Objective: To report the clinical and pathologic features of sarcomatous transformation of the skull with involvement of the orbit, in Paget's disease.
Design: Interventional case report.
Participant: An 83-year-old woman with Paget's disease who experienced progressive proptosis of the left eye.
Intervention: Fine-needle aspiration biopsy of the orbital mass.
Results: Cytologic examination revealed round to oval malignant cells with wispy cytoplasm, consistent with the diagnosis of sarcoma. The patient died shortly after institution of orbital radiation therapy and systemic steroid therapy.
Conclusions: Proptosis related to Paget's disease is uncommon, and only rarely is it a result of sarcomatous transformation. Sarcomatous transformation of the skull involving the orbit should be included in the differential diagnosis of progressive proptosis in patients with Paget's disease.