Admixture of adipocytes and spindle cells arranged in loose fascicles
Adipocytes have abundant clear cytoplasm with minimal variability in size and shape; peripherally located small monomorphic nuclei
Spindle cells have abundant eosinophilic cytoplasm; the nuclei are ovoid, elongated and monomorphic; mitotic activity is inconspicuous
IHC: H-caldesmon; (-) HMB45, Melan-A
FISH: negative for MDM2 amplification
Possibly associated with HMGA2-rearrangement (PMID: 26857357)
Admixture of adipocytes and spindle cells arranged in loose fascicles
Adipocytes have abundant clear cytoplasm with minimal variability in size and shape; peripherally located small monomorphic nuclei
Spindle cells have abundant eosinophilic cytoplasm; the nuclei are ovoid, elongated and monomorphic; mitotic activity is inconspicuous
IHC: H-caldesmon
FISH: negative for MDM2 amplification
Admixture of adipocytes and spindle cells arranged in loose fascicles
Adipocytes have abundant clear cytoplasm with minimal variability in size and shape; peripherally located small monomorphic nuclei
Spindle cells have abundant eosinophilic cytoplasm; the nuclei are ovoid, elongated and monomorphic; mitotic activity is inconspicuous
IHC: H-caldesmon