Update on Superficial Lipomatous Tumors, Emerging Entities and Molecular Correlation.

Lipomatous tumors are among the most common mesenchymal neoplasms. They exhibit significant variability in histologic features, anatomic location, and clinical behavior. This review focuses on superficial lipomatous neoplasms. In practice, most of the superficial lipomatous tumors are benign with possible potential for local recurrence; however, atypical and fully malignant lipomatous tumors do occur in superficial locations and may be overlooked as differential diagnosis consideration. In addition to review of histologic features of classic lipomatous tumors such as lipoma, angiolipoma and atypical lipomatous tumor/well-differentiated lipoma/dedifferentiated liposarcoma, this review explores emerging and new entities such as dysplastic lipoma/anisometric cell lipoma, atypical spindle cell and pleomorphic lipomatous tumor/dedifferentiated atypical spindle cell and pleomorphic lipomatous tumor, and expanded morphologic and molecular spectrum of lipoblastoma.