Best Post of October 2019: Cytoplasmic Bodies in a Muscle Biopsy

The next in our "Best of the Month" series comes from October 7, 2019:

The inimitable Dr. Christian Davidson, formerly of Robert Wood Johnson Medical School at Rutgers and now at the University of Utah, sent in pictures of cytoplasmic bodies in a muscle biopsy from a patient with severe myositis. Thank you, Dr. Davidson!

Trichrome

Electron Microscopy

Cytoplasmic bodies in a muscle biopsy

The inimitable Dr. Christian Davidson, formerly of Robert Wood Johnson Medical School at Rutgers and now at the University of Utah, sent in pictures of cytoplasmic bodies in a muscle biopsy from a patient with severe myositis. Thank you, Dr. Davidson!

Trichrome

Electron Microscopy

Donahue does it again: a case of type 2 myotonic dystrophy from Providence, Rhode Island

A case from Dr. John Donahue, inimitable neuropathologist and neuropathology fellowship program director at Brown University:

"This is a fast myosin immunostain on a gluteus maximus biopsy from a 45-year-old woman who went on to have genetically-proven myotonic dystrophy, type 2 (DM2; proximal myotonic myopathy; PROMM).  The type 2 muscle fibers are EXTREMELY atrophic."

A Pattern-Based Approach to the Interpretation of Skeletal Muscle Biopsies

Chunyu (Hunter) Cai, MD, PhD

Chunyu (Hunter) Cai, Douglas Anthony, and Peter Pytel have authored a wonderfully useful review article in Modern Pathology entitled A Pattern-Based Approach to the Interpretation of Skeletal Muscle Biopsies. Dr. Cai wrote the following to me: "In this review, we take a pathology-friendly approach and categorize muscle biopsies into 6  morphologic groups, and discuss common differential diagnoses for each group. I think this review fills a void that there is not a good quick guide for NP fellows, residents and even neuropathologists who don’t sign out muscle cases on a routine base." Thanks, Drs. Cai, Anthony, and Pytel for a review article that will be a fixture on the desks of many neuropathologists in the coming years!

Guest Post from Dr. Mike Lawlor: Audentes Announces Positive Interim Data from First Dose Cohort of ASPIRO, a Phase 1/2 Clinical Trial of AT132 in Patients With X-Linked Myotubular Myopathy

Dr. Mike Lawlor

Regular contributor Mike Lawlor, MD, PhD passed this development along from the X-linked myotubular myopathy clinical research front:

Audentes Therapeutics has released an interim data update on the ASPIRO gene therapy clinical trial for X-linked myotubular myopathy.  In the 4^th quarter of 2017, three patients were given a single dose of an adeno-associated virus containing the human myotubularin gene.  To quote the press release:

"The early AT132 efficacy data observed in our first dose cohort of patients have exceeded our expectations," stated Dr. Suyash Prasad, Senior Vice President and Chief Medical Officer of Audentes. "At the 12-week timepoint, Patient 1 has improved from a severely compromised baseline to achieve a CHOP-INTEND score and maximal inspiratory pressure that are approaching the ranges normally seen in healthy children.  Importantly, Patient 1 has also attained several age-appropriate developmental milestones within this time period, including head-control, rolling over and sitting unassisted.  While still early in the trial, we view these initial efficacy data as a promising indicator of the potential for AT132 to bring meaningful benefit to patients and families living with this devastating disease."

On the safety side of things, Audentes reported a total of six adverse events (AEs) reported in ASPIRO, two of which were determined to be serious adverse events (SAEs). Per the press release, “Both SAEs occurred in Patient 3, the first of which was a hospitalization one week post-administration due to pneumonia and was deemed not treatment-related. Patient 3 was also hospitalized at week 7 post-administration due to a gastrointestinal infection and elevated troponin levels, the latter of which was deemed probably treatment-related and is responding to treatment with intravenous steroid administration and supportive care.”

On the pathology side of things, it will be a while before biopsies are evaluated or analyzed, as the trial design incorporated extensive strategies to keep the study pathologists blinded to timepoint, treatment group, and even whether a given sample belongs to a study patient.  Hopefully I’ll have the opportunity to share some of the pathology data at the 2019 AANP meeting.

The complete press release can be found at: http://investors.audentestx.com/phoenix.zhtml?c=254280&p=irol-newsArticle&ID=2324833

Audentes Therapeutics Announces Dosing of First Patient in ASPIRO, a Phase 1/2 Clinical Trial of AT132 for the Treatment of X-Linked Myotubular Myopathy

Following up on the last post, Dr. Mike Lawlor sent me this in an email:

"Audentes Therapeutics officially announced the dosing of the first patient for the X-linked myotubular myopathy treatment trial that we’ve been working on over the past few years.  We’ve been very involved in the translation from dogs to humans, and will be doing the human pathology work for the trial.  Here’s a link to that press release."

Lawlor featured in video about his work in myotubular myopathy

Michael Lawlor, MD, PhD

Medical College of Wisconsin is highlighting the work of our colleague Dr. Michael Lawlor in the area of gene therapy for myotubular myopathy. Check out this wonderful 4-minute video!

FDA approves first drug for spinal muscular atrophy

The U.S. Food and Drug Administration recently approved Spinraza (nusinersen), the first drug approved to treat children and adults with spinal muscular atrophy (SMA). The FDA granted this application fast track designation and priority review. The drug also received orphan drug designation, which provides incentives to assist and encourage the development of drugs for rare diseases.

Thanks to Dr. Nick Willard for alerting me to this development.

Dr. Mike Lawlor is recognized for making critical strides in treatment of myotubular myopathy

X-linked myotubular myopathy (XLMTM) is a severe and fatal congenital myopathy for which there is currently no treatment.  As part of an international group of scientists studying treatments for this disease, Dr. Mike Lawlor (the neuropathologist serving Children's Hospital of Wisconsin) was recently featured on Milwaukee's WTMJ 10 o'clock news for his part in the work.  The piece is quite touching. Mike conveys a sense of urgency in finding a cure for this disease because he has gotten to
know several children stricken with XLMTM, and even has pictures of many of the little tikes up on his office wall.  Mike has presented his work on XLMTM at the past several AANP meetings, including trials using myostatin inhibition, targeted enzyme replacement therapy, and gene therapy on animal models of this disease.  The work in this story relates to the gene therapy trial that was recently published in Science Translational Medicine (depicted on the left), for which Mike was the study pathologist. A photomicrograph from the article was even featured on the front page of that prestigious journal.  He is continuing to work on these treatment options in preparation for translation to human clinical trials that will occur over the next few years. Congratulations to Dr. Mike Lawlor for splendidly representing neuropathologists in both the lay media and academic press.

Dr. Mike Lawlor's Proposed Muscle Biopsy Checklist

Comments are encouraged!!!!

Clinical History

1.  Gender of patient:    __male ___female

2.  Age at presentation:  _ _ years _ _ months

3.  Age at biopsy: _ _ years _ _ months

4.  Symptoms at presentation (check all that apply):

 Weakness

 Hypotonia

 Muscle pain

 Cardiac disease

 Central nervous system disease

 Respiratory difficulties

 Contractures

 Failure to thrive

 Others (see item 8)

5.  Elevated creatine kinase:  Yes  No  Unknown _______ Patient Value _________(Normal Range)

6.  Familial Inheritance:____None      ___Autosomal Recessive     ____Autosomal Dominant     ____X-linked

7.  EMG Findings: ____Not known        ____Myopathic              ____Neuropathic

8.  Other symptoms, signs, and lab data: ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Muscle Biopsy Tissue Information

1.            Name of Muscle:___________________________________________________________________

2.            Size of tissue collected*:  ______  X  ______   X  ______ cm

3.            Date of tissue collection*:        __ __ / __ __ / __ __ __ __

                                                m  m     d   d     y   y   y   y

4.            Biopsy method:  Open         Needle

5.            Freezing or Fixation Used*?      Frozen:                   Amount: _____ mg     Not known

 Formalin-fixed:         Amount: _____ mg     Not known

 Paraffin-embedded: Amount: _____ mg     Not known      

 Epon-embedded:      Amount: _____ mg     Not known

Histological Findings in Muscle Biopsy or Autopsy specimens

1.       Which standard histochemical stains were used*? (choose all that apply)

 H and E                   Gomori trichrome      NADH         COX            SDH

 COX/SDH                PAS                        Oil Red O     ATPase 4.3  ATPase 4.6

 ATPase 9.4              Other, specify: __________________________________________________________________________________________________________________________________________________________________________________

2.       Which of the following diagnostic abnormalities were noted on histochemical stains (choose all that apply)*?

Fatty replacement                ___absent         ___mild             ___moderate                 ___severe

Endomysial fibrosis              ___absent         ___mild             ___moderate                 ___severe

Myofiber degeneration                      ___absent         ___mild             ___moderate                 ___severe

Necrosis                             ___absent         ___mild             ___moderate                 ___severe

Myophagocytosis                 ___absent         ___present in ____ fibers

Myofiber regeneration (Basophilic fibers)        ____absent       ___present in _____ fibers

Abnormalities of fiber type          ____absent       _____present

Specify*:      Type 1 predominance                       ______ % Type 1 fibers

 Type 2 predominance                 ______% Type 2 fibers

 Fiber type grouping (of both fiber types)

Hypertrophic fibers               ____absent       _____present in _____ fibers

Atrophy/Hypotrophy                   ____absent       _____present

Specify:       All fibers within the specimen          

 Subsets of fibers, leading to excessive variation in fiber size

Specify (choose all that apply):    Single fibers                         Groups of fibers      

                                     Type 1 fibers only     Type 2 fibers only

Perifascicular distribution

             Atrophic/hypotrophic fiber shape

 Angulated     Round    

Myopathy-associated pathological structures, specify:     

Central nuclei                _____absent      _____present

Specify estimated % of fibers (include eccentric nuclei): _____

            Internal nuclei                _____absent      _____present

Specify estimated % of fibers (if not quantified above): _____

Inclusion bodies             ____absent       ____present in _____ fibers

Rimmed vacuoles                      ____absent       ____present in _____ fibers

            Nemaline rods               ____absent       ____present

Specify:             Restricted to one fiber type, specify which: _____     

                                                 Nuclear rods present

Ragged red fibers                      ____absent       ____present in _____fibers

COX- negative fibers                  Estimated number ______

Strongly SDH-reactive blood vessels (SSV’s)                  _____absent      _____present

Central cores                 ____absent       ____present in _____ fibers

            Minicores                      ____absent       ____present in ____ fibers

            Core-like lesions            ____absent       ____present in ____ fibers

            Targetoid fibers              ____absent       ____present in ____ % of fibers

            Marked hypotrophy of type 1 fibers                      ____absent       ____present

Inflammation                 ___absent         ___mild             ___moderate                 ___severe

Specify:

 Distribution

 Perivascular

                               Evidence of vascular damage            Thrombi identified in blood vessels

                         Focal

 Diffuse

 Endomysial

 Perimysial

 Involving fascia

             Associated with myofiber damage

              Associated with non-necrotic myofiber

              Granulomas

                        Necrotizing   Non-necrotizing   Giant cells present    Foreign material present

             Inflammatory cells identified

                        Specify (choose all that apply):

                         Lymphocytes

                         Neutrophils

                         Macrophages

                         Eosinophils (as a prominent component)

                         Microorganisms identified, specify which: _________________________________________

Abnormal storage material

Specify:

                        Excessive glycogen                    ____absent      ____mild           ____severe

                        Excessive intracellular lipid         ____absent       ____mild           ____severe

Additional observations

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

3.       Which immunohistochemical stains were used? (choose all that apply)

 Myosin immunohistochemistry (for fast and slow fibers)         

 Dystrophin panel

            Specify:

                        Dystrophin (DYS1)         ____absent       ____reduced      ____normal

                        Dystrophin (DYS2)         ____absent       ____reduced      ____normal

                        Dystrophin (DYS3)         ____absent       ____reduced      ____normal

                        Dystrophin (BMD Hotspot)         ____absent       ____reduced      ____normal

                        Spectrin                                    ____absent       ____reduced      ____normal

                        Utrophin                                    ____absent       ____normal       ____increased

                       

 Other stains for limb-girdle or congenital muscular dystrophy

            Specify:           

                        Laminin a2/Merosin                   ____absent       ____reduced      ____normal

                        Alpha dystroglycan (VIA)            ____absent       ____reduced      ____normal

                        Alpha dystroglycan (IIH)             ____absent       ____reduced      ____normal

                        Beta dystroglycan                      ____absent       ____reduced      ____normal

                        Alpha sarcoglycan                     ____absent       ____reduced      ____normal

                        Beta sarcoglycan                       ____absent       ____reduced      ____normal                  

Delta sarcoglycan                      ____absent       ____reduced      ____normal

                        Gamma sarcoglycan                  ____absent       ____reduced      ____normal

Dysferlin                                   ____absent       ____reduced      ____normal                  

Emerin                                      ____absent       ____reduced      ____normal

                        Collagen VI                               ____absent       ____reduced      ____normal

                        Caveolin 3                                 ____absent       ____reduced      ____normal

                        Desmin                                     ____absent       ____reduced      ____normal

                        Integrin a7                                ____absent       ____reduced      ____normal

                        nNOS                                       ____absent       ____reduced      ____normal

                       

 Inflammatory myopathy panel

                        CD4                                         ____absent       ____present in ___ % of lymphocytes

                        CD8                                         ____absent       ____present in ___ % of lymphocytes

                        CD20                                        ____absent       ____present in ___ % of lymphocytes

                        CD45                                        ____absent       ____present in ____% of mononuclear cells        

CD68                                        ____absent       ____present in ____% of mononuclear cells        

C5b-9                                       ____absent       ____present on endomysial capillary walls

Major Histocompatability Complex          ____absent     ____sarcolemmal       ____diffuse

4.        Additional immunohistochemical/immunofluorescence assays performed: __________________________________________________________________________________

5.       Other abnormalities noted on immunohistochemistry:  __________________________________

Epon-Embedded Tissue/Electron Microscopy (Muscle Biopsy/Autopsy Specimens)

1.       Abnormalities seen on:             Light microscopy (Toluidine blue staining)       Electron microscopy

 Both – Light microscopy and Electron microscopy

2.       Abnormalities noted in:            Contractile apparatus

                                                 Sarcotubular organization

                                                 Mitochondria, specify (choose all that apply):

 Abnormal shape       

 Abnormal numbers

                                                                         Abnormal location   

                                                                         Abnormal architecture

3.       Describe any pathological inclusions noted:     N/A _________________________________________________________________________________________

_________________________________________________________________________________________

4.       Describe any abnormal storage material identified:       N/A _________________________________________________________________________________________

_________________________________________________________________________________________

Interpretation:

Comment: