Primary dural lymphoma: A novel concept of heterogeneous disease

Spinal primary dural lymphoma (PDL) is uncommon with a total of 37 previous well‐documented cases reported, including one diagnosed in the authors' institution. More recently we encountered an additional case of spinal PDL that, similarly to our previous case, was grade 1–2 follicular B‐cell PDL. Our two cases were diagnosed over a 3‐year interval in a 72‐year‐old female and a 74‐year‐old male, respectively. An exhaustive literature review on PDL was performed consequently to reveal that: (i) spinal and cerebral sites of involvement by PDL are constantly mutually exclusive; and (ii) unlike cerebral PDL, which is usually of marginal zone B‐cell type, only two of the 38 cases of spinal PDL were diagnosed as such, diffuse large B‐cell lymphoma being the most commonly encountered type in the spine. This divergence infers that, in contrast to the prevailing concept that PDL is a unique disease group, PDL appears to be rather heterogeneous with a difference in predilection of lymphoma type for the anatomical site of dural involvement. Such a site‐specific lymphoma‐type predilection phenomenon, well‐recognized in other organ systems, has not been acknowledged in PDL. This report brings new insights into PDL, and may contribute to a better understanding of nervous system pathophysiology and lymphoma classification.