Pathology: epithelioid haemangioendothelioma

Epithelioid haemangioendothelioma, conventional

• Sheets and cords of epithelioid cells

• Pale eosinophilic cytoplasm with occasional vacuoles

• Ovoid nuclei with small nucleoli and mild pleomorphism; inconspicuous mitotic activity

• Myxohyaline stroma 

• IHC: ERG

• RNA-seq: WWTR1::CAMTA1 gene fusion

Epithelioid haemangioendothelioma, conventional

• Sheets and cords of epithelioid cells

• Pale eosinophilic cytoplasm with occasional vacuoles

• Ovoid nuclei with small nucleoli and mild pleomorphism; inconspicuous mitotic activity

• Myxohyaline stroma 

• IHC: ERG

• RNA-seq: WWTR1::CAMTA1 gene fusion

Epithelioid haemangioendothelioma, conventional

• Nests-cords of epithelioid cells

• Pale eosinophilic cytoplasm with occasional vacuoles

• Ovoid nuclei with small nucleoli and mild pleomorphism; inconspicuous mitotic activity

• Occasional myxohyaline stroma; necrosis

• IHC: ERG

• RNA-seq: WWTR1::CAMTA1 gene fusion

Epithelioid haemangioendothelioma, conventional

• Fascicles of epithelioid cells

• Pale eosinophilic cytoplasm with occasional vacuoles containing amorphous debris

• Ovoid nuclei with small nucleoli and mild pleomorphism; inconspicuous mitotic activity

• Occasional myxohyaline stroma; incomplete rim of metaplastic bone* 

• IHC: ERG

• RNA-seq: WWTR1::CAMTA1 gene fusion

* Calcification is a rare event in these tumours

Epithelioid haemangioendothelioma, conventional

• Nests-cords of epithelioid cells

• Pale eosinophilic cytoplasm with rare vacuoles

• Ovoid nuclei with small nucleoli, occasional multinucleation and moderate pleomorphism;* inconspicuous mitotic activity

• Occasional myxohyaline stroma

• IHC: CD34, ERG

• RNA-seq: WWTR1::CAMTA1 gene fusion

* This tumour exhibits an atypical degree of pleomorphism

Epithelioid haemangioendothelioma, conventional

• Spindle-stellate-round cells in nests and cords

• Pale eosinophilic cytoplasm with occasional vacuoles 

• Round-ovoid hyperchromatic nuclei with mild pleomorphism; inconspicuous mitotic activity

• Abundant myxohyaline stroma

• IHC: ERG

• RNA-seq: WWTR1::CAMTA1 gene fusion

Epithelioid haemangioendothelioma, conventional

• Nests-fascicles of epithelioid cells

• Pale eosinophilic cytoplasm with occasional vacuoles containing amorphous debris

• Ovoid nuclei with small nucleoli, occasional pseudonuclear inclusions and mild pleomorphism; inconspicuous mitotic activity

• Occasional myxohyaline stroma; peripheral lymphoid aggregates

• IHC: ERG

• RNA-seq: WWTR1::CAMTA1 gene fusion

• PMID: 33125182

Epithelioid haemangioendothelioma, TFE3-rearranged

• Circumscribed; sheets-nests of epithelioid cells

• Pale eosinophilic cytoplasm,with occasional vacuoles containing amorphous debris

• Ovoid nuclei with small nucleoli and mild pleomorphism; inconspicuous mitotic activity

• Occasional myxohyaline stroma; lipomatous background

• IHC: ERG, TFE3

• RNA-seq: YAP1::TFE3 gene fusion

• PMID: 34381186

Epithelioid haemangioendothelioma, TFE3-rearranged

• Nests of epithelioid-polygonal cells

• Pale amphophilic cytoplasm

• Eccentric ovoid nuclei with vesicular chromatin, small nucleoli and mild pleomorphism; inconspicuous mitotic activity

• Intervening fibrous stroma

• IHC: TFE3

• FISH: YAP1::TFE3 gene fusion

• PMID: 23737213