Pathology: inflammatory myofibroblastic tumour

Inflammatory myofibroblastic tumour

  • Circumscribed; cellular; fascicles of spindle-epithelioid cells

  • Pale amphophilic cytoplasm

  • Monomorphic ovoid nuclei with prominent nucleoli; occasional mitotic activity

  • Mild chronic inflammatory infiltrate

  • IHC: ALK1

  • RNA-seq: EML4::ALK gene fusion

Inflammatory myofibroblastic tumour

  • Circumscribed; cellular; fascicles of spindle-epithelioid cells

  • Pale amphophilic cytoplasm

  • Monomorphic ovoid nuclei with prominent nucleoli; occasional mitotic activity

  • Mild chronic inflammatory infiltrate

  • IHC: ALK1

  • RNA-seq: IGFBP5::ALK gene fusion

Inflammatory myofibroblastic tumour

  • Circumscribed; cellular; spindle cell fascicles

  • Eosinophilic cytoplasm

  • Monomorphic ovoid nuclei with prominent nucleoli; occasional mitotic activity

  • Mild chronic inflammatory infiltrate

  • RNA-seq: TNS1::ALK gene fusion

Inflammatory myofibroblastic tumour

  • Cellular; spindle cell fascicles

  • Abundant pale amphophilic cytoplasm

  • Round-ovoid nuclei with prominent nucleoli and mild pleomorphism; occasional mitotic activity

  • Chronic inflammatory infiltrate

  • IHC: ALK1

  • RNA-seq: FN1::ALK gene fusion

Epithelioid inflammatory myofibroblastic sarcoma

  • Variable cellularity; spindle-stellate-epithelioid cells in vague fascicules and clusters

  • Pale amphophilic cytoplasm

  • Ovoid-round nuclei with prominent nucleoli and mild pleomorphism; conspicuous mitotic activity

  • Collagenous-myxoid stroma

  • Mixed inflammatory infiltrate, including lymphocytes, plasma cells, neutrophils, eosinophils and histiocytes

  • IHC: ALK1

  • RNA-seq: RRBP1::ALK gene fusion

  • PMID: 21164297