Soft Tissue Pseudosarcomas.

Soft tissue pathology is one of the most challenging areas of diagnostic pathology, not only because of the morphologic diversity of such lesions, but also because of their rarity and pathologists' subsequent lack of exposure to these tumors. Many lesions mimic malignant mesenchymal neoplasms, collectively referred to as "pseudosarcomas." The list of proliferations that can simulate a sarcoma is extensive and heterogeneous. This review addresses malignant, nonmesenchymal neoplasms; mesenchymal neoplasms that histologically mimic sarcomas but are benign; and benign reactive soft tissue lesions that are neither neoplastic nor malignant, but have worrisome clinical and/or morphologic features.