bjr_17982822

PICTORIAL REVIEW

Pregnancy-associated breast cancer: spectrum of imaging

appearances

A P AYYAPPAN, MD, S KULKARNI, MD and P CRYSTAL, MD

Breast Imaging, University Health Network & Mount Sinai Hospital, 600 University Avenue, Toronto M5G 1X5, Ontario,

Canada

ABSTRACT. Delay in diagnosis of pregnancy-associated breast cancer (PABC) iscommon, often attributed to the difficulty in evaluating tumours in the gravid breast,low awareness among physicians and reluctance of patients and physicians to performimaging or invasive procedures during pregnancy. Familiarity with imaging features ofPABC is crucial for prompt diagnosis. This article illustrates imaging findings of PABCand provides an approach for the evaluation of pregnant and lactating women withpalpable abnormalities.

Received 20 July 2009Revised 30 August 2009Accepted 2 October 2009

DOI: 10.1259/bjr/17982822

2010 The British Institute of

Radiology

Pregnancy-associated breast cancer (PABC) is definedas cancer diagnosed during pregnancy or in the first12 months post partum, or at any time while the patient islactating [1]. PABC is a rare but serious occurrencewith anincidence of approximately 0.3/1000 pregnancies [2]. Asmore and more women choose to delay childbearing untiltheir 30s or 40s, there may be an increase in the incidenceof PABC, as the proportion of pregnant women at anadvanced age who are already at a higher risk of breastcarcinoma increases. Around two-thirds of all PABC casesare diagnosed in the post-partum period, mostly in thefirst six months following delivery.The diagnosis of PABC is often delayed and remains

challenging because of underlying hormone-inducedanatomical and physiological changes occurring in breasttissue. The lack of awareness of PABC may precludetimely imaging or biopsy, leading to larger and moreadvanced neoplasms at diagnosis compared with age-matched non-PABC cases [3].The aim of this pictorial review is to increase

awareness of PABC by illustrating its imaging spectrum.This article also emphasises the importance of mammo-graphic and sonographic evaluation of pregnant andlactating women with palpable abnormalities.

Imaging approach in the pregnant or lactatingwomen with a palpable abnormality

Patients with PABC almost always present with apalpable mass [4]. Breast sonography is commonly theinitial imaging modality used for evaluating breastdisorders in women during pregnancy and lactation [4].

Mammography and ultrasound are essential comple-mentary modalities in imaging patients with palpableabnormalities. Immediate image-guided biopsy of sus-picious or indeterminate breast masses is necessary forprompt and accurate diagnosis. Theoretically, fine-needle aspiration (FNA) during pregnancy may beassociated with both increased false-positive andincreased false-negative rates [2]. Ultrasound guidedcore biopsy is the accepted cost-effective standardprocedure for assessing breast masses during pregnancyand lactation [4]. However, the decision to use corebiopsy requires caution because of increased risk ofbleeding, milk fistula formation and infection. Theserisks can be minimised by cessation of breastfeedingbefore core biopsy, paying close attention to haemostasis,and maintaining strict asepsis.

Imaging findings in women with PABC

Ultrasound

Ultrasound constitutes the most appropriate radiolo-gical method for evaluating breast disorders in womenduring pregnancy and lactation [4]. Breast sonographyhelps to determine whether the palpable area representsa true mass or normal parenchyma. The reportedsensitivity of sonography in the diagnosis of PABC is100% [5, 6]. Sonographic appearance can be useful indifferentiating benign from malignant breast masses. Innon-pregnant patients, sonographic Breast ImagingReporting and Data System (BI-RADS) descriptors suchas spiculated margin, irregular shape and non-parallelorientation has high predictive value for malignancy,whereas circumscribed margin, oval shape and parallelorientation are generally considered predictive of abenign diagnosis.Physiological changes associated with the breast and

lactation may alter typical sonographic features of breast

Address correspondence to: Dr Pavel Crystal, Staff Radiologist,Breast Imaging, Assistant Professor, University of Toronto,University Health Network and Mount Sinai Hospital, 600University Avenue, Toronto ON M5G 1X5, Canada. E-mail:[email protected]

The British Journal of Radiology, 83 (2010), 529534

The British Journal of Radiology, June 2010 529

carcinoma. Parallel orientation (Figure 1b) has beenreported in 58% of PABC [5]. Posterior acousticenhancement (Figures 2a and 3a) commonly seen inbenign breast lesions has been reported in 63% of PABCcases [5].PABCs are biologically aggressive neoplasms that may

outgrow their vascular supply, leading to necrosis orcystic degeneration (Figure 3a). Therefore, new palpablecomplex cystic masses identified during pregnancy andlactation warrant tissue sampling and should not bedisregarded as a galactocele or an abscess unless theseare clinically obvious.

Mammography

Bilateral mammography is recommended in pregnantand lactating women with clinical abnormalities. Mostauthorities believe that with the proper abdominal shield-ing two-view mammography poses very little risk ofradiation exposure to the fetus, as the radiation dose to thefoetus is negligible [4]. There is no concern about radiationdose in performing mammography on lactating women.The mammographic features of PABC do not differ from

those of non-PABC and include masses, microcalcifica-tions, asymmetrical density, architectural distortion and

(a) (b)

(c)

Figure 1. 40-year-old lactating woman, 6 months post partum, who presented with a palpable mass. Mastectomy revealed a4 cm triple-negative high-grade invasive ductal carcinoma with extensive high-grade ductal carcinoma in situ (DCIS). The patientdied 4 years after diagnosis. (a) Right mediolateral oblique mammogram shows a mass (arrow) with irregular margins. (b)Ultrasound image demonstrates a hypoechoic mass (arrows) with microlobulated margins, parallel orientation and adjacent skinthickening (star). (c) Post-contrast T1 weighted image shows strong enhancement of breast parenchyma (star) likely to hamperidentification of breast carcinoma (arrows).

A P Ayyappan, S Kulkarni and P Crystal

530 The British Journal of Radiology, June 2010

(a) (b)

(c) (d)

Figure 2. 39-year-old lactat-ing woman, 2 months postpartum, who presentedwith a clinical history ofbreast abscess. Ultrasound-guided biopsy revealedhigh-grade invasive ductalcarcinoma and high-gradeductal carcinoma in situ(DCIS). The patient under-went mastectomy afterneoadjuvant chemotherapy.The size of the largest focusof residual invasive carci-noma in the mastectomyspecimen was 5 mm. (a)Sonography reveals hypoe-choic solid mass (star) withangular margins and poster-ior acoustic enhancement(arrows). (b) Left mediolat-eral oblique mammogramwas performed after placinga clip (curved arrow) beforecommencing neoadjuvanttherapy. Carcinoma is mam-mographically occult. (c)Sagittal T1 weighted con-trast-enhanced MRI showsheterogeneously enhancingmass (star) and susceptibilityartefact (arrow) secondaryto the clip. (d) Sagittal T1weighted post-contrast MRimage following completionof neoadjuvant therapyshows no residual mass.

Pictorial review: Pregnancy-associated breast cancer


skin thickening (Figures 1a and 4a). The sensitivity ofmammography is that the diagnosis of PABC has beenreported to be 7890% despite dense breast parenchyma[5, 6]. Although a mass may not be discernible bymammography because of increased density of breasttissue, demonstration of microcalcifications, asymmetricaldensity, axillary lymphadenopathy or skin thickeningmighthelp in diagnosing PABC.

MRI

The routine use of contrast-enhanced MRI in theevaluation of pregnant patients is not appropriate and isrecommendedonly in situationswhere the riskbenefit ratiois clear. Contrast-enhanced MRI can be safely performed

during lactation. There is a paucity of data on MRI featuresof PABC. Espinosa et al [7] reported MRI findings of fivecases of breast carcinoma in lactating women. The MRIfeatures of cancer in lactating breast tissue are similar tothose of non-PABC cases and include homogeneously andheterogeneously enhancing masses (Figure 2c), mass withrim enhancement (Figure 3d), non-mass segmentalenhancement and diffuse unilateral enhancement.Unlike non-lactating breast tissue (Figure 5a), lactating

parenchyma (Figure 5b) shows rapid enhancement fol-lowing intravenous administration of contrast material,followed by an early plateau of enhancement, a featureattributed to increased vascular permeability similar tothat seen in invasive malignancy [7, 8]. Rapid enhance-ment of lactating parenchyma may hamper MRI detection

(a) (b)

(c) (d)

Figure 3. 35-year-old lactating woman, 4 months post partum, who presented with a palpable mass. Ultrasound-guided biopsyrevealed oestrogen receptor-negative and human epidermal growth factor 2 (HER2)-negative invasive ductal carcinoma. The patientunderwent mastectomy after neoadjuvant chemotherapy. Only microscopic residual disease was found in themastectomy specimen.The patient died 1 year after diagnosis. (a) Ultrasound image shows complex cystic mass with a thick irregular wall. (b) Axial T1weighted MRI image demonstrates large cystic mass with axillary lymphadenopathy (star). (c) Sagittal T2 weighted image shows ahyperintensemass with a thick irregular wall. (d) Post-contrast sagittal T1 weighted image shows otherwise unsupected small focus ofmalignancy (arrow) in addition to the index necrotic malignant mass (star) and axillary lymphadenopathy (curved arrow).



(a) (b)

Figure 4. 40-year-old lactating woman, 9 months post partum, who presented with an enlarged, firm breast, inverted nippleand peau dorange. Percutaneous ultrasound-guided biopsy revealed invasive ductal carcinoma and ductal carcinoma in situ(DCIS). Pre-operative imaging revealed bone and liver metastases. (a) Bilateral craniocaudal mammogram reveals extremelydense breast tissue. There is diffuse skin thickening (arrow) in the left breast. (b) Sagittal T1 weighted contrast-enhanced MRIdemonstrates multiple masses and diffuse breast enhancement along with pronounced skin thickening (star) findings areconsistent with inflammatory breast carcinoma.

(a) (b)

Figure 5. (a) Computer-generated kinetic curve (yellow dotted line) demonstrates minimal progressive enhancement of benignparenchyma in the left breast in a non-pregnant, non-lactating woman. The patient was diagnosed with progressivelyenhancing right breast ductal carcinoma in situ (red area of segmental enhancement with corresponding red line). (b)Computer-generated kinetic curve (red line) shows rapid enhancement of lactating breast parenchyma.

Pictorial review: Pregnancy-associated breast cancer


of malignancy (Figure 1c). Usually PABCs demonstrate afaster and greater degree of enhancement than lactatingtissue [7, 8]. MRImay be more reliable in depicting diseaseextent and multicentricity (Figures 2c, 3d and 4b).

Conclusion

The incidence of PABC may increase in the future asmore women postpone childbearing to middle age.Ultrasound is the initial imaging of choice for theassessment of palpable abnormality in pregnant andlactating women. Palpable solid and complex cysticmasses identified during pregnancy and lactation war-rant biopsy. Mammography and ultrasound are essentialcomplementary tests in women with palpable abnorm-alities and suspected PABC, as mammography detectsotherwise occult malignant microcalcifications. If a focallesion is not detected with mammography or sonogra-phy, a palpable suspicious mass should be biopsied.

References

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4. Sabate JM, Clotet M, Torrubia S, Gomez A, Guerrero R, delas Heras P, et al. Radiological evaluation of breast disordersrelated to pregnancy and lactation. Radiographics2007;27:S10124.

5. Ahn BY, Kim HH, Moon WK, Pisano ED, Kim HS, Cha ES, etal. Pregnancy- and lactation-associated breast cancer: mam-mographic and sonographic findings. J Ultrasound Med2003;22:4917.

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