Spindle Cell Lipoma
Differential Diagnosis
- Pleomorphic lipoma
- Mature fat with admixed other components
- Predominantly spindled
- Predominantly myxoid
Spindle Cell Lipoma vs. Pleomorphic Lipoma
- We consider these to be part of a spectrum
- Mixtures are common
- If atypical cells are present, location becomes definitional
- Restricted to posterior neck, upper back, shoulders
Spindle Cell Lipoma |
Angiolipoma |
Predominantly back of neck, upper back, shoulders |
Very rare on neck, upper back |
Usually solitary |
Frequently multiple |
CD34 positive |
CD34 stains only endothelium and scattered cells |
Prominent spindle cell component |
Prominent vascularity |
No fibrin thrombi |
Frequent fibrin thrombi |
May contain pleomorphic cells (admixed pleomorphic lipoma) |
No pleomorphic cells |
Both contain spindle cell and adipose components and both are CD34 positive in the spindled component
Spindle Cell Lipoma |
Fibrolipoma |
Predominantly back of neck, upper back, shoulders |
Various locations |
Prominent spindle cell component |
Lacks prominent spindle cells |
CD34 positive |
CD34 negative |
Ropy bundles of collagen |
Lacks ropy collagen |
Spindle Cell Lipoma |
Fibrolipomatous Hamartoma of Nerve |
Predominantly back of neck, upper back, shoulders |
Usually involves median nerve |
Does not involve nerves |
Infiltrates and surrounds large nerve |
Usually age 40-70 |
Presents under age 30 |
No neural symptoms |
Neural symptoms |
Spindle Cell Lipoma |
Myolipoma |
Restricted to back of neck, upper back, shoulders |
Predominantly pelvic |
Scant cytoplasm |
Tapered cytoplasm in spindle cells |
Ropey collagen frequent |
No ropey collagen |
CD34 positive |
CD34 negative |
Actin negative |
Actin positive |
Spindle Cell Lipoma |
Atypical Spindle Cell Lipomatous Tumor |
Restricted to back of neck, upper back, shoulders |
Various locations |
Bland spindle cells |
Mild to moderate atypia of spindle cells |
Ropy collagen bundles |
No ropy collagen |
Circumscribed |
May be infiltrative |
Uniformly strong CD34 |
CD34 only 5% reactive |
Rb loss in all cases |
Rb normally expresed in 40$ |
MDM2 and CDK4 negative to weak focal in 5% (FISH negative)
Spindle Cell Lipoma |
Schwannoma or Neurofibroma |
S100 negative except for mature fat |
S100 positive |
Uniformly strong CD34 |
CD34 only scattered small spindle cells |
Spindle Cell Lipoma |
Solitary Fibrous Tumor |
Fat is integral part of lesion |
Fat only at infiltrative border |
May contain pleomorphic cells if admixed with pleomorphic lipoma |
No large pleomorphic cells |
Ropey collagen bundles |
Finely dispersed collagen |
Lacks staghorn vessels |
Frequent staghorn vessels |
Myxoid Liposarcoma |
Spindle Cell Lipoma with Myxoid Stroma |
Infrequent prominent spindle cell component |
Prominent spindle cell component |
Prominent "chicken wire" vascular pattern |
Lacks "chicken wire" vascular pattern |
No dense collagen bundles |
Dense collagen bundles |
Very rare in subcutis or dermis |
Usually in subcutis or dermis |
CD34 negative or scattered small cells |
CD34 widely positive |
t(12;16) or t(12;22) |
Frequent abnormalities of chromosomes 13 or 16 |
Myxolipoma |
Spindle Cell Lipoma with Myxoid Stroma |
Lacks prominent spindle cell component |
Prominent spindle cell component |
May have prominent vascularity |
Vascularity rarely prominent |
No dense collagen bundles |
Dense ropy collagen bundles |
Location variable |
Largely restricted to back, shoulders, posterior neck |
Spindle Cell Lipoma, Myxoid Predominant |
Superficial Angiomyxoma |
Usually has areas of typical spindle cell lipoma |
Lacks areas of typical spindle cell lipoma |
Parallel arrays of spindle cells in areas |
Randomly arranged cells |
Ropey collagen bundles |
Lacks ropey collagen |
Lacks neutrophils or entrapped adnexae |
Frequent neutrophils and entrapped adnexae |