A Presacral Solitary Fibrous Tumor with Extramedullary Hematopoiesis: Radiologic and Pathologic Findings
An asymptomatic 40-year-old woman was referred to our Hospital to investigate a pelvic mass detected by a gynecological ultrasonography in a private diagnostic center. She suffered from epilepsy well controlled with carbamazepine. Routine blood chemistry revealed a sideropenic anemia (RBC 3.60×1012/L; Hb 9.7µg/dL; MCV 73.9 fL; HCT 26.6%; MCH 26.9 pg; MCHC 35.1 g/dL; plasma-iron concentration 40 µg/dL; plasma-transferrin concentration 179 mg/dL), decrease of blood levels of sodium (129 mmol/L) and chlorine (90 mmol/L). Urinalysis was normal. Serum level of CA 15-3 was slightly elevated (43 U/mL; upper normal limit 32 U/mL); serum CA 125, CEA, Alpha-FP and CA 19-9 were within normal limits.\nComputed tomography (CT) detected a presacral well demarcated lobulated mass, measuring 12.5×9×10 cm; the lesion was homogenously hypoattenuating relative to muscles on non-contrast enhanced scans and inhomogeneously hyperattenuating on contrastenhanced scans; neither intratumoral fat nor calcium deposits were evident (). The mass displaced the rectum on the right side, the vagina and the uterus anteriorly, without evidence of local spread or erosion of the sacrum and the coccyx ().\nThe patient was then investigated with a 3T magnetic resonance imaging (MRI). The mass was homogenously isointense to the muscles on T1-weighted MRI (). On T2-weighted MRI the mass was well demarcated by a hypointense capsule and heterogeneous but hyperintense on T2-wheighted fat saturation images (); diffusion weighted images demonstrated a water diffusion restriction (). The mass strongly enhanced after intravenous gadolinium contrast medium administration; small non-enhanced foci and hypertrophic vessels were also appreciable ().\nNo nuclear medicine investigation was performed.\nThe patient was then operated on and rapidly recovered after surgery. She was free from local recurrence and metastases on the basis of a MRI and an whole body CT one year after the operation.\nGrossly the tumor was well circumscribed, firm, homogeneous and brownish in color, measuring 10 cm in diameter on cut surface.\nMicroscopically it was a mesenchymal neoplasm characterized by ovoid or spindle cells with focal nuclear pleomorphism and by a prominent branching, hemangiopericytomalike vascular pattern (). There was no evidence of necrosis and the mitotic activity was low (1 mitosis/10 HPF).\nThe immunohistochemical examination showed staining for CD34, bcl2 and vimentin, and negativity for desmin, smooth muscle actins, various cytokeratins, S100 protein, Synaptophysin and Chromogranins.\nIn addition the presence of sparse multinucleated cells prompted the search for extramedullary hematopoiesis, which was confirmed by specific immunostainings for megakaryocytes (CD61), precursors of granulocytes (myeloperoxydase) and of red blood cells (CD71) ().