Section 2 Atypia

Definition: this refers to the extent to which tumor cells different from their origin normal cells.

obviously: poor differentiation, malignant

slightly: well differentiation, benign

1. Atypia of tumor tissue structure

benign tumor: slightly change in pattern, including structure

malignant tumor: obviously, disorder arrangement, direction, cell layers,

and cell rank order.

2. Atypia of tumor cells

Benign tumor: slightly Malignant tumor: obviously(1) Pleomorphism: of tumor cellsVariation in size and shape Some extremely small and primitive

appearingSome many times larger than their

neighbors, even tumor giant cells

(2) Pleomorphism of nuclei

① Large nuclear the nuclear to cytoplasmic ratio may approach 1:1 (the normal 1:4~6)

② Hyperchromatic dark staining (containing abundance of DNA)

③ Sometimes have two nuclei, even multi nuclei giant cell.

④ The nuclear shape is usually variable.

⑤ Numerous mitoses the most important is appear atypical,

bizarre mitotic figures as non- symmetry, tripolar, quadripolar, multipolar spindles and abortion types pathologic mitoses.

⑥ Nuclear membrane became thick the chromatin is often coarsely clumped

⑦ Large nucleoli

(3) Changes in cytoplasm

Basophilic

Atypia (Quoted from Rubbin’s 《 Basic Pathology 》 )

non- symmetry, tripolar, quadripolar, multipolar spindles and abortion types pathologic mitoses.

non- symmetry(left), tripolar(middle), and abortion types(right) of pathologic mitoses.

3. Atypia of tumor ultrastructure The difference mainly in quantity

compared with normal cells

(1) Large nuclei and nucleoli, irregular shape, and multiply.

(2) Heterochromatin increase, coarsely clumped and distributed along the nuclear membrane.

(3) Mitochondrion, endoplasmic reticulum, and

Golgi complex hypogenesis, abnormal shape and decreased number.

(4) More dissociative nuclein

(5) More lysosomes

(6) The cellular junction decrease

(7) Microvillus: variation in shape, number, and arrange mount