Image Description
Microscopic Features: The main finding is multinucleated giant cells with deeply eosinophilic cytoplasm and hyperchromatic nuclei in a wreath-like arrangement (floret giant cells). Other histologic features are similar to those seen in spindle cell lipomas, including bland spindle cells arranged in fascicles, collagen bundles, numerous mast cells, and fibromyxoid stroma. Scattered lipoblasts may be seen and should not be used as a basis for the diagnosis of liposarcoma in the absence of other features.
About the Disease
Spindle cell and pleomorphic lipomas are uncommon benign lipomatous tumors with overlapping clinical, morphologic, and cytogenetic features. They represent morphologic continuum of the same entity. They occur in 45-60 yr. age group with a strong male predilection. Majority (80%) arise in the posterior neck, shoulder, or upper back as slow-growing, solitary, well-circumscribed, firm, painless subcutaneous nodules, usually < 5 cm in size.The morphology depends upon the relative proportion of mature adipose tissue, spindle cells, and fibromyxoid stroma. Some tumors are lipoma-like with abundant fat and only scattered foci of spindle cells. Others are grey-white firm tumors composed of spindle/pleomorphic cells with only rare foci of adipose tissue. The background stroma is fibromyxoid or collagenous with abundant mast cells and thick ropy collagen bundles. Pleomorphic lipomas resemble spindle cell lipomas but also contain floret giant cells with hyperchromatic nuclei in a wreath-like arrangement.Deletions of 13q14 (or entire chromosome 13) with loss of tumor suppressor gene RB1 are found in the majority of cases. The same deletion is also found in cellular angiofibroma and mammary and soft tissue myofibroblastomas.