Benign papillary neoplasms of the breast: mammographic findings

The clinical presentation, pathologic characteristics, and mammographic/ductographic (also known as galactographic) findings were reviewed in 77 patients with histologically proved benign papillary neoplasms of the breast. Patients were classified as having either solitary or multiple papillomas. Patients with multiple papillomas were further subclassified as having either central or peripheral papillomas. Fifty-one patients (66%) had solitary papillomas. Thirty-seven of these patients were symptomatic; 36 had spontaneous nipple discharge, and one had a palpable mass. Ductography was positive in 32 of the 35 patients who underwent the procedure. In the 14 asymptomatic patients, subareolar (n = 10) and peripheral (n = 4) mammographic abnormalities prompted biopsy. Fourteen patients (18%) had multiple peripheral papillomas, and one patient also had bilateral central solitary papillomas. Eleven of these patients were asymptomatic, while two presented with palpable abnormalities and one with spontaneous bilateral discharge. Mammographic findings included microcalcifications (n = 5) and clustering nodules (n = 2). Associated atypical ductal hyperplasia was found in six (43%) of the 14 patients with multiple peripheral papillomas. Some of these patients also had lobular carcinoma in situ and radical scars. Twelve patients had multiple central papillomas; all presented with spontaneous nipple discharge and had positive ductograms.     

Radiological appearances of papillary breast lesions

This review illustrates the varied appearances of benign and malignant papillary breast tumours, as identified by a breast cancer-screening programme. The commonest mammographic appearance of a papillary tumour is as a soft-tissue mass, with calcification present in less than half of cases. When calcification is present the pattern is variable, but clusters of pleomorphic calcification can occur, sometimes resembling the mammographic appearance of invasive ductal carcinoma. Ultrasonography of papillary lesions typically shows a solid, oval, intraductal mass, often associated with duct dilatation. A cystic component is also commonly seen, and lesions may appear hypervascular on colour Doppler ultrasound. Magnetic resonance imaging (MRI) has a high sensitivity, but low specificity for detecting papillary tumours, and is useful in establishing the extent and distribution of lesions in patients with multiple papillomatosis. Despite a benign histology on core biopsy, an argument exists for complete surgical excision of all papillary tumours, as a significant proportion of papillomas will contain foci of atypia or overt malignant change.     

Invasive papillary carcinoma of the breast: mammographic appearance

The mammographic findings in 18 patients with invasive papillary carcinoma were studied retrospectively. The mammograms of 10 patients showed a multinodular pattern, and seven patients had solitary nodules. One patient had an irregular, ill-defined mass in the retroareolar region. Two patients were found to have carcinoma in the contralateral breast, and two patients had intraductal carcinoma adjacent to the invasive papillary carcinoma. The varied mammographic features that may occur with this rare breast malignancy are discussed.     

Ultrasound spectrum in intraductal papillary neoplasms of breast

Intraductal papillary neoplasms (IPNs) of breast form a wide spectrum of pathological changes with benign intraductal papilloma occupying one end of the spectrum and papillary carcinoma at the other end. Intraductal papillomas are known to occur anywhere within the ductal system and are broadly classified into central and peripheral types. Intraductal papillary carcinoma is an uncommon ductal malignancy forming papillary structures, and these lesions characteristically lack the myoepithelial layer present in benign papillary neoplasms. Three basic patterns of IPNs are recognized on ultrasound - intraductal mass with or without ductal dilatation, intracystic mass and a predominantly solid pattern with the intraductal mass totally filling the duct. Benign papillomas are known to exhibit calcifications which tend to be extremely dense and coarse. IPNs are highly vascular tumours and have a propensity to bleed spontaneously. A distinct vascular pedicle is identified within the central core of IPNs, with branching vessels arborising within the mass. In an older age group, presence of a large solid component and evidence of spontaneous intracystic bleed are more suggestive of papillary carcinomas than benign papillomas. We have serially studied 42 cases of intraductal papillary neoplasms with sonomammography and mammography from 2001 to 2004.     

Underestimation of the presence of breast carcinoma in papillary lesions initially diagnosed at core-needle biopsy

PURPOSE: To retrospectively determine the degree of underestimation of breast carcinoma diagnosis in papillary lesions initially diagnosed at core-needle biopsy. MATERIALS AND METHODS: Institutional review board approval and waiver of informed consent were obtained for this HIPAA-compliant study. Mammographic database review (1994-2003) revealed core biopsy diagnoses of benign papilloma (n=38), atypical papilloma (n=15), sclerotic papilloma (n=6), and micropapilloma (n=4) in 57 women (mean age, 57 years). Excisional or mammographic follow-up (>or=2 years) findings were available. Patients with in situ or invasive cancer in the same breast or patients without follow-up were excluded. Findings were collected from mammography, ultrasonography, core technique, core biopsy, excision, and subsequent mammography. Reference standard was excisional findings or follow-up mammogram with no change at 2 years. Associations were examined with regression methods. RESULTS: In 38 of 63 lesions, surgical excision was performed; in 25 additional lesions (considered benign), follow-up mammography (24-month minimum) was performed, with no interval change. In 15 lesions, 14-gauge core needle was used; in 48, vacuum assistance (mean cores per lesion, 8.7). Carcinoma was found at excision in 14 of 38 lesions. Core pathologic findings associated with malignancy were benign papilloma (n=1), sclerotic papilloma (n=1), micropapilloma (n=2), and atypical papilloma (n=10). Frequency of malignancy was one (3%) of 38 benign papillomas, 10 (67%) of 15 atypical papillomas, two (50%) of four micropapillomas, and one (17%) of six sclerotic papillomas. Excisional findings included lobular carcinoma in situ (n=2), ductal carcinoma in situ (n=7), papillary carcinoma (n=2), and invasive ductal carcinoma (n=3). Low-risk group (micropapillomas and sclerotic and benign papillomas) was compared with high-risk atypical papilloma group. Core findings were associated with malignancy at excision for atypical papilloma (P=.006). Lesion location, mammographic finding, core number, or needle type were not associated (P>.05) with underestimation of malignancy at excision. CONCLUSION: Benign papilloma diagnosed at core biopsy is infrequently (3%) associated with malignancy; mammographic follow-up is reasonable. Because of the high association with malignancy (67%), diagnosis of atypical papilloma at core biopsy should prompt excision for definitive diagnosis.     

Radiology-Pathology conference: papillary carcinoma of the breast

Papillary carcinoma of the breast is a rare breast carcinoma. It can be classified into invasive and noninvasive types. It can also be classified into intracystic and intraductal papillary carcinoma. Different radiological features are found to be associated with different histological types. Pitfalls are found to be associated with fine needle aspiration and core biopsy in the evaluation of papillary lesions. It is therefore important for radiologists to diagnose papillary carcinoma for proper management of the patients.     

Unusual malignant tumors of the breast: MRI features and pathologic correlation

Unusual malignant breast tumors are well-differentiated subtypes of invasive ductal carcinoma, including mucinous, tubular, medullary and papillary carcinomas, and account for about 10% of malignant breast tumors. They are increasingly being encountered during magnetic resonance imaging (MRI) examinations of the breast. Therefore, breast radiologists should be aware of their appearance on MRI.This review provides an overview of MRI characteristics of a range of unusual tumors (mucinous carcinoma, medullary carcinoma, tubular carcinoma, intraductal papillary carcinoma, intracystic papillary carcinoma and invasive papillary carcinoma), highlighting specific clues for diagnosis and correlating MRI and pathologic features. Many unusual breast tumors exhibit MRI features similar to those of benign or low suspicious lesions (oval shape, well-defined margins, high signal intensity on T2-weighted images, continuous increase kinetics, i.e. type I dynamic curve), leading to a possible misdiagnosis. Nevertheless, an understanding of pathologic features of these tumors, especially tissue content (mucinous, fibrous) and growth pattern, can help to define some specific clues for their diagnosis.     

Imaging-guided core needle biopsy of papillary lesions of the breast

OBJECTIVE: Our objective was to assess the incidence of papillary lesions of the breast diagnosed at imaging-guided core needle biopsy and the need for surgical excision after a benign diagnosis. MATERIALS AND METHODS: This retrospective study included 1374 patients with consecutive suspicious breast lesions that underwent either mammography or sonographically guided large-core needle breast biopsy. Fifty-seven lesions (4%) were classified as papillary lesions. Eleven of the 57 cases were lost to follow-up (n = 6) or had not yet shown 2 years of stability (n = 5) and were excluded from this study. The remaining 46 papillary lesions constitute our study population. RESULTS: Surgical excision was performed in 17 (37%) of 46 papillary lesions. In the group of patients whose lesions were recommended for excision because carcinoma was identified at core biopsy, surgical excision revealed one false-positive and two true-positive diagnoses. In four cases, histologic diagnoses of the excisional biopsy and the core needle biopsy were discordant. One false-positive finding at core needle biopsy initially was interpreted as invasive ductal carcinoma on the basis of core needle biopsy specimens. In three false-negative findings, the initial diagnosis at core needle biopsy was upgraded after surgical excision. Two cases of papilloma with adjacent atypical ductal hyperplasia and one of atypical papilloma were upgraded to ductal carcinoma in situ after surgical excision. Imaging follow-up was performed in the remaining 29 patients. All lesions were stable or had decreased in size during the 2-year follow-up period. The negative predictive value of core needle biopsy for excluding malignancy among the papillary lesions diagnosed in our study was 93%. CONCLUSION: When the histologic diagnosis is benign, our data suggest that papillary lesions may be safely managed with imaging follow-up rather than with surgical excision. However, atypical papillary lesions or those associated with atypia require surgical excision because histologic underestimation occurs at a frequency similar to that in other atypical lesions undergoing core needle biopsy.     

Papillary lesions of the breast: evaluation with stereotactic directional vacuum-assisted biopsy.

PURPOSE: To evaluate the use of stereotactic directional vacuum-assisted biopsy (SDVAB) in diagnosing and managing papillary lesions of the breast. MATERIALS AND METHODS: The authors retrospectively reviewed the mammographic and histopathologic findings of 26 cases in which papillary lesions were diagnosed at SDVAB. In all cases, subsequent surgical excision (n = 20) or long-term imaging follow-up (n = 6) was performed and correlated with findings at SDVAB. RESULTS: SDVAB of 26 lesions yielded tissue that was classified as benign in 12, atypical in six, and malignant in eight. Of the 12 lesions that were diagnosed as histologically benign at SDVAB, six were surgically excised. Of these six lesions, five yielded benign correlative results. The sixth lesion was thought to be discordant with the imaging findings, and was surgically excised and determined to be malignant. Of the six benign lesions that were not surgically sampled for biopsy, five decreased in size and one was not seen at radiographic follow-up. Of the six lesions diagnosed as atypical at SDVAB that were surgically excised, one was benign and five were atypical. None proved to be malignant. Of the eight lesions diagnosed as malignant at SDVAB, surgical excision demonstrated ductal carcinoma in situ in all eight; two also had foci of invasive carcinoma. CONCLUSION: Benign and malignant papillary lesions of the breast can be reliably diagnosed at SDVAB when the SDVAB results correlate with the imaging findings. However, the extent of malignant papillary disease may be underestimated at SDVAB; in our study, invasive carcinoma was later discovered in 25% of patients with this diagnosis.     

Additional role of colour Doppler ultrasound imaging in intracystic breast tumours

Purpose

Cystic breast lesions with a nonsimple appearance, either complicated or complex, pose unique diagnostic difficulties, in part owing to their potentially malignant nature. Current ultrasound classification systems are based on morphostructural aspects only. The objective of this paper is to highlight the adjunctive role of Doppler techniques.

Materials and methods

Over a 1-year period, we prospectively evaluated 45 women with atypical breast cysts of type IV, V or VI according to the Chang classification. Forty patients were symptomatic, whereas the cyst was discovered as an incidental finding in five cases. Our assessment included morphostructural, angioarchitectural and flowmetric aspects.

Results

Twenty-three nontumoural lesions were managed conservatively. All 19 type-IV cysts and all four type-V cysts according to the Chang classification showed absence of signal flow at colour Doppler imaging. Among the 22 tumoural lesions, there were eight papillomas, one atypical ductal hyperplasia and 13 carcinomas. The eight papillomas showed single (four cases) or multiple (four cases) mural projections. The atypical ductal hyperplasia showed a single parietal nodule. Among the 13 carcinomas, patterns included mural projections in 11 cases, eccentric cystic wall thickening in one and coarse intracystic septa in one. Cystic content appeared clear in six papillomas and in the case of atypical ductal hyperplasia, whereas it exhibited fine echoes in two papillomas. Among the carcinomas, cystic content showed coarse echoes in two cases and fine echoes in 11. Intralesional calcifications were seen in three carcinomas. Posterior enhancement was present in all carcinomas, whereas none showed posterior shadowing. In three carcinomas, some small solid satellite nodules were evident. Colour Doppler imaging showed lack of flow in four papillomas and subtle flow in the remaining four papillomas and in the atypical ductal hyperplasia. All 13 carcinomas showed diffuse vascularity, with multiple sparse vessels and multiple vascular poles. The resistive index, measurable in 4/8 papillomas, was 0.43 on average. Spectral analysis was measured in all carcinoma cases, yielding a mean resistive index of 0.71.

Conclusions

Intracystic breast tumours exhibit distinctive morphostructural and colour Doppler features that allow effective differentiation from nontumoural cysts. Frequently, a presumptive differentiation between papillomas and carcinomas can be achieved. Absence of flow signals represents an additional criterion for complicated/complex cysts, allowing conservative management. Vascularity indicates the need for excision or biopsy of the solid projections, even in cases with negative cytology.     

Bilateral invasive papillary carcinoma of the breast

Papillary carcinoma, a rare malignant tumor of the breast, accounts for only 1–2% of breast tumors. It predominantly affects elderly women in the sixth decade to the eighth decade of life. The incidence of bilateral papillary carcinomas is very low, with only one case reported in the literature. However, there has been no report of a case of bilateral invasive papillary carcinoma. A case of bilateral invasive papillary carcinoma of the breasts, along with mammography and ultrasound findings, is reported here.     

Management of non malignant papillary lesions diagnosed on percutaneous biopsy

PURPOSE: To assess the reliability of percutaneous breast biopsies in diagnosing and managing non malignant papillary lesions and determine if subsequent excision must be systematic. MATERIALS AND METHODS. Retrospective review of 2233 breast biopsies over a 43 months period (September 2001 to March 2005): sonographically guided core biopsies (n = 836), ultrasound (n = 346) or stereotactic (n:1051) guided vacuum biopsies. 86 non malignant papillary tumors were diagnosed (core biopsy:28, US:38 and stereotactic guided vacuum biopsy:20). A larger sample was systematic after core biopsy: lumpectomy (n = 19) or vacuum biopsy (n = 9). Surgical excision followed vacuum biopsy (n = 18) in case of atypia or sampling excision. Alternatively, yearly follow-up was advised (n = 40). Correlation with surgical findings (n = 37) or mammographic follow-up (n = 49) is presented. The influence of various factors on the risk of underestimation was analysed. RESULTS: Surgical resection revealed an underestimation of 5/37 (13.5%): 4/19 with core- and 1/18 with vacuum-assisted biopsy corresponding to 4 low grade ductal carcinoma in situ and a microinvasive ductal carcinoma in situ. It was higher for core biopsies and related to age and size: higher when women<50 years and when radiological image>1 cm. The influence of the other factors was not significant. Of the 9 non operated papillomas after core biopsy, vacuum biopsy revealed an additional underestimation (low-grade ductal carcinoma in situ). Of the 49 papillary lesions that were not surgically biopsied, 40 were monitored at 2-42 months (average: 19 months). No carcinoma was detected during this follow-up. CONCLUSION: Percutaneous biopsy is an accurate technique in managing papillary tumors. A larger histologic specimen is necessary after core biopsy. Vacuum biopsy is an attractive alternative to surgery for smaller papillomas (<1 cm), but in spite of nonsignificant results we advise subsequent excision in case of multiple papillomas, atypia or residual tumor.     

Solid papillary breast carcinoma with mucinous differentiation

A case is reported of a solid variant of infiltrating papillary carcinoma of the breast with mucinous differentiation in a 74-year-old woman. Macroscopically, the tumor was solid and lobular, 4.5 cm in diameter. Light microscopy showed solid papillary invasive carcinoma mixed with infiltrating ductal carcinoma, not otherwise specified. Abundant intracellular and extracellular acid mucin produced by the solid papillary tumor cells was proven histochemically by: PAS, PAS-D, mucicarmine and alcian blue. Immunohistochemically, the papillary carcinoma cells were strongly reactive to estrogen receptors, and weakly to moderately reactive to smooth muscle actin. We suggest that papillary carcinoma of the breast could have potentially high degree of aggressiveness, and that differential diagnosis of these rare tumors might be a histopathological problem.     

Detecting the sentinel lymph node in patients with differentiated thyroid carcinoma

The aim of this study was to evaluate sentinel lymph node mapping in patients with differentiated thyroid carcinoma. Nine patients with suspected thyroid carcinoma who were scheduled to undergo thyroidectomy underwent scintigraphic localization of sentinel lymph nodes (SLNs). On the day of surgery we injected 37 MBq technetium-99m nanocolloid intratumourally. Dynamic data up to 10 min followed by planar anterior and lateral oblique images up to 1 h after tracer administration were recorded. At surgery the primary tumour was excised first, then the SLNs were removed using a gamma probe. Four patients had papillary carcinoma, two follicular carcinoma, one an oncocytic tumour and two benign tumours. An SLN was identified in all four patients with papillary carcinoma. In the two patients with follicular carcinoma, SLN detection failed. Five patients had one radioactive node, one had three and one had four. In one patient, no SLN was visible with scintigraphic imaging but at surgery three SLNs could be clearly identified using the gamma probe after removal of the primary tumour. There were no false-negative findings. This initial study indicates that in patients with papillary thyroid carcinoma detection of the SLN is possible, whereas the technique failed in two patients with follicular carcinoma. A study on a larger patient sample is now warranted.     

MR imaging screening of the contralateral breast in patients with newly diagnosed breast cancer: preliminary results

PURPOSE: To investigate the role of screening magnetic resonance (MR) imaging in the detection of synchronous contralateral breast cancer in patients with newly diagnosed breast cancer. MATERIALS AND METHODS: Between January 1999 and July 2001, 182 patients with newly diagnosed breast cancer (after either core or excisional biopsy with positive or close margins of resection) underwent bilateral contrast material-enhanced MR imaging at 1.5 T with a dedicated bilateral breast multicoil array. The contralateral breast was imaged for cancer screening. Family history of breast cancer, index cancer histology, breast density, and age at diagnosis of first breast cancer were assessed as potential risk factors for synchronous contralateral breast cancer. RESULTS: Fifteen patients (8.2%) had a suspicious enhancing lesion depicted in the contralateral breast. Seven patients (3.8%) had malignant results: ductal carcinoma in situ (DCIS) in four, invasive ductal carcinoma with DCIS in two, and invasive ductal carcinoma in one. Eight patients (4.4%) had benign results: fibrocystic changes in four, atypical ductal hyperplasia in two, atypical lobular hyperplasia and focal lobular carcinoma in situ in one, and ductal hyperplasia in one. Six patients with negative MR findings underwent prophylactic mastectomy; no malignancy was found. No significant differences were noted among patients with true-positive (n = 7), false-positive (n = 8), or negative (n = 167) MR findings with regard to family history of breast cancer (P <.27), index cancer histology (P <.19), breast density (P <.34), or age at diagnosis of first breast cancer (P <.10). CONCLUSION: The preliminary results demonstrate the feasibility of using MR imaging of the breast in a screening role, specifically to evaluate the contralateral breast in patients with newly diagnosed breast cancer to detect mammographically and clinically occult synchronous breast cancer.     

Papilloma and carcinoma of the choroid plexus in pediatric patients

Papillomas of the choroid plexus are rare tumors of neuroectodermal origin; they represent less than 5% of all central nervous system (CNS) tumors in pediatric patients. Choroid plexus carcinomas are even rarer. We reviewed the incidence of these neoplasms at our reference hospital and found six tumors of the choroid plexus (five papillomas and one carcinoma) in five patients. Patient age ranged from prenatal to 25 months. All five patients underwent computed tomography (CT) examination. Four perinatal patients underwent ultrasound examination, four magnetic resonance imaging (MRI), and one (years ago) angiography. All patients had tumors located in the lateral ventricles, and one patient had a second tumor located in the third ventricle. These tumors are predominantly solid, intraventricular, with well-defined polylobulated margins. They show intense vascularization on Doppler studies and marked contrast enhancement on CT and MRI studies. Hydrocephalus was present in three cases. All patients underwent surgery; total resection was achieved in the five papillomas, whereas the carcinoma was partially resected and the patient is currently undergoing chemotherapy. The three patients with a single papilloma are disease free at follow-up (range 7 months to 11 years). The patient with two papillomas shows good recovery at follow-up, whereas the patient with carcinoma of the choroid plexus has a poor prognosis.     

Sonographic features of primary breast cancer in men

OBJECTIVE: The imaging studies of eight men with proven primary breast cancer and preoperative sonography and mammography were reviewed and correlated with final pathology reports. CONCLUSION: There were five cases of invasive breast carcinoma and three cases of ductal carcinoma in situ of the papillary subtype. All three cases of papillary ductal carcinoma in situ showed cystic features on sonography. Most (4/5) invasive cancers were solid on sonography. The appearance of a complex cystic mass in the male breast on sonography should suggest the possibility of malignancy and therefore warrants biopsy.     

Proliferative pathology of the mammary ducts. Diagnostic value of ductogalactography and cytologic correlations

Three hundred and thirty-six patients with nipple discharge and neither physical signs at breast examination nor pathological findings at mammography, were observed from 1984 to 1988 and studied by means of ductogalactography and cytology of discharge. Of this group, 76 patients (22.6%) underwent surgery and histology. In 65/76 cases proliferative pathologic conditions were demonstrated: 51 single/multiple papillomas and 14 carcinomas. Ductogalactography suggested proliferative pathologic conditions in 59 cases and cytology of discharge showed blood in 44 patients, papillary clusters in 23, and atypical cells in 15 (both as single occurrences and in association). In cancer patients discharge appeared to be mostly spontaneous, monoductal and blood-stained. In papillomas, induced discharge was almost as frequent as spontaneous discharge, serous discharge was almost as frequent as blood-stained discharge, and milky discharge was also present. Ductogalactography confirmed its value in the diagnosis of proliferative pathologic conditions of the mammary ducts, being especially useful to detect carcinomas without palpable tumors. Cytology of discharge had poorer diagnostic significance.     

Sonographically-Guided 14-Gauge Core Needle Biopsy for Papillary Lesions of the Breast

Objective

We wanted to assess the need for surgical excising papillary lesions of the breast that were diagnosed upon sonographically guided 14-gauge core needle biopsy.

Materials and Methods

Sixty-nine women (age range: 25-74 years, mean age: 51.7 years) with 69 papillary lesions (4.9%) were diagnosed and followed after performing sonographically guided 14-gauge core needle biopsies. Surgical excision was performed for 44 (64%) of 69 papillary lesions, and 25 lesions were followed with imaging studies (range: 6-46 months, mean: 17.9 months). The histologic findings upon core biopsy were compared with the surgical, imaging and follow-up findings.

Results

Core needle biopsies of 69 lesions yielded tissue that was classified as benign for 43 lesions, atypical for 18 lesions and malignant for eight lesions. Of the 43 lesions that yielded benign papilloma upon core needle biopsy, one had intraductal papillary carcinoma found upon surgery. An immediate surgical biopsy was recommended for this lesion because of the imaging-histologic discordance. No additional carcinoma was found during the imaging follow-up. Surgical excision was performed for 17 atypical papillary lesions, and this revealed intraductal (n = 6) or invasive (n = 2) papillary carcinoma in 8 (47%) lesions. Of the seven intraductal papillary carcinomas, surgery revealed invasive papillary carcinoma in one (14%).

Conclusion

Our results suggest that papillary lesions of the breast that are diagnosed as benign upon sonographically guided 14-gauge core needle biopsy can be followed when the results are concordant with the imaging findings.     

Rare breast neoplasms: is there any peculiar feature on magnetic resonance mammography?

PURPOSE: The purpose of this study is to describe the semiological features of rare breast neoplasms at magnetic resonance mammography (MRM). MATERIALS AND METHODS: Out of 468 MRMs of patients with a histological diagnosis of breast malignancy, 27 (5.7%) cases of rare breast neoplasms, confirmed by definitive histological analysis on surgical specimens, were selected: four (0.9%) intracystic papillary neoplasms, four (0.9%) intraductal papillary neoplasms, five (1.0%) invasive papillary neoplasms, two (0.4%) medullary carcinomas, seven (1.5%) mucinous carcinomas, three (0.6%) tubular carcinomas, one (0.2%) tubulo-lobular carcinoma and one (0.2%) desmoid tumour. Two radiologists evaluated the MRM images according to Fischer criteria and indicated a level of diagnostic suspicion. In particular, MRM lesion morphology and enhancement characteristics were analysed. RESULTS: No semiologic features of malignancy or peculiar appearances indicating rare breast neoplasm were identified. On the contrary, MRM appearance was nonspecific and often suggestive of probably benign (Breast Imaging Reporting and Data System-BI-RADS 3) (40%) or benign lesions (BI-RADS 2) (7.5%), or lesions were undetectable at MRM (BI-RADS 1) (7.5%). CONCLUSIONS: Frequently, rare breast neoplasms show low suspicious morphologic and kinetic patterns at MRM, and they are often classified as indeterminate lesions. This is probably due to their high grade of differentiation and their histological features.