Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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October 18, 2018
Primary bilateral parotid Non-Hodgkin lymphoma (MALT Type)
- Background
- Parotid primary NHL represents 2-5% of malignant parotid tumors
- Etiology is probably multifactorial
- Increased risk is reported in patients with autoinmune disorders or inmunosupression
- Sjögren syndrome increases risk up to 40 times. MALT type is the most frequent histological subtype
- Clinical Presentation
- Slowly growing painless parotid mass +/- cervical lymph node enlargement is the most common clinical presentation
- It may be associated with fever, weight loss and/or night sweats
- Key Diagnostic Features
- Infiltrating parotid nodules or masses usually solid and cystic with homogeneus intermediate signal on T1W, low or intermediate signal on T2W and mild or moderate homogeneus enhancement
- Due to the high cellular density, the lesions usually show low ADC values
- Differential Diagnosis
- Benign lymphoepithelial lesions related to HIV: solid-cystic lesions that enlarge the parotid glands, usually associated with cervical lymph node enlargement and nasopharyngeal lymphofollicular hyperplasia
- Sjögren syndrome: bilateral parotid enlargement with small or big cysts +/- lymphoid aggregates (solid nodules / masses)
- Warthin tumor: painless parotid mass (unilateral, multifocal, or bilateral) with solid, cystic, or mixed pattern. Does not have cervical lymph node enlargement
- Metastatic parotid lymph node enlargement: multiple, ill-defined solid parotid masses (unilateral or bilateral) +/- necrotic foci
- Treatment
- Surgery: Complete excision of the tumor via superficial parotidectomy on early-stage parotid MALT lymphoma variant
- Chemotherapy and radiotherapy is the treatment of choice
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