Pathology: desmoid fibromatosis

Desmoid fibromatosis

  • Lobulated; spindle-stellate cells with vague fascicular pattern

  • Eosinophilic cytoplasm with long bipolar processes

  • Ovoid and elongated wavy nuclei with pinpoint nucleoli; occasional mitotic activity

  • Abundant collagenous matrix, including "keloid-like" collagen

  • Delicate thin-walled vasculature


Desmoid fibromatosis

  • Infiltrative; spindle-stellate cells with vague fascicular pattern

  • Eosinophilic cytoplasm with long tapering processes

  • Ovoid and wavy nuclei with pinpoint nucleoli; occasional mitotic activity

  • Abundant collagenous matrix with prominent small vessels

Desmoid fibromatosis

  • Spindle-stellate cells with vague fascicular pattern

  • Eosinophilic cytoplasm with long tapering processes

  • Ovoid and buckled nuclei with pinpoint nucleoli; inconspicuous mitotic activity

  • Abundant collagenous matrix with prominent small vessels

  • IHC: beta-catenin

Desmoid fibromatosis

  • Spindle-stellate cells with vague fascicular pattern

  • Eosinophilic cytoplasm with long tapering processes

  • Ovoid nuclei with pinpoint nucleoli; inconspicuous mitotic activity

  • Abundant "keloid-like' collagenous matrix with prominent small vessels

  • IHC: beta-catenin

  • DNA-seq: CTNNB1 exon 3 mutation; c.121A>G (p.T41A)

Desmoid fibromatosis

  • Spindle-stellate cells with vague fascicular pattern

  • Eosinophilic cytoplasm with long tapering processes

  • Ovoid and wavy nuclei with pinpoint nucleoli; inconspicuous mitotic activity

  • Abundant collagenous matrix with prominent small vessels

  • IHC: beta-catenin

Desmoid fibromatosis

  • Infiltrative; spindle-stellate cells with vague fascicular pattern

  • Eosinophilic cytoplasm with long tapering processes

  • Ovoid and wavy nuclei with pinpoint nucleoli; occasional mitotic activity

  • Abundant collagenous matrix with prominent small vessels; entrapment of glandular epithelium