gms | German Medical Science

Objective: The presence of inflammation and demyelination in a central nervous system (CNS) biopsy points towards a limited, yet heterogeneous group of pathologies, of which multiple sclerosis (MS) represents the principal consideration. Inflammatory demyelination has also been reported in patients with clinically suspected primary central nervous system lymphoma (PCNSL) especially when steroids had been administered prior to biopsy acquisition. The histopathological changes induced by corticosteroid treatment can range from mild reduction to complete disappearance of lymphoma cells. It has been proposed that in the absence of neoplastic B cells these biopsies are indistinguishable from MS, yet despite the clinical relevance, no histological studies have specifically compared the two entities.

Methods: In the present work we analyzed CNS biopsies from eight patients with inflammatory demyelination in whom PCNSL was later histologically confirmed, and compared them with nine well defined early active multiple sclerosis lesions. Formalin-fixed, paraffin-embedded CNS biopsy material was obtained from the archives of the Institute of Neuropathology, Göttingen. Tissue sections were analysed using standard histochemical and immunohistochemical techniques. Statistical analysis and plotting was performed using the R software.

Results: In the patients with steroid-treated PCNSL (ST-PCNSL) the interval between first and second biopsy ranged from 3-32 weeks; all of the patients had received corticosteroids before the first, but not the second biopsy. ST-PCNSL patients were older than MS patients (mean age: ST-PCNSL: 62±4 years, MS: 30±2 years), and histological analysis revealed numerous apoptoses, a patchy rather than confluent pattern of demyelination and a fuzzy lesion edge. The loss of Luxol fast blue histochemistry was more profound than that of myelin proteins in immunohistochemistry, and T cell infiltration in ST-PCNSL exceeded that in MS by around 5-fold (p=0.005).

Conclusion: Our data indicate that the extent of inflammation and the pattern of demyelination, even in the absence of B cell blasts, suffice to raise the diagnostic suspicion of an underlying lymphoma and may serve to distinguish it from classical autoimmune inflammatory demyelination.