To demonstrate the mammographic and sonographic appearances of metaplastic carcinoma of the breast.

The mammographic and sonographic findings in eight female patients (aged: 28-78 years, mean: 50.3 years) with pathologically proven metaplastic cancer were analyzed retrospectively by three radiologists. We analyzed the size, density, shape, margin, associated architectural distortion, calcification in the mass and enlarged lymph node at the axilla, on the mammograms. We also analyzed the shape, margin and echogenicity of the lesions on the sonograms.

On mammography, irregular (n=4), lobular (n=2) or oval (n=2) shaped high density masses were found. The margins of the masses were indistinct (n=4) or obscured (n=3). There were architectural distortions in three cases and pleomorphic calcifications in two cases. On sonography, irregular (n=5) or oval (n=3) shaped masses with microlobulated margins were found. The echopatterns of the masses were complex (n=5) or hypoechoic (n=3).

The mammographic and sonographic findings of metaplastic carcinoma of the breast are nonspecific and similar to those of other forms of breast cancer. However, this type of tumor should be included in the differential diagnosis for breast masses which appear as an irregular or oval shape with a microlobulated margin and a complex or hypoechoic echopattern on sonography.