Pathology: myofibroblastoma

Myofibroblastoma, mammary-type

  • Circumscribed and unencapsulated; short spindle cell fascicles

  • Eosinophilic cytoplasm

  • Monomorphic ovoid nucleoli with small nucleoli; inconspicuous mitotic activity

  • Intervening stroma is collagenous

  • IHC: CD34

Myofibroblastoma, mammary-type

  • Circumscribed; short spindle cell fascicles

  • Eosinophilic cytoplasm

  • Monomorphic ovoid nucleoli with small nucleoli; inconspicuous mitotic activity

  • Intervening stroma is myxoid with collagen bands; prominent adipocytic component

  • IHC: CD34, desmin, RB1

Myofibroblastoma, mammary-type

  • Short spindle cell fascicles

  • Eosinophilic cytoplasm

  • Monomorphic ovoid nucleoli with small nucleoli; inconspicuous mitotic activity

  • Intervening stroma is myxoid with broad collagen bands; interspersed adipocytes

  • IHC: CD34, desmin

Myofibroblastoma, intranodal palisaded (intranodal haemorrhagic spindle cell tumour with amianthoid fibres)

  • Circumscribed; spindle cells in short fascicles

  • Fibrillary eosinophilic cytoplasm

  • Monomorphic ovoid-elongated nuclei with areas of palisading; inconspicuous mitotic activity

  • Prominent interstitial haemorrhage and haemosiderin deposition; so-called "amianthoid" fibres (hyalinized collagenous bodies) with focal calcium deposition; lymphocytic cuff

  • IHC: smooth muscle actin

  • PMID: 25025452

Myofibroblastoma, intranodal palisaded (intranodal haemorrhagic spindle cell tumour with amianthoid fibres)

  • Spindle cells in short fascicles

  • Fibrillary eosinophilic cytoplasm

  • Monomorphic ovoid-elongated nuclei with areas of palisading; inconspicuous mitotic activity

  • So-called "amianthoid" fibres (hyalinized collagenous bodies); lymphocytic cuff at end of core

  • IHC: smooth muscle actin

  • PMID: 25025452