Human epidermal growth factor receptor 2-positive microinvasive breast carcinoma with a highly aggressive course: a case report

BACKGROUND: Microinvasive ductal carcinoma in situ of the breast is a rare entity defined as ductal carcinoma in situ with invasive foci measuring no more than 1 mm. In general, the outcome is excellent, similar to ductal carcinoma in situ. We report a patient with breast ductal carcinoma in situ with microinvasion who died eight months after diagnosis due to progression of the disease – liver metastases. This is the first report in the literature of such an aggressive course. CASE PRESENTATION: A 47-year-old Caucasian woman presented with mammographic-detected suspicious microcalcinations in an area of 8.6 x 6 cm. A radical mastectomy with a sentinel lymph node biopsy and immediate breast reconstruction with implant was performed. A histopathological report showed a massive high grade ductal carcinoma in situ, of the solid and comedo type. In one quadrant, some foci of microinvasions of less than 1 mm were present. Tumour margins were free. Isolated tumour cells were found in the sentinel lymph node. Hormone receptors were negative and human epidermal growth factor receptor-2 status was not performed. The patient received no adjuvant systemic therapy. Eight months after the surgery, she died from hepatic failure without known breast cancer progression before. An autopsy revealed diffuse liver metastases with human epidermal growth factor receptor 2-positive, hormone receptor negative breast cancer. Dissemination to other organs was not proven. CONCLUSION: Our patient is a rare case of ductal carcinoma in situ with microinvasion that developed distant metastases very early. In case of multiple foci of microinvasion, besides radical local treatment we suggest considering adjuvant systemic treatment based on biological characteristics since tumour size alone does not predict the prognosis well.