Case Report

Metastasis of Primitive NeuroectodermalTumor to the Breast

Jin-Young Kwak, MD,1 Eun-Kyung Kim, MD,1 Jai Kyung You, MD,1 Ki Keun Oh, MD,1

Soon Won Hong, MD,2 Se Hoon Kim, MD2

1 Department of Diagnostic Radiology, Research Institute of Radiological Science, Yonsei University College ofMedicine, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752, Korea2 Department of Pathology, Research Institute of Radiological Science, Yonsei University College of Medicine,134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752, Korea

Received 24 September 2001; accepted 22 January 2002

ABSTRACT: We performed mammography and so-nography on a 49-year-old woman who had a mass inher left axilla that had been present for 1 month andwho had undergone excision of a primitive neuroec-todermal tumor (PNET) on her back 1 year before.Mammography revealed 2 adjacent, dense nodules inthe left breast and enlarged lymph nodes, without afatty hilum or internal microcalcifications, in the leftaxilla. Sonography showed 2 round to oval, markedlyhypoechoic nodules in the left breast and enlarged,markedly hypoechoic lymph nodes, without micro-calcifications, in the left axilla. We then performedsonographically guided core biopsy. Histopathologicanalysis of the specimens confirmed the presenceof PNET in the left breast and axillary lymph nodes.The patient was then treated with chemotherapy. Toour knowledge, this report is the first to describeradiologic findings of metastasis of PNET to thebreast. © 2002 Wiley Periodicals, Inc. J Clin Ultra-sound 30:374–377, 2002; Published online in Wiley In-terScience (www.interscience.wiley.com). DOI:10.1002/jcu.10076

Keywords: breast neoplasm; breast metastasis; breastultrasonography; primitive neuroectodermal tumor;ultrasound-guided core biopsy

Metastases in the breast that originate fromprimary tumors in other sites are relatively

rare. The reported incidences of nonprimary ma-lignancies in the breast ranged from 1.7% to 6.6%in an autopsy series1 and from 0.5% to 1.3% in aclinical setting.2 Because metastases of nonbreastprimary tumors to the breast are so rare, histo-pathologic and clinical characteristics usually of-

fer little help in diagnosing these metastases ra-diologically.

Primitive neuroectodermal tumor (PNET) is asmall round cell malignancy that arises in softtissue or bone. The primary sites of involvementare the chest wall, trunk, retroperitoneum, pelvis,and extremities.3 We report the case of a patientwith metastasis of PNET to the breast and axil-lary lymph nodes who underwent mammography,sonography, and sonographically guided core bi-opsy. To our knowledge, this report is the first todescribe radiologic findings of PNET metastasisin the breast.

CASE REPORT

A 49-year-old woman was referred to us for evalu-ation of a mass in her left axilla that she had hadfor 1 month. A year before we examined her, shehad undergone surgical excision of a PNET on herback. The referring physician was a surgeon who,on the basis of radiologic findings, suspected pri-mary breast cancer with metastasis to the axil-lary lymph nodes and who recommended sono-graphically guided core biopsy.

We first performed mammography using aSenographe DMR mammography unit (GE Medi-cal Systems, Milwaukee, WI) and then sonogra-phy using an HDI 3000 ultrasound scanner (Ad-vanced Technology Laboratories, Bothell, WA)equipped with a 10-MHz linear-array transducer.

Mammography showed 2 adjacent, high-density nodules in the lateral upper quadrant ofher left breast. The mediolateral oblique viewshowed enlargement of the lymph nodes in the

Correspondence to: E.-K. Kim

© 2002 Wiley Periodicals, Inc.

374 JOURNAL OF CLINICAL ULTRASOUND

ipsilateral axilla, without a fatty hilum (Figure1). An exaggerated craniocaudal view showed 2lobular nodules with microlobulated margins andno internal microcalcifications (Figure 2).

Sonography showed 2 round to oval, markedlyhypoechoic, well-circumscribed nodules at the 3o’clock position, 6 cm from the nipple (Figure 3)and enlarged, markedly hypoechoic axillarylymph nodes without microcalcifications.

We also performed the recommended sono-graphically guided core biopsy of the breast massand enlarged axillary lymph nodes. Histopatho-logic examination of the biopsy specimens re-vealed the presence of PNET in both the breastand the axillary lymph nodes (Figure 4).

Despite treatment with 2 courses of chemo-therapy with doxorubicin (Adriamycin) and cis-platin, the masses did not decrease in size. Thepatient chose not to undergo further treatmentand did not return for follow-up.

DISCUSSION

Metastases in the breast that arise from primarytumors in other sites are relatively rare. One re-

port has even suggested that among patients witha known primary tumor in the breast or othersite, the subsequent finding of another malig-nancy in the breast is more likely to be a newlydeveloped primary tumor of the breast than a me-tastasis of the original primary tumor.4 Primarymalignancies that have been found to metastasizeto the breast include melanoma, lymphoma, ovar-ian cancer, lung cancer, and, less commonly, blad-der cancer, renal cell cancer, choriocarcinoma,and gastric cancer. Malignancies can metastasizeto the breast through either the lymphatic systemor the circulatory system. The mammographicappearance of metastases in the breast is mostcommonly described as single or multiple circum-scribed masses of varied size that have well-defined or irregular margins and that are located

FIGURE 1. Mediolateral oblique mammograms show 2 high-densitylobular nodules, with slightly irregular margins, in the upper portionof the left breast.

FIGURE 2. Exaggerated craniocaudal mammogram shows 2 lobularnodules without internal microcalcifications and with partially indis-tinct margins.

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in the lateral upper outer quadrant of the breast,without spiculation, calcifications (except in casesof metastases that originate from papillary cancerof the ovary), or other signs of desmoplastic re-sponse that characterize many primary carcino-mas. The sonographic features of metastases inthe breast vary, but these metastases may appearas well-defined, circumscribed solid masses thatare hyperechoic or hypoechoic and with or with-out posterior shadowing.5,6

Compared with primary breast cancer, metas-tases to the breast can be more difficult to diag-nose histopathologically. In a previous report, his-topathologic examination of a breast biopsy

specimen revealed a metastasis in a periductal orperilobular distribution even though neither in-traductal carcinoma nor lobular carcinoma in situwas found.2 Differentiation between primarybreast carcinoma and metastasis to the breast isimportant because radical surgery is unnecessaryfor treatment of such metastases. Careful atten-tion is necessary in cases in which a breast lesionis the first manifestation of an unknown primarymalignancy, especially in young patients. Innearly 25% of cases of metastases to the breast,the metastases are the presenting manifestationof an otherwise occult malignancy elsewhere inthe body.2

Predisposing factors for metastasis to thebreast have not been identified. However, re-searchers have suggested that hormonal factorsplay a role in metastasis of rhabdomyosarcoma tothe breast in children.7 Metastasis to the breastsuggests advanced systemic disease.5 Indeed, theoverall prognosis of patients with metastasis tothe breast is extremely poor; more than 80% diewithin 1 year after diagnosis.2

PNET, a small round cell malignancy, is diag-nosed primarily in older children and adolescents; itoccurs very rarely in adults. PNET is locally aggres-sive but can metastasize. In 1 series that retrospec-tively reviewed the outcomes of 26 patients, PNETmetastasized to the lung (31%), bone (12%), bonemarrow (12%), and lymph nodes (31%).3 Althoughinvestigators have previously reported metastasisof PNET to various sites, our report is the first toidentify metastasis of PNET to the breast.

FIGURE 3. Sonogram of the left breast shows 2 markedly hypoechoic, round to oval nodules.

FIGURE 4. Photomicrograph of the core biopsy specimen from thebreast mass shows diffuse infiltration of small round cell tumor, find-ings consistent with metastatic primitive neuroectodermal tumor (he-matoxylin-eosin stain; original magnification, 200×).

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In this case, because metastasis of PNET to thebreast had never been reported, we initially sus-pected primary breast cancer with axillary lymphnode metastasis even though we knew the pa-tient’s history of PNET on her back. Furthermore,the mammographic and sonographic findingswere consistent with the appearance of primarybreast cancer with axillary node metastasis.Sonographically guided core biopsy of the breastconfirmed that the patient’s metastasis wasPNET, thus allowing her to avoid unnecessarysurgery. However, the histopathologic examina-tion showed that the core biopsy specimen fromthe breast mass included neither surroundingbreast tissue nor lymphoid tissue. Therefore, wecannot exclude the possibility that this specimendid not represent a metastasis to the breast butrather an intramammary lymph node that hadbeen completely replaced with metastatic tumorfrom PNET. We did not perform any additionaldiagnostic procedures because clarification of thespecimen’s origin would not have altered the pa-tient’s prognosis or our treatment recommenda-tions.

In summary, we report a rare case in whichmetastasis of PNET to the breast was initiallybelieved to be primary breast cancer on the basisof mammographic and sonographic findings.Sonographically guided core biopsy confirmed

that the tumor was PNET, allowing unnecessarysurgery to be avoided. In treating patients whohave a history of PNET, physicians should beaware that the radiographic features of PNETmetastases in the breast may be consistent withthose of primary breast malignancy.

REFERENCES

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2. Hajdu SI, Urban JA. Cancers metastatic to thebreast. Cancer 1972;29:1691.

3. Marina NM, Etcubanas E, Paham DM, et al. Pe-ripheral primitive neuroectodermal tumor (periph-eral neuroepithelioma) in children: a review of theSt. Jude experience and controversies in diagnosisand management. Cancer 1989;64:1952.

4. McIntosh IH, Hooper AA, Millis RR, et al. Meta-static carcinoma within the breast. Clin Oncol1976;2:393.

5. Vizcaı́no I, Torregrosa A, Higueras V, et al. Metas-tasis to the breast from extramammary malignan-cies: a report of four cases and a review of litera-ture. Eur Radiol 2001;11:1659.

6. Yang W, Metreweli C. Sonography of nonmam-mary malignancies of the breast. AJR Am J Roent-genol 1999;172:343.

7. Howarth CB, Caces JN, Pratt CB. Breast metasta-ses in children with rhabdomyosarcoma. Cancer1980;46:2520.

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