Salivary duct carcinoma of the parotid gland
Right facial swelling.
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Enhancing mass centred on the right deep lobe of parotid gland and bellies of right medial and lateral pterygoid muscles, wrapping posteriorly around the mandibular ramus to extend into the superficial parotid.
Anteriorly the mass extends to the mandible and to abut the right lateral pterygoid plate, but no involvement of the pterygopalatine fossa. Superiorly it extends to involve the right temporomandibular joint.
The patient proceeded to ultrasound guided core biopsy.
MICROSCOPIC DESCRIPTION: The core biopsy shows parotid parenchyma. There is invasive carcinoma, surrounded by fibrous stroma. The tumour forms trabeculae and nests. No glands are noted. The tumour cells are focally crushed. They have enlarged nuclei, conspicuous nucleoli and moderate amounts of pale eosinophilic cytoplasm. There is no obvious keratinisation. No mucous cells are seen. There is no comedo-type necrosis. No evidence of lymphovascular or perineural invasion is identified. The tumour cells are CK7, BER-EP4, GCDFP-15 and androgen receptor positive. They are c-kit, DOG1, PSA, PSAP, p40 and p63 negative. The immunoprofile is consistent with salivary duct carcinoma.
DIAGNOSIS: Parotid core biopsy: Features consistent with salivary duct carcinoma.
Salivary duct carcinomas are rare salivary gland tumours, accounting for 1-6% of malignant parotid gland tumours. It most commonly presents as a rapidly growing mass in elderly men, and is aggressive with extracranial facial nerve involvement, perineural spread and early metastatic disease.