Focal, Symptomatic Bone Marrow Lesions in Waldenström Macroglobulinaemia Characterised By Dense Infiltration with Lymphoplasmacytic Lymphoma: A Newly Defined Indication for Systemic Treatment

• Published in: Blood 2020-11, Vol.136 (Supplement 1), p.3-4
• Main Authors: Arulogun, Suzanne, Abbasi, Maaz Ali, Pomplun, Sabine, O'Neill, Aideen Therese, Wan, Simon, Kayani, Irfan, D'Sa, Shirley
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2020-138716

BACKGROUND Waldenström Macroglobulinaemia (WM) is an indolent, IgM-producing lymphoplasmacytic lymphoma (LPL) that infiltrates bone marrow (BM) and other tissues. Only symptomatic patients (with IgM-related complications, cytopenias, constitutional symptoms, bulky extramedullary disease) require treatment. Symptomatic BM lesions are not a recognised manifestation of WM and, if present, may raise the possibility of high-grade transformation. AIMS To characterise the clinical, radiological and histological features of focal bone marrow lesions (FBML) identified in WM patients with unrelenting pain in bones and/or joints, and outline implications for treatment. METHODS This study retrospectively reviewed investigations performed at the time of FBMLpresentation, including MRI of the site of pain, total body FDG-PET/CT, review of histology from BM trephine biopsy of the posterior superior iliac spine (PSIS) and CT-guided core biopsy of the identified FBML, and routine blood panels. RESULTS The 6 patients identified (Table 1) presented with localised skeletal pain at different stages of their WM disease course: 1 at initial WM diagnosis, 1 after 10 years of observation, 3 in remission following R-chemotherapy, and 1 during active treatment with R-chemotherapy. Median age at diagnosis of WM was 57 years (41-64 years). Median time from diagnosis to presentation with FBML was 28 months (0-120 months). MRI demonstrated well-defined areas of abnormal signal within the medullae of symptomatic bones and no evidence of cortical or trabecular bone involvement (Fig. 1A), with T1 hypointensity, diffusion restriction and mild STIR hyperintensity in excess of background BM changes. The FBML showed a predilection for the lower limbs (knees, ankles and/or feet involvement in 3 patients, 50%) and periarticular spaces (5 patients, 83%). They were CT-occult and only mildly FDG-avid. In all cases, core biopsies of the FBML showed heavy BM infiltration with diffuse interstitial infiltrate of small, mature lymphocytes (Fig. 1B, 1C) expressing CD20, CD79a and IgM; CD138 staining highlighted scattered interstitial plasma cells (