1626 Primary Adenoid Cystic Carcinoma Presenting as Distant Metastasis to Ascending Colon

Abstract

INTRODUCTION: Salivary gland tumors are rare, often benign, mostly originating from the parotid gland. Tumors can also arise from submandibular and sublingual glands, and while these tumors tend to be more rare, they are more often malignant. Salivary gland tumors usually metastasize to the lung, bone, and liver. CASE DESCRIPTION/METHODS: A 77-year-old Albanian male with history of a right-sided mandibular abscess s/p drainage in 2015 presented with confusion and abdominal pain. Labs were unremarkable. He underwent CT head, which was concerning for an occipital lesion, for which he proceeded with an MRI brain that revealed multiple intracranial lesions concerning for metastatic disease. He then had a CT Abdomen/Pelvis that revealed several hepatic lesions, innumerable pulmonary nodules, and an area of focal thickening and enhancement of the proximal ascending colon. Bone scan revealed likely metastasis to the L5 vertebral body. His CEA was 4.7 and CA 19-9 was 43.6. AFP was 1.7. He then had a colonoscopy, which was significant for 2 polyps in the descending colon, 2 umbilicated polyps in the transverse colon, a 4 mm sessile polyp in the transverse colon, and a submucosal and ulcerated non-obstructing mass in the proximal ascending colon distal to the ileocecal valve. Pathology showed small, round, blue cells with trabecular growth pattern and necrosis, consistent with invasive, poorly differentiated carcinoma with basaloid features. In addition, the immunohistochemistry was positive for CK7 and Sox10, focally positive for S100, and weakly positive for CD 117, all suggestive of an adenoid cystic carcinoma. Treatment first consisted of palliative radiation to his CNS lesions, a dexamethasone taper, and an Oncology consult for consideration of palliative chemotherapy. He was offered palliative paclitaxel and carboplatin, however he ultimately decided to return to Albania and forego treatment. DISCUSSION: This patient likely had undiagnosed, malignant, primary salivary gland cancer for many years; despite having his mandibular ‘abscess’ drained several years prior. In addition, the lesion metastasized to several uncommon locations, notably the brain and colon, which are the 2 sites that ultimately produced symptoms that prompted him to receive further medical care. Salivary gland tumors must be considered in patients presenting with head and neck swelling, and proper diagnostic workup must be obtained. In addition, uncommon sites of metastasis, such as colon, must be considered during staging of disease.

Colonic Metastasis of Adenoid Cystic Carcinoma 19 Years after the Primary Tumor Resection

“…When ACC is identified in the colon, efforts should be made to look for distant history of primary ACCs, such as 19 years ago in our patient. Interestingly, in one of the publications, the patient only had remote history of mandibular “abscess,” which could be an undiagnosed ACC [ 4 ].…”

“…The most common primary site of colorectal metastasis is the breast, followed by the lung and malignant melanoma [ 1 ]. Metastatic adenoid cystic carcinoma (ACC) in the colon is rare, with only a few case reports available [ 2 – 4 ]. Here, we report a case of ACC metastatic to the colon 19 years after resection of the primary tumor, to broaden the differential diagnosis of colorectal malignancies and to better understand the clinical, histological, and molecular features of ACC.…”