Histology of gastrointestinal stromal tumor (GIST) with spindle cell and epithelioid morphology

Spindle cell and epithelioid histologic patters of GIST.
(A) Biopsy specimen (20x) of a spindle cell GIST stained with hematoxylin and eosin (H&E). Histologically, the tumor is composed of fairly uniform spindle cells with elongated nuclei and eosinophilic cytoplasm, growing in fascicles.
(B) Biopsy specimen (20x) of an H&E-stained section of an epithelioid GIST with rounded cells, round central nuclei, and eosinophilic or clear cytoplasm. Note the nested morphology.