A 73-year-old man was brought to our attention in January 2001 because of a swelling in the right parotid region, which had appeared three years before but had always been neglected by the patient because of its asymptomatic nature. It had apparently grown more rapidly over the previous two months, and a physical examination revealed the presence of a voluminous mass with a regular border that was mobile on the superficial and deep planes, and did not hurt upon palpation. There were no palpable cervical lymph nodes.
Three weeks before, the patient had undergone an ultrasound (US) examination of the neck and salivary glands, and a fine-needle aspiration biopsy revealed a mass on the superficial lobe of the parotid. The biopsy specimen suggested Warthin's tumour, but was negative for malignant cells. The computed tomography (CT) scan made using intravenous contrast medium confirmed the presence of a 3.4 × 2.5 cm mass on the right parotid gland. No pathological lymph nodes were identified (Fig. ).
The patient underwent a right superficial parotidectomy and, as an analysis of a frozen section showed the presence of poorly differentiated carcinoma cells, the surgeon extended the exeresis of the gland to the lower pole, preserving the facial nerve which was unaffected by the neoplasm. There were no right facial nerve deficits after the operation. The surgical specimen (3.5 × 2.5 × 1 cm) had a well-circumscribed, spherical, soft grey nodule with a few small cysts (a typical WT); the inner portion consisted of a harder yellow mass measuring 1.7 cm that proved to be a poorly differentiated carcinoma (Fig. ).
The grey nodule was histologically characterised by a prominent lymphoid matrix with germinal centres. The surface of this lymphoid tissue was covered by papillations of large epithelial cells forming cystic spaces with oncocytic features. The cells were arranged in two layers: the inner layer consisted of cuboid and polygonal cells containing nuclei with prominent nucleoli; the outer layer consisted of tall and sometime ciliated columnar cells, with centrally located pyknotic nuclei and a peripheral fibrous capsule. The oncocytic epithelial component inside the typical WT showed a hyperplastic-dysplastic change confluent with solid undifferentiated neoplasm (Fig ); the malignant epithelial component, which was immunoreactive to an anti-cytokeratin pool (AE1-AE3; Dako), consisted of nests or single cells with a surrounding desmoplastic stroma sometimes infiltrated by small lymphocytes and plasma cells (Fig. ). There were two types of intermitted cells loosing the papillary formation. The first were large cells with hyperchromatic nuclei, prominent nucleoli and thick chromatin along the nuclear membrane, abundant cytoplasm and well-demarcated cell membranes; no intercellular bridges or keratin production could be identified in these areas. The second were smaller eosinophil cells containing numerous eosinophilic granules, with oval nuclei, clumped chromatin and a centrally located eosinophilic nucleolus. The presence of mucin was excluded by PAS and PAS diastase staining of the paraffin blocks. Peripherically, small clusters of tumour cells penetrated the fibrous capsule and infiltrated the surrounding salivary gland.
The postoperative course was uneventful. The patient underwent postoperative radiotherapy because of the results of the histological examination. Now, 20 months after surgery, he is well and and has not experienced any recurrence.
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