Case Presentation - Spring, 2011

Patient History: 53 year old female with a history of breast cancer diagnosed as infiltrating ductal carcinoma with squamous differentiation and extensive necrosis, grade 2, with axillary metastases. Liver metastases developed. The patient subsequently received chemotherapy. One year later, the patient presented with new enlarging liver lesions.

Specimen type: Liver FNA

Cytology and biopsy diagnosis: Metastatic adenosquamous cell carcinoma of the breast

Immunohistochemistry: Positive for E-cadherin and mammoglobin. Negative for TTF-1, progesterone receptor and Her2/neu.

Case provided by: Milstead Pathology, Conyers, GA

Adenosquamous carcinoma of the breast is part of a family of tumors known as metaplastic carcinoma, which is comprised of three types: adenosquamous carcinoma, carcinosarcoma and sarcomatoid carcinoma. Adenosquamous carcinoma typically occurs at an average age of 54 years old and is a very rare disease, comprising only 0.2% of breast malignancies. The tumor presents as a palpable mass at any site in the breast. In addition to new masses, a patient may experience nipple tenderness and/or discharge. Skin irritations including puckers, dimples, scaliness or new creases can occur along with warm, red, swollen breasts with a rash resembling the skin of an orange (peau d'orange).

Cytology and Histology:
FNA biopsy specimens are highly cellular and reveal a biphasic pattern of malignant glandular cells (of ductal origin) and malignant squamous cells with the glandular portion usually predominating; occasionally, the squamous component does predominate. Pleomorphism, multinucleation and mitoses can be seen. This tumor has the ability to change to a spindle cell carcinoma so the differential diagnoses include stromal sarcoma, spindle cell proliferations, angiosarcoma, phyllodes tumor and metastatic carcinomas. Immunohistochemistry can be used to verify epithelial origin. Positive results are seen with vimentin, cytokeratin and S-100. Electron microscopy enables the identification of well-developed desmosomes and tonofilaments that also confirm the epithelial origin of the tumor.

Because adenosquamous carcinoma is rare, specific optimal treatment options are unknown. Therefore, patients receive the same treatment as those diagnosed with ductal carcinoma or lobular carcinoma. It has an unfavorable prognosis with a survival rate of 44% at five years. The tumor is surgically removed by performing a lumpectomy or a mastectomy, with lymph node biopsy and removal if necessary, followed by adjuvant therapies including radiation therapy, chemotherapy and/or targeted therapy (targeting faulty genes or proteins). The combination of therapies and drugs administered varies from patient to patient and is dependent upon tumor size, location, grade, the patient's overall general health, menopausal status and results of BRCA1 or BRCA2 testing. Participation in clinical trials may also be considered. Additionally, research using different drug therapies, surgical techniques and improved radiation therapy is currently being conducted.

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