Adenoid cystic carcinoma of the salivary gland metastasizing to the pericardium and diaphragm: Report of a rare case.

Background: Adenoid cystic carcinoma (AdCC) is an uncommon malignancy of the salivary gland characterized by slow growth, increased risk of recurrence and poor prognosis. The annual incidence in the United States is approximately 1200 cases per year and rarely involves the body cavities.
Case Presentation: We present a case of a 48-year-old male diagnosed with AdCC of the left submandibular gland. He received his last chemotherapy in 2006 and presented with pleural metastasis. After undergoing pleurectomy and decortication procedure, pericardial fluid and biopsies from the chest wall, sixth rib, diaphragm, pleural cavity and pericardium were sent for pathologic evaluation. A diagnosis of metastatic adenoid cystic carcinoma was confirmed, including in the pericardium, pericardial fluid and diaphragm.
Conclusion: AdCC of the submandibular gland is a malignant tumor with a high mortality rate. It is very rare for AdCC to metastasize to the pericardium and diaphragm. Metastasis to uncommon sites such as seen in our case with metastases to the pericardium and diaphragm shows the aggressive and unpredictable nature of this tumor, requiring close follow up, and indicating the need for molecular profile analysis and biomarker-stratified clinical trials.
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