Med Ultrason 2021:0, 1-3 Online frst DOI: Ahead of print Mucosa-associated lymphoid tissue lymphoma of the parotid gland – a case report Delia Muntean 1 , Sorin Dudea 2 , Manuela Lenghel 2 , Carolina Solomon 2 , Teodora Iuga 3 , Horațiu Rotar 4 1 Emergency County Hospital Cluj-Napoca, Radiology Department, 2 “Iuliu Hațieganu” University of Medicine and Pharmacy, Radiology Department, 3 Emergency County Hospital Cluj-Napoca, Maxillofacial Surgery and Implantology Department, 4 “Iuliu Hațieganu” University of Medicine and Pharmacy, Maxillofacial Surgery and Implantology Department Received 13.12.2020 Accepted 14.03.2021 Med Ultrason 2021:0 Online frst, 1-3 Corresponding author: Manuela Lenghel, MD, PhD Radiology Department, “Iuliu Hațieganu” University of Medicine and Pharmacy 3-5 Clinicilor Str., 400006, Cluj-Napoca, Romania Phone: +40740.423.025 E-mail: lenghel.manuela@gmail.com Introduction Primary salivary gland lymphoma is uncommon, ac- counting for 1.7-3.1% of all salivary gland malignancies [1]. Lymphomas are generally classifed into Hodgkin and Non-Hodgkin Lymphoma (NHL) and can be further subdivided into intranodal or extranodal types. Mucosa- associated lymphoid tissue (MALT) lymphoma repre- sents a low-grade marginal zone B-cell NHL affecting various extranodal sites, such as gastric mucosa, lacrimal and salivary glands [2,3]. Case report We report a case of a 71-year-old woman referred to the Oromaxillofacial Surgery Department for facial asymmetry and a progressive painless hard swelling of the right parotid gland, frst noticed three months before admission. In 2013, the patient was previously treated for diffuse large B-cell NHL (DLBCL), Ann Arbor stage III with cervical, axillary, and retroperitoneal lymph nodes involvement. The patient underwent chemotherapy with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) and achieved complete re- sponse assessed on the annual imaging follow-up. The frst-line performed imaging method was ul- trasonography (US) which revealed a hypoechoic, het- erogeneous, irregular mass with anarchic vascularity on colour Doppler US and soft appearance with small stiff areas at real-time elastography (fg 1). No calcifcations or necrotic areas were encountered. Based on the US ap- pearance and the patient’s clinical history, a malignant lesion was suspected, with a high possibility of a lym- phoma variant. Contrast-enhanced MRI features were also consistent with malignancy. MRI demonstrated an ill-defned mass within the superfcial lobe of the right parotid gland, presenting marked diffusion restriction (ADC 0.588 x 10 -3 mm 2 /s) and increased homogenous enhancement (fg 2). Fine-needle aspiration biopsy was performed and Abstract Mucosa-associated lymphoid tissue (MALT) lymphoma of the parotid gland is a rare entity among head and neck tumours. We report a case of a patient with a medical history of diffuse large B-cell Non-Hodgkin Lymphoma with complete remission following chemotherapy, who presented seven years afterwards with a progressive painless hard swelling of the right parotid gland. Ultrasonography followed by contrast-enhanced MRI features was consistent with a malignant tumour. Consequently, fne and core needle aspiration biopsy were performed under ultrasound guidance and the fnal histopathological result was MALT lymphoma of the parotid gland. The most important particularity of the case is the sequential development of two dif- ferent histopathological types of Non-Hodgkin Lymphoma, both of B-cell lineage. Keywords: parotid; mucosa-associated lymphoid tissue lymphoma; ultrasound; MRI DOI: 10.11152/mu-2957