For the time period between January 1996 to December 2005 there are 1183 lesions in our database in which the dominant screen detected abnormality is classified as a category 3B discrete mass.
The number of such cases assessed each year ranged from 61 to 169 lesions per year, with a mean of 118.3 lesions per year. In line with the general expansion of our programme, there has been a steady increase in the number of these lesions assessed over time. In relative terms, they constitute 24.4% of all lesions biopsied. The mean age of the clients was 55.1 years (std 8.8 years, range 40–86 years). Eighty women (6.8%) gave a very strong family history of breast cancer, 1103 women did not (93.2%). In 387 lesions (32.7%) the client had been using hormone replacement therapy (HRT). 794 women had not used HRT (67.1%). This information is unavailable in two cases.
Five hundred and thirty eight lesions (45.5%) were detected in the first round of screening and the remainder in subsequent rounds (rounds 2–12). The lesion was located in the right breast in 48.1% of cases and in the left breast in 51.9%.
In 1001 lesions (84.6% of cases) there was only one lesion. In the remaining 182 lesions (15.4%) a second lesion was also present requiring assessment. By definition, this other lesion was radiologically of grade 3 or higher. The imaging features of a typical discrete mass included in this study are depicted in . This was shown to be a fibroadenoma. The location of the mass was specified in all but five cases. The upper outer quadrant was the most common site (43.5%), followed by the central region (17.5%), upper inner quadrant (15.4%), lower inner quadrant (11.7%), axillary tail (0.8%) and nipple (0.7%). The mean diameter was 13.3
mm (std 8.3
mm, range 2–120
Figure 1 Typical imaging features of a probably benign, circumscribed, discrete mass, graded 3B in our programme. (A) Mammogram, left lateral view, with the arrow pointing to a circumscribed mass. (B) Breast ultrasound of the lesion, showing a circumscribed oblong (more ...) Final outcome
After diagnostic work up, tissue biopsy and long term follow up via two independent means, ninety-eight cases (8.3%) were proven to be malignant. These comprised 66 invasive, 26 in situ carcinomas and six other neoplasms. This latter group included one primary leiomyosarcoma, three cases of lymphoma, one case of metastatic renal cell carcinoma and one intramammary node with metastatic breast cancer. Of the remaining lesions 1083 have been established to be non-malignant (91.5%). A final diagnosis was not specified in the database for two lesions.
Fine needle aspiration biopsy was performed in 1149 cases (97.1%). Cytology was interpreted as benign in 882 cases (76.8%), atypical in 125 (10.9%), suspicious in 44 (3.9%), malignant in 43 lesions (3.7%) and inadequate in 55 (4.8%). FNAB was not performed in 32 cases, mostly because core biopsy was used as the initial method of assessment at the discretion of the assessment team. The morphology of three different lesions in this study, each assessed by FNAB and core biopsy, are depicted in , and .
Figure 2 Biopsy features of a case shown to be a fibroadenoma. (A) Low power photomicrograph of a fine needle aspiration biopsy of a discrete solid mass, showing mono-layered sheets of cohesive cells in a background of bipolar cells. (B) Cohesive sheet of cells (more ...)
Figure 3 Biopsy features of a fibroadenoma accompanied by a focus of high grade DCIS. (A) Low power view of a smear showing cohesive clusters of orderly cells (arrow), together with a dispersed population of large, atypical cells (left side of picture). (B) Higher (more ...)
Figure 4 Biopsy features of an intraductal papilloma. (A) Low power photomicrograph showing a highly cellular smear, composed of variable sized, cohesive clusters of orderly cells, numerous bare bipolar cells and some dissociated cells. (B) Higher power view of (more ...)
The correlation of the cytologic results against the final diagnosis is given in . Eight hundred and eighty of 882 (99.8%) lesions with benign cytology were benign. The two false-negative cases were both ductal carcinoma in situ (DCIS). In one case the cytology was interpreted as benign but some papillary features were noted. Since we recommend excision of papillary lesions, open biopsy was performed. This lesion was found to be a papillary and cribriform DCIS, eventually requiring mastectomy for complete excision. The second case had benign cytology. On excision for treatment of an adjoining higher grade lesion, the category 3 mass was found to comprise an area of fibrocystic change with a small focus of high grade DCIS. It is likely that the malignant focus in this mass was not sampled by FNAB.
Correlation of cytologic results against final diagnoses for the 1147 lesions assessed by fine needle aspiration biopsy
In all 40 of 42 lesions (95.2%) with malignant cytology were malignant, amounting to a false-positive rate of 4.8%. The cases with false-positive cytology were both intraductal papillomata. The likelihood of malignancy was 18.4% among lesions with atypical cytology and 63.6% for lesions with suspicious cytology. Among lesions that were ultimately proven to be benign, but had initially produced suspicious cytology, fibroadenoma was the commonest lesion (six cases), followed by reactive lymph nodes (three lesions), and one case of each of papilloma, hamartoma, usual ductal hyperplasia and atypical ductal hyperplasia.
Pattern of use of core biopsy
Core biopsy was used in 178 lesions in this series (15%). In 158 cases this followed FNAB. Core biopsy was required due to indefinite cytology in 126 cases comprising 35 cases with inadequate cytology, 69 with atypical cytology, and 22 with suspicious cytology. In 32 other cases core biopsy was performed to confirm positive cytology results (19 cases), or benign cytology results (13 cases) at the discretion of the assessment team. Core biopsy was the primary biopsy modality in remaining 20 cases.
shows the correlation between the core biopsy results and the final diagnosis. Core biopsy provided a definitive benign or malignant diagnosis in 79.8% of cases. One of 102 cases with benign core biopsy had positive cytology and was ultimately found to be malignant at surgery, the core being non-representative. The negative predictive value (NPV) of a benign core biopsy diagnosis was 99.0%. The positive predictive value (PPV) of a malignant core biopsy was 100%. The few cases with suspicious core biopsy findings were found to be malignant in 71.4% of cases and those with atypia on core biopsy were malignant in 7.1% of cases.
Correlation between core biopsy results and final diagnoses for the 178 lesions assessed by core biopsy
In 158 cases core biopsy followed cytologic assessment. shows these results. When core biopsy followed insufficient, atypical or suspicious FNAB, it established a definitive benign or malignant diagnosis in 77.8% of cases (98 of 126 cases). Core biopsy was positive for malignancy in 2.9% cases with inadequate cytology, 11.6% cases with atypical cytology, 50% of those following suspicious cytology and in 89.5% after positive cytology. In 19 cases with positive cytology, core biopsy was reported as malignant in 17 of these cases, suspicious in one case and benign in one case. Ultimately, all 19 lesions were indeed malignant, 17 invasive and two in situ carcinomas. Core biopsy was therefore helpful in distinguishing the two cases of DCIS from invasive cancers. The one case with benign core biopsy was a false negative due to a sampling problem. In no case with a prior benign cytologic diagnosis did core biopsy show malignancy.
Core biopsy after FNA biopsy
Overall, the core biopsy results were definitive in 79.8% of the cases: this included definite benign results in 57.3% of cases and a definite malignant diagnosis in 22.5%. The remaining 20.2% of cases had indefinite core biopsy results, including those with atypical, suspicious or nonrepresentative cores, all of which required further investigation.
Cases with final histologic diagnoses
Cases assessed with cytology are categorised according to the 5-tiered diagnostic system described above, but a specific tissue diagnosis is usually not possible in the majority of cases. A specific histologic diagnosis is available in the database in 271 lesions, principally from surgical specimens.
As shown in malignancy was documented in 98 of the discrete screen-detected masses in this series. Ductal carcinoma of no special type was the most common carcinoma, followed by mucinous carcinoma. Two tubular carcinomas and one case each of medullary and lobular carcinoma also presented in this manner. Among the malignant lesions there were three cases of lymphoma, one primary breast leimyosarcoma, one metastatic deposit of renal cell carcinoma to the breast parenchyma and one case of an intramammary node bearing metastatic breast cancer.
Final histology of selected lesions forming discrete masses on screening mammograms
Among the 66 invasive cancers, infiltrating ductal carcinoma of no special type constituted 74.2% of the lesions, while special type cancers together accounted for 25.8%. Grade I tumours were the most frequent cancer, accounting for 49.2% of the cases. Only 17.5% of the cancers were grade 3, and the remaining 33.3% were grade 2. Grade was not specified for three cases.
Of the 25 DCIS cases that presented as a discrete solid mass, only four were of high grade. Many of the DCIS cases in this series had a papillary component.
As we do not advise surgery for the vast majority of lesions found to be benign on biopsy, a specific histologic diagnosis is available in only a small proportion of these cases. As shown in , fibroadenoma was the most common benign diagnosis, followed by intraductal papilloma, fibrocystic changes, including ductal hyperplasia and inspissated cysts.
Phyllodes tumour was diagnosed through pathological assessment of the excised mass in seven lesions. Six of these were of the benign subtype and one case was a borderline lesion. There were no instances of malignant phyllodes tumour among this series of screen detected discrete category 3 mass lesions.
The records of the State Cancer Registry show that there was one interval cancer diagnosed within 27 months of the screening round of interest and that cancer affected the contralateral breast.
Tracking the clients with non-malignant findings during their subsequent rounds of screening showed that 781 of the 920 (84.9%) eligible women returned for subsequent rounds of screening. The mean period of follow-up was 54 months, (range 10.5–130.3 months). During this time seven women developed breast cancer, five invasive and two DCIS. As can be seen in , in seven of eight cases these cancers either affected the opposite breast or a different quadrant than the index lesion. The final case was a benign complex cyst on FNAB. Six years later microcalcifications were detected in the same quadrant during screening mammography. These were shown to be associated with DCIS of intermediate grade.
Cancers diagnosed in subsequent rounds of screening in women with benign discrete mass lesions