Gomori Modified Trichrome
Succinyl Dehydrogenase
NADH
Cytochrome Oxidase
PAS with Diastase
Oil-Red-O
Acid Phosphatase
Alkaline Phosphatase
Non-Specific Esterase
ATPase (pH 9.4 and 4.5)
Congo Red

Spectrin
Dystrophin (N-terminal, C-terminal, Rod-domain)
Alpha, beta, delta, and gamma- Sarcoglycans
Beta-Dystroglycan
Utrophin
Merosin
Merosin-M
Emerin
Caveolin-3
Dysferlin
Collagen IV, Collagen VI
Laminin beta-1
Lamin A/C

CD3
CD20
CD8
CD4
CD68
Ubiquitin
MHC-Class 1
C5b-9
Congo Red with polarization and fluorescence microscopy

Modified SDH/COX double stain
Myophosphorylase
Myoadenylate Deaminase
PAS on plastic-embedded muscle sample
Electron microscopy for abnormal mitochondria, excess glycogen and lipid

Interpretation of a muscle biopsy requires an adequately sized specimen that is well-preserved and accompanied by clinical documentation that explains the clinical setting and differential. Open excisional biopsy of a clinically affected, non-end-stage is recommended. We do not recommend needle core biopsies. Needle biopsy samples may be signed out as non-diagnostic by H&E  evaluation without further workup.

If a specific muscle is not dictated by the clinical presentation, the following muscles are preferred (in order of preference):

Quadriceps
Biceps
Deltoid

Biopsy of the calf muscle or a paraspinal muscle is only recommended under guidance by a neurologist or neuromuscular disorders specialist. These muscle groups show histologic changes at baseline and may not be diagnostic outside of certain clinical settings. Calf muscle biopsies may be helpful when accompanying a sural nerve biopsy for evaluation of vasculitis.

Minimum recommended specimen size:
1 cm x 0.5 cm x 0.5 cm

Preferred specimen size:
Up to 2 cm x 1 cm x 1 cm

Avoid end stage muscle.

Biopsies taken during acute rhabdomyolysis may not be diagnostic, due to myofiber injury overwhelming other underlying pathological processes.

Avoid sites of prior electromyography evaluation
No infiltration with local anesthetic.
No clamps or tying to tongue blade.
Do not freeze the specimen.

Preparation for shipment
Wrap specimen loosely in lightly saline-moistened gauze or Telfa.

Do not immerse the tissue in saline, this introduces irreversible artifact.
Place the wrapped specimen into dry container e.g. specimen cup, and seal tightly.
Surround container with abundant wet ice. Do not ship on dry ice. Ice packs are not recommended.
Pack in a Styrofoam container and ship via courier, cab, FedEx or air.

If the specimen cannot be delivered to OHSU by 4:00 pm on a business day, the procedure below can be followed. Please note - this is not the recommended treatment for optimal preservation of the specimen. Strong consideration should be given to rescheduling the biopsy to allow coordination between the sending facility and OHSU for prompt specimen delivery. Evaluation for metabolic and mitochondrial myopathy will be limited in specimens that are not received promptly at OHSU.

The specimen should be retained at the sending lab until the following OHSU workday. Specimens should be kept on lightly saline-moistened (not soaking) gauze, in a closed specimen container, in the refrigerator. If the following day is a Saturday or a holiday, then the specimen should be held (even over the weekend if necessary), until the next available OHSU workday. The next morning, OHSU should be contacted prior to shipping, and then the specimen shipped in the morning on moistened gauze, in a dry container, on wet ice, to Lab Central at OHSU.

Preferred length: 6 cm Avoid stretching or crushing nerve. Keeping the fresh nerve straight, place it on a narrow strip of filter paper, cut slightly longer than nerve. Immerse in 10% neutral buffered formalin (NBF). The nerve will adhere to the paper and this will maintain the orientation of the fibers. Exception: if the clinician is suspecting paraproteinemia-associated neuropathy, send two samples: one fresh or in transport medium for immunofluorescence and another fixed in 10% NBF for light and electron microscopy.  When we receive the nerve specimen, we will transfer a portion of the biopsy to glutaraldehyde.