Abstract Details

Title Myopathies associated with large granular lymphocytic (LGL) leukemia

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) P15 - Poster Session 15 (5:30 PM-6:30 PM)

Poster/Presentation
Number 11-003

Background LGL leukemia is a rare leukemia of cytotoxic lymphocytes that includes T-LGL and natural killer (NK)-LGL leukemia. LGL-leukemia was reported in 58% of a single cohort of patients with sporadic inclusion body myositis (sIBM), the most common acquired myopathy after age 50. However, frequency and diagnostic spectrum of myopathies in LGL patients is unknown.

Objective

To identify the spectrum of myopathies associated with large granular lymphocytic (LGL) leukemia.

Design/Methods We retrospectively reviewed 2 cohorts of Mayo Clinic patients: 1) LGL-leukemia patients evaluated between 2003 and 2018; 2) sIBM patients seen and tested for coexisting LGL-leukemia by T-cell receptor gene rearrangement or leukemia/lymphoma flow cytometry between 2016 and 2018.

Results Among 447 patients from the LGL-leukemia cohort, 24 (23 T- and 1 NK-cell) had a myopathy (7 non-specific inflammatory myopathy; 6 sIBM, 6 steroid-induced myopathy, 4 myopathy of indeterminate etiology, 1 critical-illness myopathy). Median time from LGL-leukemia diagnosis to sIBM onset was 7 years (range 6-8 years). Two of 6 sIBM patients received immunomodulatory therapy for LGL-leukemia when the myopathy manifested without improvement of weakness. Among 37 patients from sIBM cohort, 1 patient was diagnosed with T-cell LGL-leukemia and received immunomodulatory therapy for LGL without benefit. Combining both cohorts, only 7 patients had coexisting LGL and sIBM, 3/7 were anti-cN1A antibody-positive.

Conclusions A myopathy occurred in 5.3% of LGL-leukemia patients, and inflammatory myopathies, including sIBM, were the most common. The frequency of LGL-leukemia in our sIBM patients was only 16%, which is much less than previously reported. Although the association of LGL leukemia with autoimmune diseases is previously known, its co-occurrence with inflammatory myopathies warrants further investigation for potential therapeutic targets.

Authors/Disclosures
Pritikanta Paul, MD (University of California, San Francisco) PRESENTER	Dr. Paul has nothing to disclose.
Margherita Milone, MD, FAAN (Mayo Clinic)	Dr. Milone has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Argenx. Dr. Milone has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Neurology Genetics, AAN. The institution of Dr. Milone has received research support from Mayo Clinic, CCaTS-CBD. The institution of Dr. Milone has received research support from Mayo Clinic, SGP Award. The institution of Dr. Milone has received research support from MDA for Care Center grant. The institution of Dr. Milone has received research support from Regenerative medicine Minnesota.
	No disclosure on file
Mithun Shah	No disclosure on file
Teerin Liewluck, MD, FAAN (Department of Neurology, Mayo Clinic)	Dr. Liewluck has nothing to disclose.