Breast microcalcifications: the UK RCR 5-point breast imaging system or BI-RADS; which is the better predictor of malignancy?

Abstract

Objective: In the UK RCR 5-point breast imaging system (UKS), radiologists grade mammograms from 1 to 5 according to suspicion for malignancy, however unlike BI-RADS, no lexicon of descriptors is published. The aim of this study was to determine whether strict categorisation of microcalcifications (MCC) according to BI-RADS was a better predictor of malignancy than the UKS and whether these descriptors could be used within the UKS. Methods: A retrospective review of 241 cases, with MCC on mammography, who underwent biopsy was performed. Morphology, distribution, extent, UKS score, BI-RADS category and pathology were recorded. The positive predictive value (PPV) of each classification system for malignancy was calculated. Results: 28.6% were diagnosed with DCIS/IDC. The PPV for malignancy using the UKS was 18.9%, 69.4%, 100% for M3-5 respectively (p < 0.001) and using ΒI-RADS morphology was amorphous: 7.1%, coarse heterogeneous: 33.3%, fine pleomorphic: 48.1% and fine linear/fine linear branching: 85.2% (p < 0.001). The PPV based on distribution was grouped: 14.2%, regional: 32.3%, diffuse: 33.3% and linear/segmental: 77.8% (p < 0.001). Combining all cases of benign-appearing, amorphous and grouped coarse heterogenous and grouped fine pleomorphic MCC gave a PPV of 12.8%. Combining regional, linear or segmental coarse heterogenous and fine pleomorphic and all fine linear/branching MCC resulted in a PPV of 83.3% for malignancy. Conclusion: Combining morphology and distribution of MCC is accurate in malignancy prediction. Use of BI-RADS descriptors could help standardise reporting within the UKS and an algorithm using these within the UKS is proposed. Better prediction would enable more appropriate counselling and help to identify discrepancies. Advances in knowledge: No guidance exists on scoring of suspicious MCC in the UK breast imaging system. Use of BI-RADS morphologic/distribution descriptors can aid malignancy prediction. Findings other than morphology of MCC are important in malignancy prediction. An algorithm for use by the UK radiologist when evaluating MCC is provided.

Patterns of aggressiveness: risk of progression to invasive breast cancer by mammographic features of calcifications in screen-detected ductal carcinoma in situ

“…Morphology and distribution of calcifications on screening mammograms are predictors of malignancy existence (13)(14)(15). Further, risk of diagnostic upstaging to invasive breast cancer among women who had a core needle biopsy with DCIS was associated with preoperative mammographic features (16)(17)(18)(19)(20).…”

Amorphous breast calcifications: is BI-RADS 4a appropriate?

“…Although the rate of detection of amorphous calcifications has increased with the use of digital mammography and specific medical monitors, the management of this subgroup of calcifications can be challenging. It is not uncommon for amorphous calcifications to be identified only on magnified images, in only one view, or even not defined in the stereotactic window on stereotaxic devices or tables, making it impossible to perform percutaneous biopsy or the preoperative marking process ( 4 , 5 , 6 , 7 , 8 , 9 ) .…”

Calcificações amorfas: devemos nos preocupar com elas?

“…Encontramos no nosso estudo um VPP para malignidade de calcificações amorfas de 9,42%, sendo diagnosticadas 13 lesões malignas dentre as 138 calcificações biopsiadas. Kim et al (8) e Metaxa et al (17) , evidenciaram VPPs de 7,9% e 7,1% respectivamente e os estudos de Oligane et al (4) , e Ferreira et al (16) , VPPs de 10,5% e 10,3% respectivamente, valores próximos ao encontrado em nosso trabalho. O estudo de Iwanse et al (9) obteve um VPP mais baixo (2,8%) para calcificações amorfas, sugerindo possível seguimento mamográfico em detrimento de biópsia, porém a maioria das pacientes do estudo não tiveram comprovação histopatológica do achado mamográfico (71,4%), sendo os grupamentos de calcificações amorfas com estabilidade de 24 meses foram considerados como benignos, o que pode ter subestimado o número de lesões malignas, principalmente carcinomas ductais in situ de crescimento insidioso.…”

“…Tabela 5 -Tabela de valores preditivos positivos para malignidade das calcificações amorfas nos principais estudos publicados (4,5,8,9,16,17) .…”

“…Iwanse et al 2016 (9) Kim et al 2015 (8) Metaxa et al 2019 (17) Ferreira et al 2018 (16) Oligane et al 2018 (4) Park et al 2019 (5) 2,8% (n=216) Nosso estudo evidenciou um maior número de diagnósticos de carcinomas invasivos (53,84%) em relação a CDIS (46,15%), diferentemente dos dados encontrados por outros autores (4,5,8,9,13,17,18) . Esta diferença pode ser parcialmente explicada pelo número reduzido de neoplasias malignas encontradas (13/138) no nosso trabalho.…”