Breast carcinosarcoma

Clinical History

A 63-year-old female patient was referred to our breast unit due to a palpable mass in the left breast having developed for one month.
Her previous mammography was done in a screening centre, outside our hospital.

Imaging Findings

Mammography showed an almost entirely fatty breast (A type). On the upper external quadrant of the left breast, there was an oval, lobulated and high density nodule. There were no calcifications, architectural distortions or asymmetries. Skin and axillae were normal (Figs. 1-2).
Ultrasound showed, on the upper external quadrant of the left breast and coinciding with the mammography lesion, a solid nodule, irregular, with indistinct margins, hypoechoic, with hyperechogenic edge and without posterior features (BI-RADS 4C). Elastography was not performed. Axillae were normal (Fig. 3).
We performed a core needle biopsy guided by ultrasound. Histological exam showed an undifferentiated solid neoplasm with high nuclear atypia and high mitotic rate with 70% of sarcomatoid pattern (negative with cytokeratins and positive with vimentin) and 30% of solid epithelioid areas that show positivity with epithelial markers (cytokeratin AE1 / AE3)(Fig. 4).

Discussion

A. Background
Breast carcinosarcomas are a subtype of metaplastic carcinoma and are the rarest primary tumours of the breast (<0, 1%) [1]. Metaplastic carcinomas can be classified as a purely epithelial type (squamous, adenocarcinoma with spindle cell differentiation, adenosquamous) and mixed epithelial and mesenchymal type (carcinoma with chondroid metaplasia, with osseous metaplasia and carcinosarcoma, as our type) [2].

B. Clinical Perspective
Carcinosarcomas usually present as a symptomatic palpable and fast-growing mass in women who are more than 50 years old [1, 3]. It is important to differentiate carcinosarcomas with a high sarcomatoid component (as in our case) from primary breast sarcomas, because the treatment and spread dissemination are different [1, 3]. In breast sarcomas, lymph node metastases are infrequent and in metaplastic carcinomas, although they are infrequent [3, 4], they can be seen in 25-40% of cases [1, 5]. The most common metastases are in the lungs [4].

C. Imaging Perspective
Although imaging appearance is nonspecific, carcinosarcoma usually presents in mammography as a high density mass without microcalcifications and predominantly circumscribed margins [1, 3, 5, 6]. On ultrasound, they are usually masses with solid and cystic components due to necrosis and cyst degeneration [1, 5], or oval or lobular solid masses with circumscribed or indistinct margins [6].
On MRI, they show an isointense or hypointense signal in T1-WI and an increase of signal in T2-WI, related to the necrotic component that obligates to do a differential diagnosis among mucinous carcinoma and necrotic infiltrating ductal carcinoma [5].
Due these unspecific features, the core biopsy is necessary.

D. Outcome
Although some authors suggest that the treatment is similar to other ductal carcinomas [5, 7], others prefer surgical treatment with modified radical mastectomy and chemotherapy [4].
In our patient, due to the biopsy result and their limited localization, the breast unit committee decided to perform a surgical resection with previous localization of the lesion by an ultrasound-guided harpoon (Figs. 5-6).
Because of their possible lymph node spread, axillary examination with sentinel node biopsy and/or axillary dissection should be done [7]. In our case, sentinel lymph node biopsy and body CT scan were negative.
The overall 5-year survival rate is 40-49% [1, 7].

E. Take Home Message
A breast lesion with rapid growth could suggest a breast carcinosarcoma.

Differential Diagnosis List

Final Diagnosis

Breast carcinosarcoma

URL:	https://www.eurorad.org/case/14385
DOI:	10.1594/EURORAD/CASE.14385
ISSN:	1563-4086