Bloom–Richardson grading system

Bloom–Richardson grading system (also known as the Nottingham grading system) is a histopathological grading system used to determine the aggressiveness of breast cancer. It was developed by pathologists F. W. Bloom and D. W. Richardson in the mid-20th century. The system is based on the assessment of three morphological features: tubule formation, nuclear pleomorphism, and mitotic count. Each feature is scored from 1 to 3, and the scores are then added together to give a final grade between 3 and 9.

History

The Bloom–Richardson grading system was first proposed in 1957 by F. W. Bloom and D. W. Richardson. It was later modified by Elston and Ellis in 1991, and is now often referred to as the Nottingham grading system.

Grading Criteria

The Bloom–Richardson grading system evaluates three morphological features of the tumor:

1. Tubule Formation: This refers to the percentage of the tumor that forms tubular structures. A score of 1 indicates that more than 75% of the tumor forms tubules, a score of 2 indicates that between 10% and 75% forms tubules, and a score of 3 indicates that less than 10% forms tubules.
2. Nuclear Pleomorphism: This refers to the variation in size and shape of the tumor cell nuclei. A score of 1 indicates small, regular nuclei, a score of 2 indicates moderate variation, and a score of 3 indicates marked variation.
3. Mitotic Count: This refers to the number of cells undergoing mitosis per high power field. A score of 1 indicates less than 10 mitoses, a score of 2 indicates 10 to 20 mitoses, and a score of 3 indicates more than 20 mitoses.

The scores for each feature are added together to give a final grade between 3 and 9. A total score of 3 to 5 is considered grade 1 (well differentiated), 6 to 7 is considered grade 2 (moderately differentiated), and 8 to 9 is considered grade 3 (poorly differentiated).

Clinical Significance

The Bloom–Richardson grading system is widely used in clinical practice to predict the prognosis of breast cancer. Higher grades are associated with a worse prognosis and a higher risk of metastasis. The grade can also guide treatment decisions, as higher-grade tumors may require more aggressive treatment.

See Also

• Breast cancer
• Histopathology
• Mitosis
• Nuclear pleomorphism
• Tubule formation