Pleural fluid metastases of salivary duct carcinoma: A case report and review of the literature
The present case report is about a 76-year-old male patient, with a 9-year history of SDC metastatic to the right testicle and brain, who presented at our institution for cryoablation of suspicious lung nodules and subsequently had a recurrent left pleural effusion. He was originally diagnosed at age 67 with a 1.5 cm right submandibular SDC, which showed large polygonal epithelioid cells with prominent nucleoli and abundant granular eosinophilic cytoplasm, arranged in a cribriform pattern with central necrosis []. Perineural and lymphovascular invasion were noted. Immunohistochemical stains showed positivity for human epidermal growth factor receptor-2/neu (HER2/neu) and gross cystic disease fluid protein-15 (GCDFP-15) and negativity for estrogen receptor (ER) and progesterone receptor (PR). The patient was treated with local radiation and chemotherapy. At 4 years later, pulmonary micronodules were noted on positron emission tomography and computed tomography (CT) scan, as well as a recurrence in his right testis. He underwent orchiectomy and received additional chemotherapy. The following year, a right occipital lobe metastasis was irradiated and resected. Serial radiographic imaging showed slow progressive growth of the pulmonary nodules.\nAt the time of current admission, the patient was receiving radiation therapy, but not systemic therapy. The most recent chest CT angiogram showed bilateral pulmonary metastases up to 5.4 cm, pleural implants and a nodular rind of metastatic disease along the left mediastinal reflection. Following cryoablation of the three largest nodules, ultrasound-guided thoracentesis of a left pleural effusion yielded 350 cc of bloody, opaque fluid. Cytological evaluation of cytospin preparations and cell block revealed large, pleomorphic epithelioid cells in small clusters with subtle cribriform features []. The cells displayed large oval nuclei with prominent nucleoli and coarsely granular chromatin. A moderate amount of finely granular apocrine-type cytoplasm was present.\nImmunohistochemical stains [] performed on the cell block were positive for androgen receptor (AR) (panel A), HER2/neu (panel B), Moc31 (panel C) and GCDFP-15 (panel D). These cells were also positive for BerEp4 and were negative for ER and PR. The malignant cells were not present on deeper cuts for evaluation of mammaglobin and B72.3. The morphologic and immunohistochemical profile was similar to the original submandibular pathology and a diagnosis of metastatic SDC was rendered.