Calcifying Fibrous ‘Pseudotumor’

Abstract

Calcifying fibrous pseudotumor (CFP) has been postulated to be a “late” stage of inlammatory myofibroblastic tumor (IMT). We analyzed 15 cases (8 females and 7 males; aged 1 to 65 years). The anatomic distribution was wide, including 3 cases each in neck, mesentery/omentum, and GI tract and 2 cases each in mediastinum and paratesticular sites. Follow-up information was available in 1O patients (range 4 to 228 months). Local recurrence occurred in 3 patients and was repeated in 2. Tuor size ranged from 0.6 to 25 cm. Lesions were well-circumscribed hypocellular spindle cell proliferations with dense stromal collagen, a lymphoplasmacytic infilrate, and stromal calcifications. Features of conventional IMT were not seen. Imunostaining showed CD34 positivity in most cases as well as rare cells positive for smooth muscle actin and desmin, and consistent negativity for ALK-1 and S-100 proein. These findings suggest that CFP is a distinctive benign mesenchymal neoplasm with a low risk for recurrence and, therefore, best labelled as “calcifying fibrous tuor.” There is no convincing evidence to support an association between CFP and IMT.