A Case of Solitary Fibrous Tumor of the Retroperitoneum, Metastatic to the Lung and the Parotid Gland After an 11-year Disease-free Interval

Abstract

Background. Solitary fibrous tumor is a rare mesenchymal neoplasm. We report a rare case of multiple metastases 11 years after resection of the initial tumor. Case. A 75-year-old woman was admitted to our hospital with swelling of the right parotid gland. Computed tomographic scanning revealed a tumor, 20 mm in diameter, in the right parotid gland. In spite of negative aspiration cytology, the tumor had enlarged in the previous year and was resected. Simultaneously, radiographic examination of the chest revealed three pulmonary nodules. Under the suspicion of metastatic tumor, we resected all of these tumors. These tumors showed hypercellularity of spindle cells with markedly atypical nuclei, immunoreactive with CD34 and bcl-2. Histopathologically, a diagnosis of solitary fibrous tumor was made. These tumors showed the same histological features as the tumors resected from the retroperitoneal space 11 years previously. Conclusion. From the histopathologic features and the clinical course, we concluded that the solitary fibrous tumor in the retroperitoneal space had metastasized to the lung and parotid gland. Long-term follow-up is recommended for solitary fibrous tumors, because of its potential malignancy.