Invasive micropapillary salivary duct carcinoma mixed with mucin-rich salivary duct carcinoma in minor salivary gland: A rare case report

Background Invasive micropapillary salivary duct carcinoma (SDC) is a rare variant of SDC. Although several cases involving major salivary glands have been reported, no cases arising de novo in minor salivary glands have been reported to date. Here we report the first case of invasive micropapillary SDC that arose in a minor salivary gland of the parapharyngeal space. Methods A 72-year-old male patient presented with an enlarging mass in the left parapharyngeal region along with trismus and swollen lymph nodes. Clinical examinations and biopsy findings were suggestive of a salivary gland malignant tumor with regional lymph node metastases. The tumor, therefore, was excised with partial mandibulectomy with unilateral radical neck dissection. Results Histologically, the tumor consisted of an invasive micropapillary growth pattern of SDC and mixed with mucinous component of SDC. Local recurrence and lung metastasis developed, and the patient died of disease 13 months after the initial treatment. Conclusions We describe the clinical and histologic features of this extremely rare case of minor salivary gland SDC that was histologically characterized by the presence of both invasive micropapillary growth pattern and mucinous component.