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
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
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
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
Spindle-stellate-epithelioid cells in vague fascicules and clusters
Pale amphophilic cytoplasm
Ovoid-round nuclei with prominent nucleoli and mild pleomorphism; mitotic activity
Collagenous-myxoid stroma
Mixed inflammatory infiltrate, including lymphocytes, plasma cells, eosinophils and histiocytes
IHC: ALK1
RNA-seq: EML4::ALK gene fusion
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