Background: Adenoid cystic carcinoma (ACC) is a common malignant tumor of salivary gland. The lung and liver are frequent sites of distant metastasis. Liver metastasis as the initial clinical manifestation of sublingual gland ACC is very rare.
Case summary: A 51-year-old Chinese woman presented with a painless mass in the right lobe of liver. The tumor was composed of ductal cells and myoepithelial cells with a morphology including tubiform and cribriform structures. Immunostaining results showed ductal cells positive for CK7, CK14, CK19, CD117, and 34βE12, and negative for MYB, vimentin, ER, PR, and CEA. The myoepithelial cells were positive for p63, calponin and CK5/6. Metastatic salivary ACC was considered, and a sublingual gland mass was revealed by computed tomography. Histological evaluation confirmed primary sublingual gland ACC. Fluorescence in situ hybridization (FISH) did not find an MYB-NFIB fusion gene in specimens from either the primary or metastatic ACC tumors. The sublingual gland ACC relapsed in 20 mo. The recurrent lesion disappeared following local radiation therapy and computed tomography-guided radioactive seed implantation. The patient remains in good condition until now.
Conclusion: Metastatic sublingual gland ACC with initial clinical manifestation as a liver mass is very rare, and was pathologically confirmed in this patient by its histological appearance. Primary hepatic tumors and metastatic carcinomas should be included in the differential diagnosis. Immunohistochemical detection of MYB protein and MYB-NFIB fusion gene detection by FISH can be helpful, but occasional negative results confuse the diagnosis.
Keywords: Adenoid cystic carcinoma; Case report; Differential diagnosis; Fluorescence in situ hybridization; Immunohistochemistry; Liver metastasis; Sublingual gland.
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