Atypical Spindle Cell and Pleomorphic Lipomatous Tumor of the Ocular Adnexa: Two Cases of a Rare Entity.

Atypical spindle cell and pleomorphic lipomatous tumor (ASCPLT) is a rare lipomatous neoplasm that was recently introduced into the World Health Organization Classification of Soft Tissue and Bone tumors as a distinct entity. ASCPLT has potential for local recurrence but does not metastasize. This biologic behavior separates ASCPLT from its morphologic mimics. Ocular adnexal ASCPLT has not been previously reported. Described herein are two patients with ASCPLT. The subcutaneous orbital rim lesion featured markedly pleomorphic spindle and multinucleated cells. The eyelid lesion was dominated by atypical spindle cells in a background of mature adipocytes. Both neoplasms demonstrated infiltrative margins, rare mitotic figures, immunoreactivity for CD34 and loss of Rb1, and the absence of MDM2 amplification by fluorescence in situ hybridization. Recognition of ASCPLT in the differential of ocular adnexal neoplasms may lead to a re-evaluation of morphologically similar tumors, which may have varied biologic behavior and warrant a different management approach.