Fig. 1

Micrographs of cutaneous mass in postoperative histological examination. a A solitary well-circumscribed mass was found in the deep dermis without epidermal connection. The tumor cells formed nodule or solid nests separated by densely fibroblastic stroma. b Higher magnification showed the two types of tumor cell mixed in the solid nest. c Under the high power field, one type of tumor cell was round to polygonal cells, which had eosinophilic, relatively narrow cytoplasm. The other had abundant pale or foamy cytoplasm. Both two types of tumor cell had enlarged nuclei with distinct nucleoli. d The tumor cells showed mild to moderate atypia with scattered mitotic figures (black arrow). e There were scattered glandular or rosette-like structures identified within the tumor nodules (black arrow). f The tumor cells were observed to spread into the subcutaneous fatty tissue with neural invasion. a, H&E staining with original magnification × 100; b-f, H&E staining with original magnification × 400)