Pathology: spindle cell / pleomorphic lipoma

Spindle cell lipoma

  • Sheets of adipocytes with admixed spindle cell fascicles

  • Adipocytes have abundant clear cytoplasm; peripherally located small monomorphic nuclei

  • Spindle cells have eosinophilic cytoplasm; ovoid monomorphic nuclei

  • Prominent bundles of "ropy" collagen

  • IHC: CD34, androgen receptor

Spindle cell lipoma

  • Adipocytes with admixed spindle cell fascicles

  • Adipocytes have abundant clear cytoplasm; peripherally located small monomorphic nuclei

  • Spindle cells have eosinophilic cytoplasm; ovoid monomorphic nuclei

  • Prominent bundles of "ropy" collagen

  • IHC: CD34

Spindle cell lipoma

  • Spindle-stellate cells in loose fascicles

  • Eosinophilic cytoplasm with delicate processes; ovoid monomorphic nuclei

  • Myxoid stroma with bundles of "ropy" collagen; occasional interspersed bland adipocytes

  • IHC: CD34

Spindle cell lipoma, pseudoangiomatous subtype

  • Spindle cell fascicles

  • Eosinophilic cytoplasm; ovoid monomorphic nuclei

  • Myxoid stroma; prominent bundles of "ropy" collagen; rare adipocytes

  • IHC: CD34

Spindle cell lipoma, fat-poor subtype

  • Spindle cell fascicles

  • Eosinophilic cytoplasm; ovoid monomorphic nuclei with hint of palisading

  • Myxoid stroma with prominent thick-walled vasculature

  • IHC: CD34

Spindle cell lipoma, myxoid subtype

  • Spindle-stellate cells in loose fascicles

  • Eosinophilic cytoplasm with delicate processes; ovoid monomorphic nuclei

  • Myxoid stroma with bundles of "ropy" collagen; interspersed bland adipocytes

  • IHC: CD34, androgen receptor

Spindle cell / Pleomorphic lipoma

  • Sheets of adipocytes admixed with spindle cell fascicles

  • Adipocytes have abundant clear cytoplasm with occasional vacuolation; peripherally located small monomorphic nuclei

  • Spindle cells have eosinophilic cytoplasm; ovoid monomorphic nuclei

  • Floret-like multinucleated cells may be interspersed

  • Fibro-myxoid stroma; interspersed bundles of "ropy" collagen

  • IHC: CD34

Pleomorphic lipoma

  • Sheets of adipocytes admixed with spindle-epithelioid cells

  • Adipocytes have abundant clear cytoplasm with occasional vacuolation; peripherally located small monomorphic nuclei

  • Spindle-epithelioid cells have eosinophilic cytoplasm; hyperchromatic round-ovoid nuclei with frequent multinucleation ('Floret-like')

  • Interspersed bundles of "ropy" collagen

Pleomorphic lipoma

  • Sheets of adipocytes admixed with spindle-epithelioid cells

  • Adipocytes have abundant clear cytoplasm with occasional vacuolation; peripherally located small monomorphic nuclei

  • Spindle-epithelioid cells have eosinophilic cytoplasm; hyperchromatic round-ovoid nuclei with frequent multinucleation ('Floret-like')

  • Interspersed bundles of "ropy" collagen; pseudoangiomatous spaces

  • IHC: CD34