Myxoid Neoplasms

Myxoid tumors of soft tissue constitute a heterogeneous group of neoplasms characterized by the presence of a myxoid stromal matrix, which appears on H&E as an amorphous material and may be confused with edema. Superficial myxoid lesions in general are benign and deep ones are malignant. Grossly, they have a variable gelatinous quality and overlapping histologic features that may present diagnostic difficulties for pathologists. Most are sporadic neoplasms, with only a small percentage arising in patients with hereditary disorders. Discussed are key features of classic myxoid lesions, histologic features, characteristic clinical presentations, immunohistochemical patterns, cytogenetic analysis, and differential diagnosis.