Table 4.

Differential diagnoses of MLS.

Diagnosis	Morphology	IHC	Common Genetic Alterations
Lipoblastoma	Lobulated architecture with fibrous septa with often prominent vasculature; possibly myxoid stroma with possibly plexiform vasculature; resembling fetal fat with prelipoblasts, lipoblasts, and mature fat in variable portions	Not specific	PLAG1 rearrangements (various fusion partners)
Myxoid pleomorphic liposarcoma	Progressive transition between areas resembling myxoid liposarcoma and pleomorphic liposarcoma; pleomorphic cells; and myxoid matrix	Not specific	RB1 deletion, TP53 mutations
Chondroid lipoma	Myxohyaline chondroid matrix; lipoblasts intermingled with mature adipocytes and chondroid cells; and vascularized septa	S100 (mature adipocytes and lipoblasts); keratins (rare)	C110r95-MRTFB
Soft tissue angiofibroma	Myxoid-collagenous stroma; prominent, branching vasculature; and bland spindle cells, possibly adipocytes	CD34, EMA, desmine (dendritic cells)	NCOA2 rearrangements (various fusion partners)
Small, blue round-cell tumors (when round-cell liposarcoma)	Cells with small round-oval-spindle cells with little cytoplasm	See Table Ewing and Ewing-like sarcomas	See Table Ewing and Ewing-like sarcomas