing agent such as talc, tetracycline derivatives, or chemotherapy to cause inflammation of the visceral and parietal surfaces of the lung, inducing adherence and closure of refractory pneumothorax or broncho-pleural fistula. PLE has been studied since the 1980s in adults. Doxorubicin for malignant effusion has shown up to 72% efficacy (Pamela et al., 1994). Talc (90%) are safe and effective for their irritative activity on the pleura to induce pleural adhesion that scar down the pleural cavity and prevent reoccurrence, however only DOX helps tumoricidal effect.
We describe a case of a young, female patient with osteosarcoma who had a post-surgical refractory pneumothorax from a broncho-pleural fistula that required pleurodesis. The issue was whether DOX or talc should be used as the sclerosing agent, given that her OST had proved to be sensitive to DOX. Because there is no data for using DOX PLE in children, it was not approved, and talc was used. The patient had a large relapse in the previously uninvolved area of the PLE, despite responding to systemic therapy elsewhere.

Methods: A literature review was conducted on PubMed and Google Scholar using the keywords “doxorubicin pleurodesis in children”, “tumor relapse after pleurodesis”, “talc pleurodesis in children”, and “doxorubicin pleurodesis in osteosarcoma”.

Results: Case Report:
At the age of 10, the patient presented with localized OST of the left distal femur. She was treated with 2 cycles of cisplatin, doxorubicin, and methotrexate prior to surgery. At 3 months, the tumor showed 99% necrosis. After a recurrence in her lungs, she had microwave ablation of the right upper lobe mass. 6 months later it was complicated by a spontaneous right-sided pneumothorax and broncho-pleural fistula (Figure 1).
She underwent a successful fistula resection with talc PLE. Pathology showed a subpleural circumscribed nodule of necrotic tissue associated with past thermal ablation with no evidence of a viable OST. 10 months later the patient experienced a relapse in the extra-pleural space. The new mass did not respond to the systemic therapy as the other metastatic sites did, suggesting it was a sequestered space. As the mass grew, it caused significant disability (inability to write, hold a pen, or flex her arm), as well as pain and damage to the brachial plexus. Eventually she was treated with an experimental radioactive micro-sphere technique to kill the majority of the mass, however her disability remains today.

We found no cases of DOX PLE being used in children. We identified one similar case, in which a 13-year-old girl with OST had a spontaneous pneumothorax. The authors hypothesized that a valve mechanism from intermittent bronchiolar obstruction by tumor was responsible for the pneumothorax, as the lesion was at an early stage in the development of macroscopic cysts (Matsurra et al., 2020). We believe that something similar may have occurred in our case. The early development of macroscopic disease from microscopic disease could have been prevented with doxorubicin, a drug the tumor was sensitive to in the past.

Conclusion: The use of DOX for PLE in children is not yet reported. The reoccurrence of the OST may have been prevented using an active agent like DOX instead of the inert talc. We can hypothesize that the entrapped microscopic osteosarcoma cells were able to proliferate the scar tissue created by the talc PLE, and that using doxorubicin instead should be explored in similar situations.