Short summary

Today, baseline evaluation with bone marrow biopsy (BMB) is part of the recommendation for patients with newly diagnosed primary CNS lymphoma. Our aim is to evaluate the value of BMB retrospectively in patients with newly diagnosed primary CNS lymphoma.

Rationale

Primary CNS lymphomas (PCNSLs) are extranodal non-Hodgkin´s lymphoma (NHLs) restricted to the CNS, the meninges and/or the eyes. More than 96% of the PCNSL consist of diffuse large B-cell lymphomas (DLBCLs), while T-cell variaties and low-grade lymphomas represent only 1-4% of all cases in the Western countries.

According to The International PCNSL Collaborative Group it is recommended to perform both contrast-enhanced MRI of the brain, contrast-enhanced MRI of the spine (if spinal symptoms are present), as well as ophthalmologic and CSF(cerebrospinal fluid) evaluation.

To detect non-CNS dissemination and the presence of systemic disease, a fluorodeoxyglucose (FDG)-PET scan as well as a bone marrow biopsy should be performed. Before the recommendation from the International PCNSL Collaborative Group was launched, the importance of a complete baseline staging has widely been discussed in the litterature. On one side, a group of scientist argued that a cerebral mass lesion tend to remain localized with little reason to perform CT scans or bone marrow biopsy. This suggestion was followed by other researchers finding 4-6 % systemic dissemination of PCNSL.

Today, baseline evaluation with bone marrow biopsy, is primarily based on an American study from 1995, evaluating 128 patients initially thought to have PCNSL, reporting systemic lymphoma in 3,9% of cases with one patient who had BM involvement. This study enrolled patients from 1975-1994 before the introduction of baseline evaluation with PET/CT scans which has a higher specificity than CT alone. In resent time, CT scan is known to understage patients with aggressive lymphoma, following a risk of missing a systemic lymphoma with CNS involvement.

To date no studies have addressed the presence of concomitant PCNSL and isolated high grade lymphoma infiltration in the bone marrow in the PET/CT era. Consequently, routine bone marrow biopsy is still a part of the staging setting and might hypothetically be omitted after PET/CT rules out systemic disease.

Description of the cohort

• Patients with newly diagnosed DLBCL with CNS involvement

• Patients diagnosed 2002-2020 who has a PET/CT scan at diagnosis.

Data and biological material

Medical records belonging to patients fulfilling the criteria for inclusion will be reviewed for following information:

• Involvement of lymphoma in bone marrow (both concordant and discordant)

• Involvement of systemic lymphoma on PET/CT.

Collaborating researchers and departments

Department of Hematology: Aarhus University Hospital, Aalborg University Hospital, Copenhagen University Hospital, Rigshospitalet, Herlev University Hospital, Zeeland University Hospital, Roskilde