Effective palliative, as well as curative, treatment is now available for patients with recurrent breast cancer. Optimal therapy is dependent on an accurate assessment of the location and extent of recurrent disease, which dramatically influences treatment decision making. Gene expression analysis has been used to identify patients at increased risk for distant recurrence.^1,2 There is also the suggestion that expression profiling may be helpful in identifying patients at greater risk for local recurrence.³ This information can potentially be used to tailor the frequency and types of imaging modalities used to monitor these patients.

Most often, the imaging assessment of recurrent disease extent requires use of both anatomic modalities, such as mammography, ultrasound, CT, and MRI, and molecular or metabolic imaging, utilizing positron emission tomography (PET) or combination PET/CT. While fluorodeoxyglucose (FDG) PET is a highly accurate method for evaluating the whole body for recurrence (both local and distant), anatomic and molecular imaging should be viewed as complementary. Hathaway and associates demonstrated the value of combining PET with MRI nearly a decade ago.⁴

The superb spatial resolution of CT and MRI is of great value in defining the size, shape, and precise location of suspected metastases, whether locoregional or distant. However, anatomically based imaging modalities may be suboptimal in separating active tumor from treatment-related changes. FDG PET can be very helpful in this situation. Additionally, whole-body PET can often change a patient’s stage; confirmation of local recurrence only may direct the treating physician toward a more aggressive, curative-intent approach (e.g., surgery, localized radiation, or both). One study showed that FDG PET changed the clinical stage in 36% of patients and led to a change in therapy in 58%.⁵

As with any tumor, knowledge of the typical biologic behavior and predictable sites of recurrence is helpful in focusing attention on specific regions. In patients treated with mastectomy, axillary node dissection, and chemotherapy, the most frequent sites of locoregional recurrence are the chest wall and supraclavicular nodes.⁶ Remote sites may include the mediastinum, internal mammary nodes, and most commonly, the skeleton.⁷

The following sites deserve comment with respect to appropriate imaging modalities for identification and characterization of disease recurrences: locoregional, brachial plexus, chest, bone, and distant metastases.

LOCOREGIONAL

Locoregional recurrence may occur in up to 22% of patients undergoing breast conservation surgery and radiation.⁸ Breast cancer 10-year local recurrence rates in women with negative surgical margins who undergo lumpectomy and radiotherapy may be as low as 10% or less.^9–12 Although overall recurrence rates are low, higher recurrence rates have been reported in select patient groups, such as those with high-grade ductal carcinoma in situ (DCIS).¹³ In addition, recurrence rates in younger women and in women who do not undergo radiation therapy have been reported as high as 35%.¹⁴

Despite the increasing utilization of accelerated partial breast irradiation, the long-term impact on recurrence rate for these newer techniques compared with whole breast irradiation is currently unknown. These techniques include interstitial radiotherapy with a multicatheter approach, intraoperative radiotherapy (IORT), using either electrons produced by linear accelerators or 50-kV x-rays (Intrabeam), the balloon-catheter technique (MammoSite), or three-dimensional conformal external-beam radiotherapy.

Serial surveillance mammography, as well as diagnostic mammography when there is clinical suspicion of breast recurrence, remains the cornerstone of the imaging approach to previously treated breast cancer patients (Figure 1). Complementary studies include breast ultrasound and MRI, as discussed in Chapter 3 (Figures 2 and 3). Cases presented in this chapter illustrate the spectrum of imaging manifestations of locally recurrent breast cancer.

FIGURE 1 Bilateral mediolateral oblique (MLO) mammograms, obtained in a 57-year-old woman 9 months after a pathologic diagnosis of DCIS was made from the right side of bilateral reduction mammoplasty specimens. New left supra-areolar masses are indicated by the arrow, and increased size and density were noted of left axillary lymph nodes.

FIGURE 2 Ultrasound of the same patient in Figure 1 shows one of multiple solid masses identified by ultrasound. This mass has particularly suspicious sonographic features: it is solid and irregularly marginated with no definable capsule, and a tail of suspected ductal extension can be seen extending to the right (arrow).

FIGURE 3 Contrast-enhanced axial breast MRI maximal intensity projection view of the same patient shows multiple intensely enhancing masses in the left subareolar region (arrow). Multifocal infiltrating ductal carcinoma was confirmed at subsequent mastectomy.

Local failure most commonly occurs in or near the lumpectomy bed, in the same quadrant, and may manifest in a manner similar to the initial presentation (e.g., microcalcifications developing where calcified DCIS has previously been treated). Such changes arising in a lumpectomy bed under surveillance need careful analysis, such as with magnification views, to differentiate from similar-appearing, treatment-related changes (e.g., calcification due to fat necrosis). In some cases, differentiation based on morphology may not be possible, and tissue sampling will be required.

In general, surgical scars are expected to contract over time. Post–partial mastectomy scars should be carefully scrutinized on follow-up mammograms for increased size or density, which may signify recurrent disease. Scar enhancement can be expected on MRI in the first year after surgery and radiation therapy, but should decline in intensity over time, and little enhancement should be seen by about 18 months after treatment. More than 18 months after breast conservation therapy, MRI can be very helpful in differentiating postoperative scarring from recurrence, with scars expected to show little, if any, enhancement, unlike most recurrent tumor masses.

Palpable lumps developing in the breast, axilla, or chest wall of a patient previously treated for breast cancer raise the specter of recurrent disease, but not infrequently are due to treatment-related mimics, such as fat necrosis masses. Depending on location, these can be evaluated with some combination of mammography, ultrasound, and tissue sampling. At times, such mimics are sufficiently characteristic that imaging alone can make the diagnosis, but histologic sampling may be necessary for confirmation.

Mammographic follow-up is warranted in patients who have undergone subcutaneous mastectomy because of the considerable amount of remaining breast tissue. The yield from mammographic surveillance of the breast after standard mastectomy or skin-sparing mastectomy and reconstruction has been questioned. Because most recurrences occur in the skin and subcutaneous tissues, they can usually be detected on physical examination. The overall annual recurrence rate of T1 or T2 tumors following mastectomy has been reported to be 1% to 2% during the first 5 years.¹⁵ Annual mammographic evaluation following mastectomy and transverse rectus abdominis musculocutaneous (TRAM) flap reconstruction has been advocated to screen for any residual breast tissue and to detect recurrences before they are palpable.¹⁶

The timing for mammographic follow-up after breast conserving therapy has not been standardized. At a minimum, a 6-month follow-up mammogram should be performed to establish the patient’s baseline after surgery. The incidence of a recurrence in the ipsilateral breast 20 years after surgery is 14.3% among women who undergo irradiation after lumpectomy and 39.2% among those who undergo lumpectomy without irradiation.¹⁷

Larger-field-of-view anatomic modalities, such as CT and MRI, are often more suitable to assess suspected chest wall or supraclavicular abnormalities. Because a growing number of patients with locally recurrent disease are being treated with curative intent, whole-body PET is recommended to confirm active tumor at sites identified as abnormal or suspicious with CT or MRI, and to search for distant metastases. Upstaging or downstaging may influence the choice of therapy.

A 36-year-old woman noted a palpable right upper outer quadrant (UOQ) breast mass. Breast imaging evaluations showed a corresponding 1-cm hypoechoic, solid, vascular, sonographically indeterminate breast mass. Ultrasound-guided biopsy identified infiltrating ductal carcinoma (IDC) (Figure 1).

FIGURE 1 Ultrasound of the palpable right UOQ lump identified a lobular, solid, wider-than-tall mass. Two concerning features are depicted here: increased vascularity and angular margins (note upper right border of the mass, the morphology of which suggests ductal extension).

The past medical history was notable for prior mantle radiation for Hodgkin’s disease 12 years before. Preoperative breast MRI evaluation showed the known IDC as a 1.1-cm, early enhancing mass with washout, with a 4-mm suspected satellite nodule adjacent. A separate, lobular 5 × 3-mm possible intramammary lymph node was noted in the lateral breast. The left breast showed no focal or concerning findings (Figures 2 and 3).

FIGURE 2 Axial maximal intensity projection (MIP) from enhanced, dynamic breast MRI series, 1 minute after contrast injection, shows three early enhancing right breast nodules. Two are adjacent in the posterior lateral breast and correspond to the ultrasound. The separate, more anterior lateral focus was hyperintense on STIR, suggesting a possible small intramammary lymph node or fibroadenoma.

FIGURE 3 Axial MIP from enhanced dynamic breast MRI series, 2 minutes after contrast injection, shows washout of the largest mass. There is also loss of conspicuity due to progressive breast parenchymal enhancement.

The patient elected to undergo bilateral mastectomies, with tissue expanders placed. The right mastectomy specimen contained a 0.9-cm IDC, with high-grade ductal carcinoma in situ (DCIS) extending 5 mm beyond the invasive carcinoma, estrogen receptor negative, HER-2/neu negative. Atypical ductal hyperplasia was identified in multiple quadrants, as well as found in the left mastectomy specimen. The margins were negative. Four right axillary lymph nodes showed no evidence of disease.

Staging evaluations with positron emission tomography (PET) and CT obtained before chemotherapy showed chest wall changes attributable to surgery, as well as normal variant endometrial activity (Figures 4, 5, and 6).

FIGURE 4 Axial PET/CT images, obtained for systemic staging after bilateral mastectomy (left prophylactic) and tissue expander placements, show symmetrical increased anterior chest wall uptake.

FIGURE 5 Corresponding enhanced chest CT images (A to C, from above to below), for correlation with PET, showing postoperative changes from recent bilateral mastectomy, with tissue expander placements. Symmetrical skin thickening and induration are noted of the anterior chest wall. Tissue expanders are usually positioned so that the upper two thirds are below the pectoral muscle. The integrated port can be seen on the left in B, and on the right in C.

FIGURE 6 Sagittal PET/CT images show linear increased metabolic activity in the pelvis, localizing to the endometrial lining.

TEACHING POINTS

Younger patients treated for lymphoma with mantle radiation are at increased risk for a second malignancy (the incidence is 10% to 20% at 20 years of follow-up). Mantle radiation includes the neck, supraclavicular, infraclavicular, axillary, mediastinal, and hilar regions (Figure 7). The unshielded upper outer quadrants of the breasts receive the highest doses.

FIGURE 7 Mantle field radiation encompasses the nodal basins in the neck, supraclavicular and infraclavicular regions, axilla, mediastinum, and hila.

From Estabrook A, Giron G. Treatment of unusual malignant neoplasias and clinical presentations. In Roses DF (ed): Breast Cancer, 2nd ed. Philadelphia: Churchill Livingstone, 2005, p 705.

In women, if a second malignancy develops, it is most commonly breast cancer.

Travis and colleagues found 105 cases of breast cancer in a series of 3817 females treated for Hodgkin’s disease before the age of 30 years. The risk is dose dependent, and the highest risk is in those treated in adolescence (ages 10 to 20 years). Presumably, the breast tissue is most susceptible to radiation injury during earlier development.

In such patients, breast conservation therapy is often not an option because repeat radiation may not be possible.

The normal, early postoperative findings of mastectomy with tissue expander placement are demonstrated here. A described, normal variant source of fluorodeoxyglucose (FDG) activity on whole-body PET is also seen here in the pelvis. Endometrial activity is most commonly seen in premenopausal patients during the first (menstruation) or third (ovulation) week of the menstrual cycle. If endometrial activity is identified on PET in a postmenopausal patient, this warrants further investigation, because endometrial carcinoma can manifest this way.

A 38-year-old woman elected to undergo prophylactic left mastectomy and bilateral transverse rectus abdominis musculocutaneous (TRAM) flap reconstruction 10 months after finishing radiation therapy for a right stage II, T2N1, 3-cm infiltrating ductal carcinoma (IDC), estrogen receptor and progesterone receptor negative, and HER-2/neu negative-, with 3 of 22 involved axillary lymph nodes. She had been treated with right mastec-tomy with clear margins, chemotherapy with four cycles of doxorubicin (Adriamycin) and cyclophosphamide (Cytoxan) (AC) and four cycles of paclitaxel (Taxol), and right chest wall, supraclavicular, and posterior axillary boost radiation therapy (see Case 18 in Chapter 3 for the presenting imaging features and initial staging of this patient).

The patient had undergone genetic testing subsequent to her diagnosis and treatment and proved to be BRCA-1 positive. Her family history was of premenopausal breast cancer in a maternal aunt. As a consequence, she decided to undergo hysterectomy and oophorectomy, which was performed at the same time as prophylactic left mastectomy and bilateral TRAM flap reconstruction (Figures 1, 2, and 3). Her left breast mastectomy specimen was benign.

FIGURE 1 Enhanced chest CT images (A, above; B, below) show typical changes of bilateral TRAM flap reconstruction after bilateral mastectomy. This study was obtained 3 weeks after surgery. The reconstructed breasts are fatty. Thin, soft tissue density, curvilinear bands can be seen underneath and parallel to the skin surface of the reconstructed breasts. On the right, this is best seen in A, and on the left, in B (arrows). This thin line represents the de-epithelialized abdominal wall skin of the flap, which has been tunneled up into position from the abdomen. The fat overlying this thin line is part of the native chest wall, and the fat deep to this line is abdominal wall fat transposed with the flap.

FIGURE 2 At the level of the epigastrium, usually at the level of the fifth, sixth, or seventh costal cartilages, the tunneled rectus muscles are visualized paralleling the costal margin. They can be expected to atrophy with time.

FIGURE 3 Drawing illustrates bilateral ipsilateral TRAM flap breast reconstruction. In this procedure, a large ellipse of lower abdominal fat and skin, including the rectus abdominis muscle, is obtained with a transverse abdominal incision. This flap is transposed to the chest by tunneling underneath the anterior chest wall. The flap remains attached to the rectus muscle, which provides the blood supply.

The patient’s postoperative course was complicated by development of abdominal wound infection (Figure 4), requiring débridement twice of infected, necrotic tissue and intravenous antibiotic therapy, as well as anticoagulation for pulmonary embolism.

FIGURE 4 Enhanced abdominal CT images (A, above; B, below), 3 weeks after surgery, show changes from infection and necrosis of the abdominal wound. At this point, the patient’s abdominal wall wound was 3 days post débridement of infected necrotic tissue. Air and an elliptical abdominal wall fluid collection are seen in A, with strandy induration of the anterior abdominal wall and an open wound seen more inferiorly in B. Note absence of the rectus muscles in B.

A 51-year-old woman, with prior left breast ductal carcinoma in situ (DCIS) treated with lumpectomy only, underwent annual screening MRI. The MRI demonstrated a developing 1.2-cm focal area of enhancement in the left breast, lateral to the patient’s prior lumpectomy site (Figures 1 and 2). Mammography showed no abnormality. Ultrasound demonstrated a small area of altered echotexture that appeared to correspond to the abnormal finding on MRI (Figure 3). Ultrasound-guided core needle biopsy identified intermediate-grade DCIS. The patient was treated with surgical excision and radiation therapy.

FIGURE 1 Postcontrast, subtracted, axial MRI demonstrates a developing 1.2-cm area of abnormal, irregularly marginated mass enhancement in the left breast, lateral to the patient’s prior lumpectomy (arrow).

FIGURE 2 Postcontrast, subtracted, axial MRI, 1 year before, for comparison. No suspicious areas of enhancement are seen. There are a few tiny, benign-appearing, scattered foci of enhancement. Vague, low-level focal enhancement is seen on the left laterally, where the suspicious abnormality developed on the following year’s exam.

FIGURE 3 Ultrasound images (A and B) of the lateral left breast demonstrate a subtle area of altered echotexture (arrows). This appeared to correspond in size, shape, and location to the enhancing mass seen on MRI. This finding was just lateral to the scar from prior lumpectomy. Ultrasound-guided core needle biopsy confirmed intermediate grade DCIS.

A 48-year-old woman, 3 years post-mastectomy and chemotherapy for a right stage I invasive ductal breast cancer, developed a small, 0.5-cm, firm nodule lateral to the nipple tattoo of her reconstructed breast. Her original tumor was a T1N0 lesion, estrogen receptor positive and HER-2/neu negative. She had been treated with four cycles of doxorubicin (Adriamycin) plus cyclophosphamide (Cytoxan) (AC), and had been taking tamoxifen since.

Ultrasound showed a 6-mm, irregularly marginated mass, disrupting the normal architecture planes (Figure 1). This was surgically excised, identifying recurrent infiltrating ductal carcinoma (IDC), estrogen receptor and progesterone receptor positive and HER-2/neu negative, involving the subcutaneous adipose tissue and skeletal muscle of the chest wall.

FIGURE 1 Ultrasound of the palpable lump shows a superficial, sonographically suspicious mass with irregular margins and disruption of tissue planes (arrow). The patient is post-mastectomy, with implant reconstruction. The sonolucent implant is seen beneath the mass.

Staging evaluations with positron emission tomography (PET)/CT and bone scan showed no additional sites of recurrent breast cancer. The patient underwent excision, with removal of the implant, and axillary dissection. No residual cancer was found in the breast, and 1 of 11 lymph nodes showed involvement (largest focus was 0.8 cm).

Chemotherapy with docetaxel (Taxotere) and capecitabine (Xeloda) was given, and the patient was treated additionally with right chest wall, supraclavicular, and posterior axillary boost radiation.

TEACHING POINTS

Implants hamper mammographic evaluation of breast tissue. However, the stretching and thinning of breast tissue over an implant can actually make lumps more easily palpable and can aid sonographic evaluation as well (Figure 2).

FIGURE 2 Comparison of palpation of a lump in a non-augmented breast (left) vs. in an augmented breast (right): The presence of an implant thins the overlying tissue and may make a lump more readily palpable.

The sonographic appearance of this small mass was certainly suspicious: it is as tall as wide, with irregular margins and disruption of tissue planes. Of course, not every new, suspicious sonographic mass developing in a patient with previous breast cancer represents recurrent breast cancer. See Figure 3 (Case 9 in Chapter 7) for a very similar-appearing finding that proved to be fibrosis and foreign body giant cell reaction in a previously treated breast cancer patient with recently placed implants.

FIGURE 3 Ultrasound of a palpable periareolar mass in another patient, a 54-year-old woman, treated 10 years before with partial mastectomy, radiation therapy, six courses of Cytoxan, methotrexate, 5-fluorouracil (CMF) chemotherapy, and 5 years of tamoxifen, for T1cN1M0, left breast IDC. Bilateral, subpectoral implants had been placed in the past year. A very hypoechoic, taller-than-wide, irregularly marginated mass was biopsied with ultrasound guidance, with 14-gauge core biopsy technique. Pathology showed no carcinoma, with sclerosis, fibrosis, and foreign body giant cell reaction found.

A 68-year-old woman, 5 years after left breast mastectomy and transverse rectus abdominis musculocutaneous (TRAM) flap reconstruction, presented with a palpable mass at the lateral aspect of the left TRAM reconstruction (Figure 1). Subsequent core needle biopsy confirmed recurrent infiltrating ductal carcinoma.

FIGURE 1 CC (A) and laterally exaggerated CC (B) mammographic views demonstrate an ill-defined dense mass involving the posterior lateral aspect of the left neo-breast (arrows). This corresponded to the patient’s palpable finding.

A 54-year-old woman presented with a palpable mass within the upper outer right breast. The patient was referred to a surgeon for evaluation. Needle biopsy of the palpable mass revealed ductal carcinoma in situ (DCIS). The patient underwent a preoperative MRI, which demonstrated an extensive area of enhancement in the lateral right breast, suggesting extensive intraductal disease (Figure 1). Mammography and ultrasound failed to demonstrate with certainty the extensive findings seen on MRI. Therefore, MRI-guided biopsy was performed for surgical planning to establish the extent of disease (Figure 2). The MRI-guided biopsy of a site distant to the known right DCIS confirmed additional DCIS. Because of this, the patient underwent right mastectomy with transverse rectus abdominis musculocutaneous (TRAM) flap reconstruction. Pathology showed close margins for the mastectomy specimen. Six months later, the patient had a follow-up MRI that was interpreted as normal (Figure 3). On mammography 1 year after mastectomy, the small marker clip from MRI biopsy was noted in the lateral aspect of the TRAM flap (Figure 4). Ultrasound evaluation of the area of the clip demonstrated multiple small nodules (Figure 5). Core needle biopsy revealed both DCIS and invasive ductal carcinoma. The patient was treated with surgical resection and radiation therapy.

FIGURE 1 Postcontrast subtracted, maximum intensity projection MRI. MRI demonstrates a diffuse segmental area of enhancement involving a large portion of the lateral right breast. In a patient with known right DCIS, these findings are highly suspicious for extensive intraductal carcinoma. Extensive background fibrocystic enhancement is noted bilaterally.

FIGURE 2 Postcontrast axial biopsy MRI of the right breast. MRI-guided biopsy was performed to confirm the extent of the patient’s disease. The tip of the biopsy needle (arrow) is seen traversing the area of enhancement from a lateral approach. Following the biopsy, a metallic marker clip was placed in the biopsy cavity.

FIGURE 3 Fat-saturated, postcontrast delayed MRI obtained 6 months after the patient’s right mastectomy and TRAM flap reconstruction was interpreted at the time as normal. However, in retrospect, a small area of enhancement is seen in the lateral aspect of the TRAM flap reconstructed right breast (arrow).

FIGURE 4 Right MLO (A) and CC (B) mammographic views. The right breast demonstrates changes consistent with mastectomy and TRAM reconstruction. However, a small metallic marker clip is seen in the upper outer neo-breast (arrows). This is the marker clip from the prior MRI-guided biopsy, performed at the time of initial diagnosis of DCIS.

FIGURE 5 Ultrasound image of the TRAM flap. Within the area of the clip, in the lateral TRAM flap reconstructed breast, are demonstrated several small hypoechoic nodules aligned in a ductal orientation (arrows).

A 57-year-old woman was suspected to have recurrent breast cancer, based on palpable left supraclavicular adenopathy, 2 years after left mastectomy and TRAM flap reconstruction for recurrent left breast cancer. Her original cancer had been a poorly differentiated, stage 1, node-negative, estrogen receptor– and progesterone receptor–negative tumor, which was treated with lumpectomy, four cycles of doxorubicin (Adriamycin) plus cyclophosphamide (Cytoxan) (AC) and radiation therapy 2.5 years before recurring.

Two years after undergoing mastectomy and TRAM flap reconstruction, the patient was noted on physical examination to have a 2-cm firm left supraclavicular lymph node. It was confirmed by MRI (Figure 1). Referral to an ear, nose, and throat specialist for fine-needle aspiration (FNA) resulted in development of arm paresthesias during the procedure, which was stopped. The patient was later referred for CT-guided biopsy. This obtained a fragment of a benign lymph node, with no morphologic evidence of metastatic carcinoma. The patient was followed clinically, and underwent positron emission tomography (PET)/CT about 1.5 years after the lymph node was first noted. Two hypermetabolic foci were identified on PET/CT, one in the reconstructed neo-breast and one corresponding with the left supraclavicular node (Figures 2, 3, 4, and 5). The findings were interpreted as consistent with recurrent breast malignancy. Breast MRI was obtained subsequently and showed a rim-enhancing mass with fatty and soft tissue elements at the posterior aspect of the reconstructed breast (Figure 6). This was thought to be secondary to the TRAM flap surgery, with fat necrosis. The patient had not had a mammogram since the surgery, so mammography was obtained for correlation (Figures 7 and 8). This showed rim and coarse fat necrosis–type calcifications (CT images provided for correlation, Figures 9 and 10). Subsequent ultrasound-guided biopsy confirmed fat necrosis with dense fibrosis and calcification (Figure 11). The left supraclavicular lymph node was excised, was benign, with nonspecific granulomatous lymphadenitis, and presumably was reactive and secondary to the breast process.

FIGURE 1 T1-weighted (A) and STIR (B) coronal images from an MRI of the neck soft tissues show a small round left supraclavicular lymph node (arrow), which was initially detected by palpation.

FIGURE 2 Axial images (two levels, A and B) from PET/CT (upper left: CT; upper right: non-attenuation-corrected (NAC) PET; lower left: fused PET/CT; lower right: CT attenuation-corrected PET) through the breasts. The left breast has been reconstructed postmastectomy, using a TRAM flap. At the posterior aspect of the neo-breast, a whorl of fat with surrounding soft tissue rind and coarse calcifications is seen. Hypermetabolism is seen, which localizes to the coarsely calcifying components. This appears more linear in (A) and more focal below (B).

FIGURE 3 Coronal (A) and sagittal (B) views through the focal activity within the left neo-breast.

(from left to right: CT, PET, fused PET/CT, NAC PET).

FIGURE 4 Coronal PET/CT slice shows the small, hypermetabolic left supraclavicular lymph node.

FIGURE 5 Axial section from a contrast-enhanced CT scan at the supraclavicular level shows two adjacent, mildly enlarged lymph nodes.

FIGURE 6 Axial images from breast MRI include T2-weighted (A); STIR (B); enhanced, subtracted T1-weighted, gradient echo (C and D); and maximal intensity projection (MIP) (E) images. A and B, T2-weighted and STIR images show a lobular, predominantly fatty signal mass at the posterior aspect of the left neo-breast, with a smooth, thick, hypointense rim. C and D, Enhanced, subtracted, T1-weighted, gradient echo slices show no significant interior enhancement of the fatty portion of the mass, with smooth, rim enhancement only. E, Axial MIP view of a three-dimensional data set from the dynamic enhanced series is misleading and illustrates why MIPs should never be relied on for primary diagnoses. They provide an overview only. In this case, the rim-enhancing fat necrosis mass is summated, and it appears here as a more extensively enhancing mass.

FIGURE 7 MLO (A) and CC (B) mammograms show the fatty composition of the reconstructed left neo-breast. Dense calcification is mass-like overlying the pectoral muscle on the left, posteriorly and superiorly on the MLO view (asterisk).

FIGURE 8 Detail view (exaggerated CC view) of the left breast calcification shows it to be coarse, shell-like, and dystrophic.

FIGURE 9 Corresponding CT images (A and B) show a lobular, centrally fatty mass in the upper reconstructed left breast, with thick soft tissue density rim and coarse peripheral calcifications.

FIGURE 10 A section through the inferior left neo-breast shows a more typical, uncomplicated TRAM flap appearance, being essentially completely fatty, with the atrophied rectus muscle flap against the chest wall, with minimal asymmetry compared with the native right chest wall.

FIGURE 11 Sonography of the fat necrosis mass in the left neo-breast shows it to be lobular, solid, and very heterogeneous, with hyperechoic and hypoechoic components.

A 72-year-old woman, 7 years after treatment with lumpectomy and radiation therapy for left breast infiltrating ductal carcinoma, underwent annual screening MRI. The MRI demonstrated an abnormal area of enhancement involving the anterior chest wall, suspicious for chest wall recurrence (Figure 1). CT and positron emission tomography (PET) scans were performed to further evaluate the finding. The CT scan confirmed the findings (Figure 2), and the PET scan showed increased uptake of the abnormality (Figure 3). Subsequent needle biopsy confirmed the suspected diagnosis of chest wall recurrence, and the patient was treated with radiation therapy.

FIGURE 1 Postcontrast, subtracted, axial MRI demonstrates an ill-defined geographic area of enhancement in the left anterior chest wall, extending into the anterior mediastinum (arrow).

FIGURE 2 Postcontrast CT confirms an abnormal area of soft tissue density in the left anterior mediastinum, involving the anterior chest wall (arrow), corresponding to the finding on MRI.

FIGURE 3 Sagittal projection PET volume image. Within the anterior chest wall is an area of focally increased uptake (arrow) that corresponds to the area seen on MRI and CT. Together, the findings are highly suspicious for chest wall recurrence.

CASE 18 Recurrent IDC and radiation-induced pleomorphic sarcoma, with chest wall invasion^*

A 79-year-old woman noted a change in the appearance of her right breast for several months. She was 5 years post–breast conservation therapy for a stage I, T1N0, 1.2-cm poorly differentiated infiltrating ductal carcinoma (IDC), estrogen receptor and progesterone receptor positive, HER-2/neu negative, with five negative lymph nodes. She had been taking tamoxifen and later anastrozole (Arimidex).

On physical examination, the right lateral breast was indurated and fixed to the chest wall. Her mammogram showed suspicious increased density deep to the level of her scar (Figures 1, 2, and 3). Ultrasound showed a corresponding, heterogeneous, hypoechoic mass with irregular margins (Figure 4). Ultrasound-guided core needle biopsy showed recurrent ductal carcinoma and a very atypical spindle cell proliferation, with atypia in excess of that expected from radiation damage. This component was thought to be a pleomorphic sarcoma, probably radiation induced.

FIGURE 1 MLO (A) and CC (B) mammograms show the previously treated right breast to be smaller than the left. New increased density seen in the deep lateral right breast, subjacent to the scar level, is not visualized in its entirety. Right axillary surgical clips from prior dissection are noted.

FIGURE 2 MLO (A) and CC (B) mammograms from 2 years earlier with scar markers delineating the area of prior lumpectomy.

FIGURE 3 MLO (A) and CC (B) comparison mammograms from 1 year earlier show developing density in the right posterior lateral breast, included only on the CC view.

FIGURE 4 Breast sonogram shows a hypoechoic mass with posterior shadowing and irregular margins in the right lateral breast, corresponding to the mammographic abnormality.

Subsequent evaluations included breast MRI; chest, abdomen, and pelvis CT scans; and positron emission tomography (PET)/CT. The breast MRI showed the mass to be large, with rim enhancement and washout. The mass penetrated and invaded the chest wall and was accompanied by a large internal mammary lymph node (Figures 5, 6, 7, and 8). Both the mass and the internal mammary lymph node were intensely hypermetabolic on PET, as was a right lower lobe nodule (Figure 9).

FIGURE 5 Enhanced, subtracted, axial breast MRI view of both breasts shows a lobular mass in the right posterior lateral breast, with intense rim enhancement. The mass traverses the chest wall and extends into the chest.

FIGURE 6 Axial T1-weighted (A) and STIR (B) views of the mass show it to be hypointense on T1 and mildly hyperintense on STIR. The right breast skin is thickened, and there is diffuse edema and reticulation of the breast. Although these findings are expected with prior radiation, the changes are more than generally seen 5 years after treatment. This suggests lymphedema from obstructed lymphatics as a potential alternative explanation.

FIGURE 7 Axial STIR (A) and enhanced, subtracted, T1-weighted gradient echo (B) MRI views show an enlarged right internal mammary lymph node. Its enhancement is peripheral, similar to the primary, suggesting central necrosis.

FIGURE 8 Adjacent T1-weighted, coronal MRIs of the thorax (A anterior to B) show the enlarged right internal mammary (IM) lymph node adjacent to the IM vessels (asterisk). The lobular primary mass (M) infiltrates chest wall muscle.

FIGURE 9 Axial fused PET/CT and PET images show intense hypermetabolism of the right breast mass, extending through the chest wall, and in a right lower lobe lung metastasis.