Intravascular large B-cell lymphoma with bone marrow involvement at presentation and haemophagocytic syndrome: two Western cases in favour of a specific variant.

AIMS: To report two cases of an unusual form of intravascular lymphoma, characterized by bone marrow involvement at presentation with haemophagocytic syndrome. METHODS AND
RESULTS: We describe the clinicopathological features of two patients with intravascular lymphoma primarily involving bone marrow. Both patients complained only of fever with pancytopenia and reactive haemophagocytic syndrome. Diagnosis was made on bone marrow examination, which showed large tumour cells of B-cell lineage confined within the lumen of sinuses.
CONCLUSION: These two cases and five previous reports could represent a variant of intravascular lymphoma, characterized by early involvement of bone marrow without dissemination to other organs. This form of intravascular lymphoma, called IVL-HS, seems to be an 'Asian' variant with a high prevalence in Asian people and a very low prevalence in Western countries. At a practical level, bone marrow biopsy may be useful in the diagnosis of intravascular lymphoma when the clinical presentation is restricted to fever of unknown origin with a reactive haemophagocytic syndrome.