Histopathogenesis of chronic sialectatic parotitis as precursor of benign lymphoepithelial lesion (Sjogren's syndrome)

Background: Chronic sialectatic parotitis (CSP) is classified as a characte ristic form of chronic recurrent parotitis the etiology and pathogenesis of which still remains unclear. The multiplicity of different therapeutic adv ices, especially the permanent failure of antibiotic treatment, underlines the lack of an appropriate causal therapy. Case report: Detailed histopatho logical investigations of an 41-year old woman were possible over a seven-y ear period. These follow-up observations enabled clarification of the histo pathogenesis of CSP by means of immunohistochemistry. Results: During the c ourse and development of CSP different stages can be observed: The initial phase is characterised by mild infiltration of B-lymphocytes (CD20, CD45 R) and plasma cells in the environment of ectatic ducts. Progredient stages s how neogenetic lymph follicles periductular as well as metaplasia of the du ctal epithelium. Terminal phases of CSP are characterised by near-total lym phatic transformation of parenchyma, follicular lymphatic hyperplasia (KiM4 ) and myoepithelial proliferation. In this phase myoepithelial sialadenitis (MESA, i.e. benign lymphoepithelial lesion, possibly part of Sjogren's syn drome) develops. Beyond it low grade non-Hodgkin's lymphoma of the MALT-Typ e of the submandibular gland occurred finally. Conclusions: CSP presents as a precursor of MESA. Immunohistological detection of follicular dentritic network (KiM4) within extensive lymphatic hyperplasia periductular demonstr ates overshooting humoral immune reaction of B-lymphocytes. Hence, CSP shou ld be classified with regard to pathogenesis as an immunopathological disor der of the MALT system.