Acinic Cell Carcinoma of the Salivary Gland with Metastatic Spread to the Pancreas
In 2005, a 46-year-old woman presented with several years of progressive left jaw pain and swelling and ultimately developed partial left-sided facial paralysis. In August 2005, she underwent a left total parotidectomy with partial sacrifice of the left facial nerve. Histopathologic examination of the deep left parotid gland showed a thinly encapsulated low-grade salivary gland neoplasm. Tumor cells exhibited round to oval nuclei with inconspicuous nucleoli and basophilic granular cytoplasm that is characteristic of well-differentiated AcCC. Surgical margins were negative. In April 2008, the patient developed a local recurrence in the left neck, confirmed by fine needle aspiration. On May 29, 2008, she underwent surgical excision of the left neck mass with negative margins and one sampled lymph node negative for disease. No other treatment modalities were given. Two years later, the patient developed a second local recurrence, and in June 2010, a 5 × 3-mm mass consistent with recurrent AcCC was removed from the posterior triangle. In October 2010, a surveillance PET/CT scan revealed a 1-cm hypermetabolic nodule between the left styloid process and the tip of the mastoid. Fine-needle aspiration findings were consistent with a third local recurrence of AcCC. In January 2011, the patient had a left posterior neck exploration surgery with left neck dissection. Pathology revealed a single focus of recurrent disease in a lymph node measuring 2.6 cm. Surgical margins were negative but narrow at <0.1 cm. Three other lymph nodes sampled were negative for metastatic disease. The patient did not receive any adjuvant therapy and was placed on expectant observation.\nIn August 2011, the patient presented to our institution for a second opinion regarding management of a fourth local recurrence presenting as an enlarging, asymptomatic neck mass below the left mandible. On physical exam, a single 1-cm non-tender nodule was palpable just below the mandible, overlying the left sternocleidomastoid muscle. She had no other palpable masses or lymphadenopathy present. An MRI scan of the face and neck revealed a 1.3-cm mass in the previous operative bed in addition to a 1.4-cm enhancing mass at the skull base. CT of the chest, abdomen, and pelvis showed no evidence of distant metastatic disease. On August 29, 2011, the patient had a wide local excision of a locally recurrent AcCC measuring 1.5 × 1.3 × 1.1 cm (fig. ). Margins were negative. The second skull base mass seen on imaging was not amenable to surgical resection. The patient subsequently received concurrent chemoradiation therapy to the left neck from October through December 2011 with a total dose of 7,000 cGy in 35 fractions with weekly cisplatin. A surveillance PET/CT scan performed in March 2012 showed no evidence of disease.\nIn August 2012, the patient was admitted to a local hospital for epigastric pain, nausea, and vomiting, and was diagnosed with acute pancreatitis. An outside MRI scan of the abdomen revealed a mass in the head of the pancreas (fig. ). Esophagogastroduodenoscopy and an endoscopic ultrasound with biopsy of the mass were performed, and pathology revealed a well-differentiated neoplasm consistent with metastatic AcCC of salivary gland origin. A PET/CT scan showed minimal fluorodeoxyglucose avidity corresponding with the pancreatic mass but no other areas of active disease and no evidence of local recurrence in the head and neck. On September 21, 2012, the patient underwent a laparoscopic metastasectomy. Microscopic examination revealed a 3.0-cm lobulated neoplasm set within a bed of desmoplastic stroma of the pancreatic neck (fig. ). These tumor cells were morphologically compatible with the excised primary and recurrent tumors resected. Moreover, an immunohistochemical stain for trypsin (Meridian Life Science, Inc., Memphis, Tenn., USA) was negative, essentially ruling out the possibility of acinar cell carcinoma of the pancreas and confirming the diagnosis of metastatic AcCC to the pancreas. Perineural invasion was present. Surgical margins were negative. Multiple (24) regional lymph nodes were negative for metastatic disease. The patient recovered well and resumed routine surveillance. To date, she has had no evidence of disease progression.