Muscle biopsy
Biopsy a clinically weak muscle (MRC grade 4/5).
Biopsy is taken from the belly of the muscle, and it is important to avoid the region of the tendon.
Each specimen should be about 1-2 cm in length and 0.5 cm in width.
The specimen should be wrapped in slightly moist gauze and placed in separate labeled sterile containers until they reach the laboratory. It is important not to place the specimens in a container of saline else this will lead to artifact. Nor should the entire specimen be placed in fixative else the important histochemistry stains, protein/enzyme analysis, and mutation analysis cannot be performed.
Obtain at least two separate specimens as muscle disorders can be multifocal (e.g., inflammatory myopathies).
Freeze the specimen in isopentane cooled in liquid nitrogen. The frozen tissue is then sectioned and stained for routine histochemistry.
A separate piece of muscle is fixed in formalin or Bouin's fluid for paraffin sections.
Another piece of muscle is taken for ultrastructural examination by EM. This small piece of muscle tissue is secured on a clamp or stretched out by suturing the muscle over a tongue blade, in order to prevent hypercontraction artifact. The tissue is fixed in glutaraldehyde for plastic (resin) embedding for EM.
MUSCLE BIOPSY TISSUE SUBMISSION PROTOCOL
The muscle biopsy should be taken from the belly of a moderately affected muscle (avoid EMG and injection sites).
Ideally, the muscle biopsy is 2.5 – 3.0 cm length by 1.0 cm width for an adult or 2.0 cm length by 0.5 cm width for a child.
Divide the muscle into three portions:
a. 1.5 cm fresh (ideal) tissue portion on a saline-moistened Tefla gauze received on wet ice at refrigerator temperature.
b. 1.0 cm in 10% neutral buffered formalin (for Histology).
c. 0.5 cm in glutaraldehyde (for Electron Microscopy).
The fresh tissue, once received, will be frozen by MLabs. This specimen is most important for diagnosis as it is used for histochemical stains. If the muscle biopsy is from a child, omit the formalin fixed specimen and provide two fresh (or frozen) specimens along with the glutaraldehyde fixed specimen. Please complete the MLabs Muscle/Renal/Nerve Biopsy Requisition that is provided in the Muscle Biopsy collection kit and send the completed requisition back to MLabs along with the specimens. Specimen Handling Fresh tissue specimen is preferred provided that the specimen can arrive at MLabs within 4 hours of collection, Monday through Friday 7:00 am – 5:00 pm. Otherwise, the tissue must be frozen (see frozen instructions). FRESH TISSUE The first piece of muscle, 1.5 cm length by 1.0 cm width will be used for histochemical stains. Do not tease or pinch with forceps or let the tissue dry out. Wrap the tissue in a saline-moistened Telfa pad and place in a screw cap container. Do not immerse the tissue in saline. Container should be kept cold (wet ice) in transit; do not freeze. If the specimen cannot arrive at MLabs within 4 hours of collection, it must be frozen in the following manner: FROZEN TISSUE If liquid nitrogen is available: a. b. Isopentane method (PREFERRED): Add 50-100 mL of isopentane (2-methybutane) to a Nalgene or metal beaker. Suspend the beaker in a bath of liquid nitrogen and wait until the isopentane freezes to a white, chalky substance. Remove the beaker from the liquid nitrogen bath. Carefully drop or set the muscle on the frozen isopentane while keeping the muscle fibers straight and running in the same direction. Freeze the muscle for about 10 – 15 seconds. Place the frozen muscle in a Styroform container filled with 7 lbs of dry ice or in a -70ºC freezer. If isopentane is not available, roll the muscle gently in talc or glove powder, wrap it loosely in a piece of foil (do not flatten the muscle!), and immerse it into liquid nitrogen for 20 – 30 seconds. Place the frozen muscle in a Styrofoam container filled with 7 lbs of dry ice or in a -70ºC freezer until ready to ship. Avoid any thawing of specimen! If it thaws and re-freezes, the specimen may not be salvageable. Page 1 MLAB-OPS-xxxx-xxx1 2019-09-15MUSCLE BIOPSY TISSUE SUBMISSION PROTOCOL If liquid nitrogen is not available: roll the muscle gently in talc or glove powder, wrap it loosely in a piece of foil (do not flatten the muscle!) and place in a Styrofoam container filled with 7 lbs of dry ice. Avoid any thawing of specimen! FORMALIN FIXED TISSUE The second piece of muscle, approximately 1.0 cm length by 1.0 cm width will be used for paraffin sections. Stretch the muscle longitudinally on a piece of tongue blade using sutures tied at either end, then place specimen side down in a container with 10% neutral buffered formalin (NBF). If the muscle biopsy is from a CHILD, omit the formalin fixed specimen; instead provide two fresh (or frozen specimens) along with the glutaraldehyde fixed specimen. Specimen should be sent room temperature, do not freeze. GLUTARADLEHYDE FIXED TISSUE For the third piece of muscle tissue, 0.5 cm for electron microscopy, use a metal clamp or small piece of a sterile wooden tongue blade (size of a toothpick) to suture to a 3 mm thin portion of muscle in situ. Place this sample with the clamp or tongue blade attached in a vial containing 3% glutaraldehyde / 3% formaldehyde. Specimen should be sent at room temperature, do not freeze. Required Information and Shipping 1. 2. 3. 4. 5. Label the containers with the patient’s name and a 2nd patient identifier such as a date of birth or a medical record number. Complete the Renal/Muscle/Nerve Biopsy Patient Clinical Requisition and the MLabs Muscle/Nerve/Renal Requisition to accompany the specimens. The formalin and glutaraldehyde fixed specimens must be shipped in a room temperature container, separate from cold or frozen material. Care must be taken that these specimens do not freeze. Do not place these in the Styrofoam container with wet or dry ice. Once the formalin and glutaraldehyde specimens have been placed in their liquid containers and the tops secured, place inside the ziploc specimen biohazard bag with the absorbent sheet and seal. Wrap the bag with bubble wrap and place inside transport box. Please be careful to not contaminate the outside of the transport bags, paperwork or box when handling. Transport at room temperature. If shipping by UPS, place closed box inside Express Pak and seal according to instructions on the Express Pak. UPS, call 800.742.5877 to schedule pick up. Specimens should be sent Monday – Thursday (preferred); if sending on Friday is necessary, clearly indicate Saturday delivery required. Questions Call 800.862.7284 or you may visit mlabs.umich.edu
GENERAL MORPHOLOGIC FEATURES
Myofiber size: variable
Angulated fibers: present
Fiber groups: absent
Perifascicular atrophy: absent
Myofiber types (ATPase pH4.3, 4.6 and 9.4): Equal populations of both fiber
types; normal sized and atrophic fibers of both types
Blood vessels: normal
Amyloid (Congo red): absent
MYOPATHIC FEATURES
Necrotic fibers (Gomori trichrome, nonspecific esterase, CD68): present
De-/Regenerating fibers: present
Internal nuclei: present
Endomysial fibrosis (Masson Trichrome): mild
Fatty metaplasia: present
INFLAMMATION (CD3, CD20)
Perivascular: absent
Endomysial: absent
Vasculitis: absent
CYTOARCHITECTURAL FEATURES
Vacuoles (Gomori trichrome): absent
Target/Targetoid fibers (NADH-TR): absent
Small dark angulated fibers (NADH-TR): present
Lobulated Fibers (NADH-TR): absent
Cores (NADH-TR): absent
Minicores (NADH-TR): absent
Subsarcolemmal deposits: absent
Ragged Red Fibers (Gomori trichrome): absent
Nemaline Rods (Gomori trichrome): absent
Tubular Aggregates (Gomori trichrome): absent
COX-negative fibers (COX-SDH): within normal limits
Subsarcolemmal nuclear clusters: present
IMMUNOHISTOCHEMISTRY
MHC Class I (B1): Increased sarcolemmal staining in necrotic fibers
CD3 (A2): virtually absent
CD20 (A2): virtually absent
CD163 (A2): macrophages in endomysium and myophagocytosis
GROSS DESCRIPTION
A through C. Muscle, quadriceps, left, biopsy:
CONTAINER LABEL: Left quadriceps - fresh muscle biopsy for protocol.
RECEIVED: Unfixed on a saline soaked Telfa pad.
PIECES: 1. SIZE: 1.7 x 1.4 x 1 cm. PROCEDURE: (A) Sections are taken for
routine processing and paraffin-embedding; (B and C) samples are snap frozen
for histochemistry and placed in glutaraldehyde for possible electron
microscopy/Epon embedding; one piece is retained for frozen storage.
CASSETTES/PARTS: A1: Paraffin-embedded block; B1: Snap frozen block; C1-6:
Epon-embedded blocks, NS.
lmb/11/17/2023
Candi Bennett
MICROSCOPIC DESCRIPTION
STAINS
Paraffin sections (tissue block A1): Hematoxylin and eosin, Masson trichrome,
Congo red, CD163 (scavenger receptor cysteine-rich [SRCR] 1), CD3 (T cell
marker), CD20 (L26, B cell marker)
Cryosections (tissue block B1): Hematoxylin and eosin, Gomori trichrome,
alkaline phosphatase, nonspecific esterase, NADH-tetrazolium reductase,
succinate dehydrogenase, cytochrome oxidase-succinate dehydrogenase, ATPase
(pH4.3, 4.6 and 9.4), MHC Class I
Plastic-embedded sections (tissue blocks C1-6): Paragon
TISSUE QUALITY: Within normal limits
GENERAL MORPHOLOGIC FEATURES
Myofiber size: Mild variation
Angulated fibers: Rare
Fiber groups: Absent
Perifascicular atrophy: Absent
Myofiber types (ATPase pH4.3, 4.6 and 9.4): Equal populations of both fiber
types; normal sized and atrophic fibers of both types
Blood vessels: Within normal limits
Endomysium: Mild increase in collagen
Amyloid (Congo red): Absent, including sarcoplasmic compartment
MYOPATHIC FEATURES
Necrotic fibers (Gomori trichrome, nonspecific esterase, CD163): Present
(myophagocytosis)
De-/Regenerating fibers: Present
Internal nuclei: Present
Endomysial fibrosis (Masson trichrome): Mild
Fatty metaplasia: Mild
INFLAMMATION (CD3, CD20)
Perivascular: Sparse
Endomysial: Sparse
Vasculitis: None identified
CYTOARCHITECTURAL FEATURES
Red-rimmed vacuoles (Gomori trichrome): Absent
Vacuoles (H&E): Present (not a specific finding)
Target/Targetoid fibers (NADH-TR): Absent
Small dark angulated fibers (NADH-TR): Very rare
Lobulated Fibers (NADH-TR): Absent
Cores (NADH-TR): Absent
Minicores (NADH-TR): Absent
Subsarcolemmal deposits: Absent
Ragged Red Fibers (Gomori trichrome): Absent
Nemaline Rods (Gomori trichrome): Absent
Tubular Aggregates (Gomori trichrome): Absent
COX-negative fibers (COX-SDH): NOT increased
Subsarcolemmal nuclear clusters: Absent
Other: Not applicable
IMMUNOHISTOCHEMISTRY
MHC Class I (B1): Increased sarcolemmal labeling (patchy), labeling of
inflammatory cells and perimysium
CD3 (A1): Scattered peri- and endomysial T cells predominantly in a
perivascular distribution
CD20 (A1): NO significant B cell infiltrate is seen in this stain
CD163 (A1): highlights macrophages as part of the perivascular infiltrate and
foci of myophagocytosis
PARAGON-STAINED SECTIONS
NO further pathologic features are recognized in plastic-embedded and
Paragon-stained sections
Appropriate controls are reviewed and found satisfactory