Malignant transformation in Paget disease of bone.

BACKGROUND: The previously reported incidence of malignant transformation of Paget disease up to 5.5% and its dismal prognosis have prompted the clinical investigation of a large population with Paget disease.

METHODS: A chart review of symptomatic and asymptomatic patients with a diagnosis of Paget disease between 1970 and 1985 at four large Montreal Hospitals revealed 1078 patients. Eight patients with malignant transformation were studied in detail.

RESULTS: The incidence of malignant transformation was 0.7%, and the most frequent histologic type was osteogenic sarcoma. The most prevalent site was the femur, and pathologic fracture with focal osteolysis was present in 50% of patients at the initial appearance of the tumor. Healing at the fracture site was demonstrated in one patient. Another patient died of uncontrollable hemorrhage. A case of malignant lymphoma in Paget disease is recorded.

CONCLUSIONS: Surgery or biopsy should be preceded by preoperative scintigraphic bone blood flow evaluation and, if necessary, administration of a preoperative course of mithramycin and selective embolization to minimize bleeding. The prognosis of malignant transformation in Paget disease is poor, although one patient with malignant lymphoma survived after aggressive treatment. Early biopsy and aggressive treatment should not be delayed.