Abstract P1-12-03: Primary squamous cell carcinoma of the breast
Authors: Lee ES , Lundberg TM , Ley MB , Waer A , Livingston RB , Stopeck AT , Chalasani P , Gonzalez VJ , LeBeau LG , Rose JF , Viscusi RK 
Published: August 2014

Abstract
BACKGROUND: Primary squamous cell carcinoma of the breast (PSCCB) is one of the rarest forms of breast cancer, accounting for less than 0.1% of all breast cancers. PSCCB can be aggressive with no typical radiologic findings on mammogram, often leading to delays in diagnoses or missed diagnoses. Previously reported cases of PSCCB have illustrated a wide range of clinical presentations, from an abnormal mammogram with no obvious breast mass to a breast abscess. In addition, due to the rarity of this disease, no clear consensus on definitive treatment or prognosis exists.
METHODS: Using a search of our pathology database, we identified females diagnosed with PSCCB at our institution from 2007-2012. Inclusion criteria included female patients over the age of 18 years old with a primary tumor consisting of &gt;90% malignant cells of squamous origin. Likewise, exclusion criteria included squamous cell cancer that had metastasized to the breast from elsewhere or lesions that were not independent of the overlying skin or nipple. We then performed a retrospective review to evaluate patient characteristics, presentation, tumor characteristics, treatment modalities and outcomes.
RESULTS: We identified three patients who were diagnosed with PSCCB during that timeframe. Their ages ranged from 35-65 years old, with two being post-menopausal and one pre-menopausal. Of the three, two were Caucasian and one was Hispanic. All three presented after self-palpating a breast mass. The average size of the mass seen on mammogram was 2.9 cm (range of 2.4 to 3.6 cm). Histologically, all three of the cancers were moderately to poorly differentiated. In addition, they all had a negative estrogen, progesterone, and HER2 receptor status with an elevated Ki-67. One patient was diagnosed at our institution but did not proceed to surgery and was lost to follow up. For the other two patients, one chose to undergo breast conservation with partial mastectomy and sentinel lymph node biopsy followed by whole breast radiation. The second patient proceeded with a total mastectomy and sentinel lymph node biopsy without radiation. There was no evidence of regional nodal disease in either patient at time of surgery. Furthermore, neither patient received any systemic therapy. Both patients were disease free at last follow up which was 5 and 11 months respectively.
CONCLUSION: Because PSCCB is so rare, prognosis and optimal treatment are still controversial. Most of the current literature portrays PSCCB as an aggressive cancer with a poor prognosis. This often leads to multimodality therapy consisting of mastectomy with axillary nodal clearance, adjuvant chemotherapy and radiation. In addition, locoregional and distant recurrences are common despite this aggressive treatment leading to the conclusion that PSCCB is relatively radioresistant with limited activity seen when using conventional breast cancer systemic therapies. Because treatment options can be limited, more research is needed to further elucidate the biological behavior of this rare cancer as well prognostic factors that may allow us to treat a patient more conservatively.
Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-12-03.