CLINICAL NOTES: R lung mass 150 x 110 x 80 mm. The piece is roughly pyramidal in shape with multiple staple lines, 10-85mm. On one side is a thick pale glassy plaque over the surface 170 x 60 mm. The remainder of the tissue has a white/pale/deep red, partially smooth and vaguely nodular surface. A few dilated vessels are seen, that have smooth pale walls <1mm thick. There is a relative well circumscribed area that is firm lobular and with a whorled appearance, 40 mm in greatest dimension.
MICROSCOPIC DESCRIPTION: The sections show a tumour, surrounded by a small amount of lung tissue. The tumour shows mild to moderate increase in cellularity, forming short fascicles. There are intermixed areas of fibrosis in the background. The tumour cells have elongated nuclei with no nuclear pleomorphism, inconspicuous nucleoli and ill-defined cytoplasm. There are scattered staghorn type blood vessels in the stroma. Sparse mitoses are noted, less than 4 per 10 high power fields. No necrosis is present. There is no evidence of lymphovascular invasion. The tumour cells are CD34, CD99 and bcl-2 positive. The Ki-67 index is about 2%. They are EMA, CAM5.2 and TTF-1 negative. The features are those of solitary fibrous tumour. It appears completely excised. Its behaviour cannot be predicted on histology alone.
DIAGNOSIS: Right lung mass: Solitary fibrous tumour.