Calcifying fibrous pseudotumor of the pleura.

Calcifying fibrous pseudotumor is an uncommon benign lesion that has unique histologic features. We report a case of calcifying fibrous pseudotumor of the pleura occurring in a 31-year-old woman. A computed tomographic scan revealed a pleural mass in the right anterior costophrenic angle. The excised mass was well circumscribed, nonencapsulated, solid, and firm. The tumor showed dense hyalinized collagenous tissue interspersed with spindle cells, psammomatous calcifications, and a predominantly lymphoplasmocytic infiltrate. Most spindle cells were diffusely positive for vimentin, focally positive for CD34, and negative for desmins, smooth muscle actin, S-100 protein, and anaplastic lymphoma kinase-1.