Menke, David

Abstract Intravascular lymphoma (IVL) is a rare extranodal non‐Hodgkin lymphoma. We performed a retrospective analysis of 55 IVL patients who were treated at our institution 2003–2018. Median age at diagnosis was 68 years, and 64% were males. The most frequent presenting symptoms were skin rash 43% and weight loss 30%. MRI brain on IVL patients with CNS involvement (CNS‐IVL) showed multifocal involvement in 76% (13/17). 89% (17/19) of non‐CNS‐IVL patients with abnormal FDG‐PET had biopsy of an avid lesion resulting in definitive diagnosis. The top diagnostic biopsy site was the bone marrow (45%). 56% had multiorgan involvement. Based on CNS involvement, 36.5% (20/55) had CNS‐IVL and 63.5% (35/55) had non‐CNS‐IVL. CNS‐IVL group consists of clinically isolated CNS involvement (CNS‐only IVL) (22%;12/55) and mixed clinical CNS and peripheral site involvement (M‐IVL) (14.5%; 8/55). Non‐CNS‐IVL group consists of clinically isolated skin involvement (skin‐only IVL) (9%; 5/55) and peripheral IVL with or without skin involvement (P‐IVL); (54.5%; 30/55). Skin involvement was predominantly in the lower extremities. Pathologically, 89% (48/54) were B‐cell IVL. Rituximab + high‐dose methotrexate‐based regimen were used in 75% (12/16) of CNS‐IVL patients and RCHOP in 60% (17/28) of non‐CNS‐IVL patients. Estimated 5‐year progression free survival (PFS) and overall survival (OS) for the entire cohort were 38.6% and 52%, respectively. Skin‐only IVL was associated with excellent survival. Platelet count <150x10 9 /L, age > 60Y, and treatment without Rituximab were poor prognostic factors. Further research is necessary to identify novel therapies.

AbstractThis case illustrates an unusual presentation of paraneoplastic myositis in stage IV follicular lymphoma managed with high‐dose steroids, a previously unreported entity in the literature.

Hairy cell leukemia (HCL) is a low grade B-cell lymphoproliferative disorder that typically presents with splenomegaly, cytopenias, and diffuse bone marrow infiltration. There have been few cases in the literature of HCL presenting as lymphomas in extra-nodal locations, such as soft tissues and bones without circulating leukemic cells, splenomegaly, or iliac crest bone marrow involvement. We present an additional case presenting as a thoracic mass, and discuss potential diagnostic pitfalls and management of these rare cases.

Key Points An international panel established the first ever diagnostic criteria for iMCD based on review of 244 clinical cases and 88 tissue samples. The criteria require multicentric lymphadenopathy with defined histopathology, ≥2 clinical/laboratory changes, and exclusion of iMCD mimics.