Context Solitary fibrous tumor is an uncommon malignancy of spindle cell origin rarely found in the pancreas. A single description of a patient with malignant pancreatic solitary fibrous tumor has previously been published. Case report We report an incidentally found malignant solitary fibrous tumor in a 39-year-old woman who presented with low rectal cancer. The tumor was discovered on her rectal cancer staging workup, and imaging studies were suggestive of solid pseudopapillary neoplasm or pancreatic neuroendocrine tumor. Two attempts at endoscopic ultrasound with fine needle aspiration were not diagnostic. The patient underwent successful pancreaticoduodenectomy with resection of the mass and a total of 19 lymph nodes and adequate margins. Final pathology revealed malignant solitary fibrous tumor by histologic examination and immunohistochemistry, with up to six mitoses per 10 high-power fields. Conclusion Pancreatic solitary fibrous tumors are themselves extremely rare, with only 15 cases reported in the literature. The majority of tumors are discovered incidentally and are considered benign, but a subset of solitary fibrous tumors carry a malignant phenotype. Data on the appropriate management and treatment for malignant solitary fibrous tumor is scarce. However, given their potential for recurrence, lifelong surveillance is recommended.
Clare French, Russell Dorer, Flavio G Rocha