1. July 2017 Dr Suzannah Yarwood
B3 Breast Core Audit
July 2017
Dr Suzannah Yarwood

2. Reason for audit
Subjective feeling in the breast MDT that an increasing number of percutaneous breast biopsies are being diagnosed as “B3” Change in the pathologists reporting breast cases Preliminary data search suggesting that B3 diagnoses had more than doubled in past year

3. B-Classification
B1 = unsatisfactory / normal tissue only
B2 = benign lesion
B3 = lesion of uncertain malignant potential
B4 = suspicion of malignancy
B5 = malignant B5a = non-invasive B5b = invasive

4. Clinical impact of B3 diagnosis
1. Resource implication for NHS
2. Surgery for patient

5. Method
Data search for all B3 biopsies from 1st April to 31st March in , , , and
Each report verified to check “B3” diagnosis given
Divided results into the following B3 diagnoses: papilloma, complex sclerosing lesion/radial scar, LCIS, phylloides, flat epithelial atypia/ADH or other

6. Results
Number of B3coresTotal 42 50 48 89
Number of cores processed
853
998
991
1004
1101
Percentage of total cores diagnosed B3
4.9
5.00%
4.80% 8%

7. Flat epithelial atypia/ADH category increased by approximately 0
Flat epithelial atypia/ADH category increased by approximately 0.7% of total biopsies compared to previous 4 years

8. Number of biopsies reported as papilloma 10 21 22 14 28
Number of biopsies reported as papilloma 10 21 22 14 28
Number having subsequent excision 6 17 27
Number of these excisions which showed papilloma 4 16
percentage of excised specimens showing papilloma 67
100 94 81
Number of biopsies reported as flat epithelial atypia/ductal atypia/ADH 13 8 6 15 24
Number having subsequent excision 11 7 2 14 20
Number of these excisions which showed flat epithelial atypia/ductal atypia/ADH 5 3
number of excised specimens showing flat epithelial atypia/ductal atypia/ADH or cancer/DCIS 4 9 16
percentage 64 57
100 80

9. Discussion
Our B3 rate for is 8% (NHS BSP median 7%, RCPATH guidelines %)
PPV for FEA/ADH on core biopsy vs FEA/ADH/malignancy on excision= 80%
PPV of FEA/ADH for malignancy = 15% (NHS BSP median 14.6%)
False positive rate for FEA/ADH= 20%

10. RCPATH Suggested thresholds for core biopsy performance
Minimum percentage
Preferred percentage
Current median ( )
B3 rate
4-9% % 7%
Positive predictive value B3
14.6%
* Figures from audit of National Breast Screening Pathology Audit 2015

11. Possible reasons
The B3 figure higher than average due to higher number in flat epithelial/ADH category which is the most subjective of all the categories
Most cases are screening cases, therefore B3 expected to be higher
?Increased sensitivity for B3 lesions
Loss of experienced pathologists recently might lead to more cautious diagnosis for B3
Additional new breast pathologists may affect threshold for B3 diagnosis

12. Recommendation
Retrospective review of all cases diagnosed as atypical ductal hyperplasia/flat epithelial atypia which did not show atypia, dysplasia or malignancy on excision (4 cases out of 20 – 20%)
Continue to double report all cases of flat epithelial atypia/ADH

13. References
El-Sayed M, Rakha E, Reed J, Lee A, Evans A, Ellis I. Predictive value of needle core biopsy diagnoses of lesions of uncertain malignant potential (B3) in abnormalities detected by mammographic screening. Histopathology. 2008; 53(6):650-7 Houssami N, Ciatto S, Bilous M, Vezzosi V, Bianchi S. Borderline breast core needle histology: predictive values for malignancy in lesions of uncertain malignant potential (B3). Br J Cancer 2007;96: 1253–7 Lee A, Denley H, Pinder S, Ellis I, Elston C, Vujovic P, Macmillan R, Evans A. Excision biopsy findings of patients with breast needle core biopsies reported as suspicious of malignancy (B4) or lesion of uncertain malignant potential (B3). Histopathology. 2003; 42 (4): Lieske B, Ravichandran D, Alvi A, Lawrence D, Wright D. Screen-detected breast lesions with an indeterminate (B3) core needle biopsy should be excised. EJSO. 2008; 34(12):