Ductal carcinoma was first described in 1968 [1]. This is an aggressive adenocarcinoma that resembles high grade ductal mammary carcinoma. This epithelial tumor is rare in the salivary glands [2-4]. In this article, we reported two cases discussed in view of the literature data.

Case 1

A 69-year-old patient was referred to our department for painful swelling of the left parotid area. On examination, the swelling was firm, well mobile and not fixed. The patient presented with House grade III facial palsy. The lymph node areas were free. The MRI showed a blurred swelling, measuring approximately 45mm, developed at the expense of the exofacial part of the parotid gland and taking moderately contrast (Figure 1).  

4.5cm. a: axial T2 view: isosignal; b: axial T1 slice after injection of gadolinium: moderate contrast enhancement.

The treatment consisted of a non-conservative total parotidectomy of the facial nerve (because the facial nerve was invaded) with ipsilateral selective lymph node dissection (T3N0M0) (because the extemporaneous histology was in favor of a malignant etiology). The definitive histological examination was in favor of a ductal carcinoma with excisional margins greater than 1 cm but with the presence of peri-nervous sheath. The lymph nodes removed during the surgery were healthy with a capsular rupture. The excisional margins being healthy, with adjuvant postoperative radiotherapy (60Gy). The patient was in recurrence-free survival after seven years of monitoring.

Case 2

 A 70-year-old patient was referred to our department for a swelling that had been developing for two years in the left parotid area. On examination, the swelling was hard and not very mobile. Facial function was normal. The lymph node areas were free. MRI showed a multinodular exofacial parotid tumor of about 6cm, in T1 iso signal, enhanced at the periphery by the injection of gadolinium and in T2 hypersignal (T3N2M0) (Figure 2). The treatment had been surgical (total conservative parotidectomy of the facial nerve and ipsilateral modified radical cervical recess because the extemporaneous examination was in favor of a malignant etiology). The definitive histological examination was in favor of a ductal carcinoma without lymphatic embolus or peri-nerve sheathing. The lymph nodes removed during the surgery were healthy. The resection margins were healthy but less than 1 cm (and even less than 5 mm on some sections), which led us to perform postoperative radiotherapy (70 Gy by an IMRT technique) (Figure 2). After eight years of monitoring, the patient was surviving without recurrence.

Figure 2: MRI of a 6cm left parotid malignancy: T2 hypo-signal - enhanced after injection of gadolinium and T2 hypersignal - Irregular contours - Adjacent infiltration: the parotid tumor presents a voluminous para-pharyngeal development, pushing back the para-pharyngeal fat inside.

Ductal carcinoma represents 0.2 to 2% of parotid tumors [2], and 6 to 10% of parotid cancers [3]. It usually occurs in the fifth or sixth decade with an average age of 60 years [3]. It preferentially affects men with a sex ratio of two men to one woman. In about 20% of cases, ductal carcinoma of the salivary glands develops from a benign pre-existing lesion. It can result from the degeneration of a pleomorphic adenoma, for example [3,4]. Macroscopically, it is a well-defined, yellowish or greyish-white tumor that may be nodular, multinodular, cystic or infiltrating surrounded by fibrosis with areas of hemorrhage, necrosis and cystic degeneration [3]. Intratumoral calcifications can be found [3,5]. The comedo-necrotizing, papillary and cribriform histological forms are most often encountered [4,6]. There is also an intracanal cell proliferation with an eosinophilic cytoplasmic nuclear polymorphism with some mitosis and an increase in the nucleo-cytoplasmic ratio [3]. The differential diagnoses are mucoepidermoid carcinoma and breast adenocarcinoma metastasis. In case of doubt, the study of estrogen and progesterone receptors and research into the immunohistochemistry of the HER-2 protein may be useful for diagnosis [7]. The most common clinical presentation is that of a rapidly progressive parotid swelling, most often painful [3], hard on palpation, measuring approximately 3 cm and reaching 9 to 10 cm at the time of diagnosis [6] . Facial paralysis, indicative of the local aggressiveness of the tumor, is found in almost half of cases at the time of diagnosis [6]. Lymph node involvement is also observed in 40 to 80% of cases [4]. Radiologically, calcifications can be found at the level of the primary lesion [3]. On MRI, it is a uni- or multinodular tumor in T1 isosignal, T2 isosignal, the signal of which is greatly enhanced by the injection of gadolinium (Fig. 1 and 2). Its invasive nature requires radical treatment. It is mainly based on surgical excision by total parotidectomy with or without sacrifice of the facial nerve depending on its involvement, associated with ipsilateral lymph node dissection. The locoregional failure rate is high [4]. Invaded or insufficient resection margins, the existence of lymphatic embols, perinervous invasion, extraparotid and / or lymph node invasion, local and / or regional recurrence and the existence of metastases are elements unfavorable to the prognosis of survival [4.8-10]. In these cases, postoperative radiation therapy is required. Finally, chemotherapy is generally reserved for metastatic forms. A better prognosis is observed for tumors measuring less than 2 cm [4,8]. The five-year recurrence-free survival rate is around 30% [2,6,9,10].

 Parotid ductal carcinoma is an aggressive malignant tumor whose treatment is primarily surgical. Adjuvant radiotherapy is for advanced forms.

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