Here are three abnormal mitoses. Mitoses by themselves are not indicators of malignancy. However, abnormal mitoses are highly indicative of malignancy. The marked pleomorphism and hyperchromatism of surrounding cells also favors malignancy.

图示：病理性核分裂

核分裂的出现不能说明恶性肿瘤的存在。然而病理性核分裂高度提示恶性肿瘤。周围的多形性细胞及染色过深的细胞均提示恶性肿瘤。

This large fleshy mass arose in the retroperitoneum and is an example of a sarcoma. Sarcomas arise from mesenchymal tissues. This one happened to be a "malignant fibrous histiocytoma" which is a wastebasket term for sarcomas that do not resemble mesenchymal cells such as striated muscle (rhabdomyosarcoma), smooth muscle (leiomyosarcoma), fat (liposarcoma), blood vessels (angiosarcoma), bone (osteosarcoma), or cartilage (chondrosarcoma). Sarcomas are big and bad.

这个大的肉质样肿块发生于腹膜后，属于肉瘤，来源于间叶组织。图为：恶性纤维组织细胞瘤。

Sarcomas tend to have a spindle cell pattern. Note that some of the cells are much larger and very pleomorphic.

肉瘤细胞多呈梭形。图示：有些细胞非常大而且形态多样。

This sarcoma is composed of very pleomorphic cells.

图示：肉瘤由异型性很大的细胞组成。

This sarcoma has many mitoses. A very large abnormal mitotic figure is seen at the right.

图示：肉瘤肿瘤细胞核分裂

图右侧可见一明显的病理性核分裂细胞。

This sarcoma is stained for vimentin by immunoperoxidase. The positive neoplastic cells are invading into normal muscle fibers (which are not staining for vimentin) at the left. This is a typical staining reaction for sarcomas.

免疫过氧化物酶染色示：vimentin(波形蛋白阳性)。此种肿瘤细胞正向左侧的正常肌纤维(没有被染上相应颜色)浸润。这是一种典型的肉瘤染色反应。

Here is an osteosarcoma of bone. The large, bulky mass arises in the cortex of the bone and extends outward.

图示：骨肉瘤。大肿块发生于骨皮质向外部生长。

The osteosarcoma is composed of spindle cells. The pink osteoid formation seen here is consistent with differentiation that suggests osteosarcoma.

骨肉瘤由梭形细胞组成。粉红色的类骨质显示一定的分化程度，提示骨肉瘤。

This large mass lesion is a liposarcoma. Common sites are the retroperitoneum and thigh, and they occur in middle aged to older adults. This one is yellowish, like adipose tissue, and is well-differentiated. Though indolent, it continues growing to reach a large size, and following excision, it has a tendency to recur.

图示：脂肪肉瘤。多发生于腹膜后和股部，好发于中老年人。

呈淡黄*色、分化相对较成熟，虽然没有疼痛，但切除后往往容易复发。

This liposarcoma has enough differentiation to determine the cell of origin, but there is still significant pleomorphism of the neoplastic cells.

脂肪肉瘤分化较好，能够很好判断组织来源，但是肿瘤细胞的异型性仍然很大。