We describe a patient with a primary diffuse large B-cell lymphoma of the central nervous system who developed a localized testicular relapse after 8 years.Both tumours lacked HLA-DR expression, the relapse additionally lost HLA class I expression.Immunoglobulin heavy chain gene rearrangements were identical in both lymphomas with extensive better waters xl7000 and ongoing somatic hypermutations resulting here in extensive idiotype modulation.
We hypothesize that these immune sanctuaries initially provided a safe haven for the tumour cells.When the environment becomes more permissive for an anti-tumour response, the continuous idiotype modulation and progressive loss of HLA expression on the tumour cells facilitates further immune escape.