Fig. 1

The pathology and immunohistochemistry of patient A. Hematoxylin and eosin (HE) staining shows the infiltrative growth of tumor cells in the form of thin beams and nested clusters involving the mucosa and submucosa of the small intestine, with obvious tumor cell heterogeneity, pleomorphism, vacuolation of some cells, clearly visible nucleoli, and regional lamellar necrotic changes. Immunohistochemistry indicating that the tumor is positive for CK (pan), Ki-67, and β-hCG. The Ki-67 index is about 25% ± 5%. A HE staining, 20× magnification. B Immunostaining for CK (pan), 20× magnification. C Immunostaining for Ki-67, 20× magnification. D Immunostaining for β-hCG, 20× magnification