Updates in spindle cell/pleomorphic lipomas

Exceptionally large, atypically located spindle cell lipoma

“…SCLs are a rare subtype of benign lipomatous tumours often considered to be on a histological spectrum with pleomorphic lipoma, another rare subtype of lipoma with similar cytogenetic abnormalities. The two subtypes share a known genetic chromosomal abnormality, specifically losses at 16q and 13q chromosomes 2 3 9. A recent series examining 18 SCLs and histologically similar tumours demonstrated that all SCLs lacked Rb-1 expression, which is located on chromosome 13q 10.…”

“…A recent series examining 18 SCLs and histologically similar tumours demonstrated that all SCLs lacked Rb-1 expression, which is located on chromosome 13q 10. Pleomorphic liposarcoma can be differentiated from SCL based on the presence of unique giant cells with overlapping, marginally placed nuclei—referred to as ‘floret giant cells’ 2…”

“…The classic histological appearance of SCLs contains a triad of mature adipocytes, ropey collagen and bland spindle cells—occasionally within a myxoid stroma. Lipoblasts may be present but are very rare, and there are no mitoses with minimal, if any, nuclear atypia compared with liposarcoma or pleomorphic lipoma 2 7 9…”

“…SCLs demonstrate strong, diffuse CD34 expression and vimentin-positive staining within the spindle cell cytoplasm. The absence of lipoblasts and lack of significant nuclear atypia are key to ruling out liposarcoma, and other similar cytological pathologies, such as pleomorphic lipoma 2. The absence of MDM2 amplification or CDK4 assists in differentiating SCL from ALT (previously well-differentiated liposarcoma) 7–9.…”

“…Spindle cell lipomas (SCLs) are a rare subtype of lipoma. They classically appear as a subcutaneous, slow-growing and painless mass in the shawl region (shoulders, posterior neck and upper back) of men 50–70 years old at an average size of 4–5 cm 1 2. In individual cases, SCLs have been reported in atypical locations including the face, thigh, upper arm, forearm, wrist, thumb and very rarely the hand 3–7.…”