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Diagnostic Criteria for Myositis As a Facet of Chronic Gvhd
ASBMT Abstract Title
Diagnostic Criteria for Myositis as a Facet of chronic GVHD
Authors
Muhammad Mir, MBBS
Mrinal Patnaik, MBBS
Mark Litzow, MD
William Hogan, MB, B.Ch
Shahrukh Hashmi, MBBS
Affiliation
Division of Hematology, Blood & Marrow Transplantation
Mayo Clinic, Rochester, MN
Conflicts of Interest
None
Background: There is paucity of data on diagnostic criteria of Myositis/Muscle chronic Graft-versus-Host disease [cGVHD] due to rarity of the condition (<0.7% of all Allogeneic- Hematopoietic-Stem-Cell-Transplants [HSCT]. Myalgias are common after HSCT and confounding factors such as drugs (statins, steroids etc.), infections (muscle abscess) and tumor infiltration make diagnosis elusive. A diagnostic algorithm is lacking.
Methods: We retrospectively analyzed all allogeneic-HSCTs through the Mayo Clinic Database from Jan 1994-July 2013 to search for cases of myositis in association with cGVHD using terms “GVH”, “Muscle biopsy” and “Myositis”. Diagnostic criteria utilized were 1) Muscle Biopsy; 2) Elevated Enzymes: CK or Aldolase; 3) Serum Antibodies: ANA, anti-striated-muscle, Anti Ro/Jo/La, Sm, Scl-70, RNP 4) EMG and 5) Imaging: MRI or PET scan.
Results: Of 1058 screened allogeneic-HSCT, 68 were suspected clinically of having myositis, mostly presenting as focal or diffuse myalgias. 14 had muscle biopsies. 7 had confirmed myositis (Age 43-66 yrs., median 47). Median time to diagnosis was 19 months post-HSCT. All had cGVHD involving at least one other organ. 5/7 had AML and 6/7 received a fludarabine based conditioning. All biopsy positive and 2 biopsy indeterminate patients met at least 2 additional criteria besides biopsy (total criteria met ≥3). Of the 61 patients that were biopsy negative or not biopsied, none met 3 criteria (except 2 who could not be biopsied). 17 were tested but met none of the criteria (excluded). Remaining met ≤2 criteria not deemed sufficient for diagnosis. All biopsy proven patients received prednisone treatment. 5 received additional therapies including IVIG, ECP, Rituximab and Sirolimus.
Conclusions: Muscle biopsy, while confirmative, is invasive and is rarely pursued (20%). Only half of the biopsies were positive for myositis, likely due to patchy nature of the disease. All biopsy proven myositis patients met ≥3 criteria. Myositis as a component of cGVHD can be diagnosed using a composite of autoantibodies, muscle enzymes, EMG and imaging. This new criteria could be used to establish an algorithm in delineating the need for muscle biopsy for suspected myositis. (Fig 1 & Table 1)
No. of patients
|
Muscle Biopsy |
Enzymes+ |
Antibodies+ |
EMG+ |
MRI/PET+ |
7 |
Positive |
6/7 |
4/7 |
7/7 |
2/2 |
2 |
Equivocal |
2/2 |
0/2 |
1/1 |
1/1 |
5 |
Negative |
1/5 |
0/3 |
4/4 |
0/3 |
44 |
Not Done |
30/40 |
7/23 |
8/16 |
11/19 |
58* |
TOTAL |
39/54 |
11/35 |
20/28 |
14/25 |
Table -1 Workup panel results of suspected Myositis.* 10 excluded due to lack of testing from n=68.
Fig-1 Number of patients meeting Myositis criteria. 