Background and aim Marginal zone lymphomas represent 3% of all lymphomas and are divided into extranodal (ENMZL), splenic and nodal. ENMZL is characterised by indolent natural history, is usually diagnosed in localised stages (70%) and chronic antigen stimulation seems to be involved in its pathogenesis. Typically seen in the 6^th decade of life, it is responsible for 8% of adult non-Hodgkin lymphoma. According to multicentre NHL-BFM studies, the incidence of ENMZL in children is 0.1%, most commonly found in the gastrointestinal tract (44%). The salivary gland is involved only in 5% of paediatric patients, being preceded in 1/3 cases by Sjogren syndrome (SS). Herein, we report a 15-year-old girl with advanced ENZML of salivary glands following SS, a very rare diagnosis in children.

METHOD AND Results Female patient, 13y, presented with enlarged jaw area, was evaluated by an oral-maxillofacial surgeon and cherubism was excluded. Laterocervical ultrasound, head and neck MRI: hypertrophic parotid glands with cystic images, small adenopathies. Based on parotid swelling, dry mouth and eyes, bilateral hypo-lacrimation on Schirmer’s test, positive anti-Ro, anti-La and anti-nuclear antibodies, she was diagnosed with primary SS. At age 15: progressive parotid swelling, no ‘B’ symptoms, leucopenia 3.38 × 10^9/l, anaemia 10.5 g/dl, sedimentation rate 33 mm/h, LDH 225UI (n<200 UI), B2-microglobulin 2.62 mg/L (n=0,9–2 mg/L), normal bone marrow biopsy. Right parotid biopsy, immunohistochemistry and molecular biology: lymphoid proliferation of small-sized monocytoid cells, with lympho-epithelial lesions and marginal zone pattern (incorporating residual reactive germinal centre), CD20+, CD3-, kappa/lambda 5/1, FR2-JH+ in heavy-chain IG. PET-CT scan showed active sites in left parotid gland, supra and subdiaphragmatic lymph nodes. The patient was diagnosed with B-cell ENMZL of parotid glands, stage III A. She received 6 cycles of R-CHOP regimen (rituximab, cyclophosphamide, vincristine, doxorubicin, prednisone), at 3 week interval, had negative PET-CT after 4 and 6 courses and she is in complete remission 6 months after the end of therapy.

Conclution ENMZL of parotid glands following SS is rarely seen, especially in paediatric patients, thus the knowledge about this lymphoma type is limited. It is low-grade and responds well to R-CHOP chemotherapy, even in advanced stages. Nevertheless, regular follow-up is required, as relapses can occur during the course of the disease.