Metaplastic breast carcinoma with osseous differentiation: a case report.

Abstract: Metaplastic breast carcinoma is a rare entity with the distinguishing feature of having epithelial and mesenchymal tissue types incorporated within one tumor. This is a case report of a patient found to have a rare metaplastic breast carcinoma with prominent osseous differentiation. Radiologic and pathologic correlation is provided.

Key Words: metaplastic breast carcinoma, osseous differentiation

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Metaplastic breast carcinoma is a rare entity with the distinguishing feature of having epithelial and mesenchymal tissue types incorporated within one tumor. This is a case of a patient found to have a metaplastic breast carcinoma with prominent osseous differentiation.

Case Report

This 53-year-old female presented to our institution for a routine annual screening mammogram. Routine screening mammograms 2 years prior were normal. The mammograms (Figs. 1 and 2) showed a new, well circumscribed, hyperdense, 1.5 cm round mass at the 3 o'clock position in the posterior third of the right breast. The borders of the mass appeared to be microlobulated. Within the mass there were multiple dense, thick, nonbranching linear areas of calcification. Ultrasound was performed (Fig. 3) and showed a 1.5 X 1.4 cm well circumscribed, ovoid mass with central hyperechoic regions with dense posterior shadowing. Though the lesion was relatively well circumscribed, its acute presentation and the unusual morphology of the calcifications raised the level of suspicion of malignancy and biopsy was recommended.

On clinical examination, a dominant mass was noted that correlated with the radiographic findings. The mass had well-defined margins without fixation to the skin or the chest wall. Fine needle aspiration was nondiagnostic; therefore, she underwent excisional biopsy. Pathologic examination showed a very well-circumscribed tumor 1.5 cm in diameter. The main tumor mass was reported as metaplastic carcinoma, with foci of solid and comedo ductal carcinoma in situ extending beyond the margins of the main tumor mass. In addition, there were areas of chondroid differentiation, osseous differentiation, and osteoclast-like giant cells. Squamous differentiation and spindle cell areas were not identified (Fig. 4). Immunohistochemistry stains were also performed (Table).

The patient was diagnosed with invasive metaplastic carcinoma, heterologous type and ductal carcinoma in situ and subsequently underwent modified radical mastectomy. Pathologic examination showed no residual carcinoma. Axillary lymph nodes were negative for metastatic carcinoma. At 18-month follow-up the patient showed no clinical or radiographic evidence of recurrence.

Discussion

Metaplastic carcinoma of the breast is rare, making up 0.2% of all breast cancers. (1) The clinical and radiographic presentation may vary depending on the tissue subtypes within the lesion. (2-3) Metaplastic carcinomas may have a dominant tissue subtype or contain mixed elements of squamous cell, spindle cell, chondroid, or osseous metaplasia. (1) Of the 81 metaplastic carcinomas reported, 21 were predominately chondroid, 18 were predominately squamous, 14 were predominately spindle cell, and 6 showed predominately osseous metaplasia. The remaining lesions were mixtures of the above components. (8-15) A review of the radiology literature shows that the osseous subtype of metaplastic carcinoma with macroscopic calcifications visible on mammography and ultrasound has not been previously described to our knowledge. (10-15) Previous descriptions of metaplastic carcinoma based on small case series have suggested that calcifications not be considered characteristic of the tumor. (13,15) However, based on this case and a prior case reported by Evans et al, in the rare cases of metaplasia with predominately osseous differentiation, macroscopic calcifications may be seen on mammography. (12) Microcalcifications have been reported in 7/49 or 14% of cases, and are seen with all subtypes of metaplasia. (10-15) While this case is unusual with regard to the prominent macroscopic calcifications, it does contain more typical radiographic features of metaplastic carcinomas. The size, shape, density, and margins of the mass in this case are consistent with the hyperdense, round to oval, well-circumscribed masses. The literature contains articles describing the various subtypes of metaplastic carcinoma and includes radiographic images, largely of those with squamous differentiation. However, few images demonstrate prominent osseous differentiation. The tumor described here is a well-circumscribed, round to oval mass with irregular borders, features commonly described in metaplastic carcinomas. (4) The 1.5 cm size of the lesion is below the average of 3.4 cm. (5) The typical ultrasound appearance is that of a hypoechoic, well-circumscribed lesion with a mixed echotexture, depending on the constituent tissue subtypes contained within the mass. (6) Previous sonographic findings of metaplastic carcinomas with predominate osseous metaplasia do not exist to our knowledge. In this case the unusually prominent osseous elements produce pronounced acoustical shadowing. This finding of dense shadowing appears to be unique to the osseous subtype of the carcinoma.

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Overall 5-year survival ranges between 33% and 86%. (7) The largest factor affecting survival is TNM stage with Stage I having a 56%, 5-year survival. Stage II has a 26%, 5-year survival, and Stage III has an 18% 5-year survival. Prognosis is based on tumor size, nodal status, grade, histologic type and degree of metaplasia. (1) A review of the literature shows the lymph nodes were positive in 18/68 or 26% of patients with local recurrence seen in 8/32 or 25% of patients. (8-15) No large series of these carcinomas exist secondary to their uncommon occurrence. Consequently, little empiric data exists regarding outcome and appropriate therapy. The current recommendation is for patients to be treated and followed similarly to patients with more common forms of breast cancer. (4)

Conclusions

Metaplastic breast carcinomas are rare, with a variety of tissue subtypes seen in one mass. They are usually well circumscribed on mammography; however, the appearance is highly dependent on the tissue subtypes included within the mass. Osseous differentiation in a metaplastic carcinoma is seen in approximately 7% of metaplastic carcinomas. The osseous subtype usually produces macroscopic calcifications visible on mammography and ultrasound while retaining the more characteristic features of the more common metaplastic carcinoma subtypes.

References

1. Kaufman MW, Marti JR, Gallager S, et al. Carcinoma of the breast with pseudosarcomatous metaplasia. Cancer 1984;53:1908-1917.

2. Smith DM, Rongaus VA, Wehmann TW, et al. Metaplastic breast carcinoma. J Am Osteopath Association 1996;96:419-421.

3. Johnson TL, Kini SR. Metaplastic breast carcinoma, a cytohistologic and clinical study of 10 cases. Diagnostic Cytopathology 1996;14:226-232.

4. Greenberg D, McIntyre H, Bierre T. Metaplastic Breast Cancer. Australasian Radiology 2004;48:243-247.

5. Rayson D, Adjei AA, Suman VJ, et al. Metaplastic breast cancer: prognosis and response to systemic therapy. Annals of Oncology 1999;10:413-419.

6. Park JM, Han BK, Moon WK, et al. Metaplastic carcinoma of the breast: mammographic and sonographic findings. Journal of Clinical Ultrasound 2000;28:179-186.

7. Elston CW, Ellis IO. Vol. 13. The Breast. In: Systemic Pathology. 3rd ed. Churchill Livingstone, Edinburgh, 1998, pp 323-328.

8. Oberman HA. Metaplastic carcinoma of the breast. A clinicopathologic study of 29 patients. Am J Surg Pathol 1987;11:918-929.

9. Chhieng C, Cranor M, Lesser ME, et al. Metaplastic carcinoma of the breast with osteocartilaginous heterologous elements. Am J Surg Pathol 1998;22:188-194.

10. Park JM, Han BK, Moon WK, et al. Metaplastic carcinoma of the breast: mammographic and sonographic findings. J Clin Ultrasound 2000;28:179-186.

11. Brenner RJ, Turner RR, Schiller V, et al. Metaplastic carcinoma of the breast: report of three cases. Cancer 1998;82:1082-1087.

12. Evans HA, Shaughnessy EA, Nikiforov YE. Infiltrating ductal carcinoma of the breast with osseous metaplasia: imaging findings with pathologic correlation. AJR 1999;172:1420-1422.

13. Patterson SK, Tworek JA, Roubidoux MA, et al. Metaplastic carcinoma of the breast: mammographic appearance with pathologic correlation. AJR 1997;169:709-712.

14. Velasco M, Santamaria G, Ganau S, et al. MRI of metaplastic carcinoma of the breast. AJR 2005;184:1274-1278.

15. Gunhan-Bilgen I, Memis A, Ustun EE, et al. Metaplastic carcinoma of the breast: clinical, mammographic, and sonographic findings with histopathologic correlation. AJR 2002;178:1421-1425.</p> <pre> Once you label me you negate me. --Soren Kierkegaard </pre> <p>Jeffrey M. Pollock, MD, Allan Green, MD, Cynthia Donnell, MD, Donna Lynn Dyess, MD, and J. Allan Tucker, MD

From the University of South Alabama, Mobile, AL.

Reprint requests to Jeffrey M. Pollock, MD, University of South Alabama, 2451 Fillingham Street, Mobile, AL 36617. Email: [e-mail]

Accepted August 17, 2005.

RELATED ARTICLE: Key Points

* Metaplastic breast carcinoma is a rare form of breast cancer with a variety of presentations dependent on the tissue subtypes incorporated within the lesion.

Table. Immunohistochemistry stains

Estrogen Receptors                 Negative
Progesterone Receptors             Negative
Her-2/neu                          Negative (score 1+)
S-100                              Positive in mesenchymal and
                                     epithelial components
Low Molecular Weight Cytokeratin   Positive diffusely in the epithelial
                                     component
High Molecular Weight Cytokeratin  Negative
CD-68                              Positive in the osteoclast-like giant
                                     cells.