Surgical Pathology Criteria

Atypical Spindle Cell Lipomatous Tumor


Alternate / Historical Names

Diagnostic Criteria

Supplemental Studies


Differential Diagnosis

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)

Neurofibroma with Fat Component Atypical Spindle Cell Lipomatous Tumor
Hypocellular Moderate cellularity
Wavy nuclei Spindled, nonwavy nuclei
No nuclear pleomorphism Mild to moderate atypia
May be seen in children Rare under 30
Poorly circumscribed May be circumscribed

Dermatofibrosarcoma Protuberans Atypical Spindle Cell Lipomatous Tumor
No cytologic atypia Mild to moderate atypia
Entrapped fat at periphery Fat integral to lesion
No lipoblasts Lipoblasts frequently present

Spindle Cell Atypical Lipomatous Tumor Low Grade Fibromyxoid Sarcoma
Adult fat integral to lesion No fat component
Lipoblasts may be present No lipoblasts
Abnormal mitotic fibures may be present No abnormal mitotic figures
Areas may be histologically identical


Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting : July 29, 2007
Last update: 3/14/16

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