Metastatic hepatocellular carcinoma mimicking acinic cell carcinoma of the parotid gland: a case report.

Background: Fine needle aspiration (FNA) is becoming increasingly important in the diagnosis of salivary gland lesions. One of the diagnostic difficulties that arise from FNAs is the distinction between primary and metastatic tumors. We describe a case where a right cheek/parotid mass was originally diagnosed as acinic cell carcinoma (ACC) upon biopsy. Later, an FNA resampling of the mass was diagnosed as hepatocellular carcinoma (HCC), and indeed, a subsequently performed computed tomography scan showed that the patient had a previously unknown liver mass.

Case: A 75-year-old man presented with a pathologic mandibular fracture. An initial needle core biopsy of the lesion showed neoplastic cells with abundant granular cytoplasm and prominent nucleoli and was diagnosed as ACC. The patient shortly thereafter developed an abdominal lesion that upon FNA was found to be cytologically similar to the parotid mass. Immunohistochemical stains showed that the abdominal mass was Hep Par 1 positive, and HCC was diagnosed. An FNA resampling of the parotid lesion was then performed, and stains showed that it was also Hep Par 1 positive. The lesion was rediagnosed as metastatic HCC and not ACC. Radiologic scans of the patient then showed a liver mass as well as multiple bony lesions.

Conclusion: A right cheek/parotid mass initially diagnosed as ACC was later found to be metastatic HCC. At times, the judicious use of immunohistochemical stains is necessary to distinguish primary salivary gland neoplasias from metastatic tumors.