Parotid Gland Metastasis from Breast Origin

Introduction: Metastatic involvement of parotid gland from breast carcinoma is rare. According to a literature review, only 24 cases have been reported. Case report: A 48-year-old woman with a history of left breast cancer complained of swelling in the right parotid gland. Biopsy was performed and made the diagnosis of metastasis from breast carcinoma. The patient was treated by chemotherapy and radiotherapy. Conclusion: Local control of the disease should not be underestimated and a multimodal treatment combining surgery, radiotherapy and chemotherapy should be given every time it seems possible.


Introduction
Parotid tumors represent 3% of head and neck tumors and 80% of salivary gland tumors [1]. The parotid metastasis from breast carcinoma is extremely rare. To our knowledge 24 cases are published nowadays. There is no therapeutic consensus. The management depends on the stage of the disease and the prognosis is dark. We report a case of parotid gland metastasis of breast cancer with review of the literature.

Case Report
A 48-year-old woman, presented in 2005 a left breast carcinoma classified T2N2aM0 according to TNM classification. She had a mastectomy associated with axillary lymph node dissection. Histological examination revealed an invasive ductal carcinoma (IDC) of 2.5 cm, grade II according to Scraff-Bloom-Richardson score (SBR), hormonal receptors positive; 2 lymph nodes out 7 identified were invaded (2N ± 7N). She underwent eight cycles of adjuvant chemotherapy with 5-Fluotouracil -Epiribucin -cyclophosphamid (FEC) and paclitaxel followed by locoregional radiotherapy at the dose of 52.2 Gy completed in August 2008. A hormone therapy with tamoxifen was prescribed for five years. In 2013 she presented a pulmonary metastatic relapse treated with five courses of FEC followed by aromasine. One year later, she developed cutaneous metastases treated with tamoxifen. In 2015, she had letrozole for bone progression. In July 2016, physical examination identified a firm right parotid mass measuring 5 cm, not painful and without signs of facial nerve involvement. The biopsy revealed an invasive ductal carcinoma of the breast invading the parotid parenchyma. Chemotherapy combination of capecitabine plus vinorelbine was performed. The evolution was marked by the increase and ulceration of the mass associated with active bleeding (Figure 1) responsible for a decrease in hemoglobin with a level of 5 g/dl. The patient was transfused by two packed red blood cells and trusted us for radiotherapy. Computed tomography revealed a heterogeneous mass of the right parotid measuring 5 cm (Figures 2A and 2B). Haemostatic radiotherapy was given at a dose of 13 Gy in two fractions. Three months after the end of radiotherapy and 12 months after the initial diagnosis, the patient was alive with a stabilization of the parotid mass and disappearance of the bleeding.

Discussion
The parotid metastasis is rare accounting for 9% to 14% of parotid tumors [2]. We select two types of parotid metastases according to their method of spread: lymph node metastases where the neoplastic cells were found in the intra-glandular and peri-glandular lymph nodes of the parotid gland originating from the head and neck tumors, mainly from squamous cell carcinomas and melanomas, and parenchymal metastases by hemotogenous spread [3]. In order of frequency, these tumors were described: bronchial carcinoma, renal cancer, mammary carcinoma, colonic carcinomas, carcinoma of the prostate, carcinoma of the stomach and sarcoma of the uterus [3]. Their frequency was estimated to be 1.8% to 4% of secondary parotid tumors [4]. Dissemination of the breast cancer to the parotid gland is rare. Among 34 patients with parotid metastasis, two of them had a breast origin [5].
The FNAC permitted to apply the positive diagnosis in 41% of the cases that were published in the literature (10 patients). The biopsy was performed in 21% of cases. Our patient had a biopsy. The FNAC is not current practice in our country yet. Metastatic disease to the parotid gland presents a diagnostic problem [18]. The morphological and immunocytochemical characteristics between a primary salivary duct carcinoma and a metastatic ductal breast carcinoma are similar [18]. The association of negative estrogen receptor and intensive staining for carcinoembryonic antigens (ACE) orientate towards salivary duct carcinoma [2,24]. Some authors believe that the presence of a clinical history of a breast carcinoma asserts the diagnosis of parotid metastases [2]. In our case, the diagnosis was made on the clinical presentation and morphological features. The optimum treatment of a patient with a parotid metastasis from breast origin is not well established given the rarity of the case. It depends on the patient's condition and the stage of the disease ( Table 1).
The surgery represents the treatment of choice when feasible. An appropriate parotidectomy with negative margins and with preservation of the facial nerve when possible is preferred [21]. Most authors suggest a superficial parotidectomy when disease is clinically limited to the superficial lobe [4,25]. It was successful in providing control local in most cases [21]. A total or radical parotidectomy is reserved when the deep lobe or the facial nerve are involved [4,21]. Lymph node dissection is required in the presence of clinical or radiological adenopathy. Prophylactic lymph node dissection is not recommended. Postoperative radiotherapy is recommended to improve local control [4]. Some authors prefer chemotherapy to remove occult and microscopic metastases and indicate radiotherapy in case of larger tumor or close surgical margins [13]. The local control is essential; it helps to avoid morbidities secondary to facial paralysis, ulceration and bleeding of the mass. Our patient was in an advanced stage, she had chemotherapy and palliative radiotherapy. The prognosis of patients presenting with parotid gland metastasis from a distant primary tumor is usually poor, with a 5-year survival rate of 10%. It depends on the type of the tumor and the stage of the disease [2].

Conclusion
A parotid mass in a patient with a history of mammary carcinoma must be considered as a metastasis. It is an extremely rare and aggressive entity with a poor prognosis. A multimodal treatment combining surgery, radiotherapy and chemotherapy should be given every time it seems possible in order to get a better local control and a good quality of life.