Pathology: myolipoma of soft tissue

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