SPECIAL FEATURE- DECEMBER 2006

What is the Complete Muscle Profile?

Contributed by Nina Humphries and Dr. Diane Shelton
Comparative Neuromuscular Laboratory
University of California, San Diego
La Jolla, CA

 

Appropriately collected and processed muscle biopsies are critical to the diagnosis of a neuromuscular disease. Since the problem is in the muscles, it is only logical that muscles should be evaluated. As muscles are metabolically very active, evaluation of specific enzyme localization and storage products can be important to a diagnosis. Fiber typing is also critical for an accurate interpretation of the pathological changes. The complete muscle profile, performed on fresh frozen muscle biopsy sections, includes histological and histochemical stains and enzyme reactions that allow a full evaluation of muscle, necessary for an accurate diagnosis and prognosis of a neuromuscular disease.  

Information on how to take a muscle biopsy can be found in our June 2012 case of the month

MUSCLE BIOPSY INTERPRETATION: Features that require assessment for variation from normal

  • Fiber size (atrophy, hypertrophy, hypotrophy) and profile (polygonal, round, angular)
  • Fiber type proportions and distribution patterns (fiber type paucity/predominance; fiber type grouping)
  • Numbers and position of nuclei (peripheral vs random and central)
  • Myonecrosis and regeneration
  • Cellular infiltration
  • Connective and vascular tissue morphology
  • Intramuscular nerve morphology
  • Muscle fiber type selectivity or prevalence for the pathologic changes observed

HISTOLOGIC STAINING METHODS AND ENZYME REACTIONS IN THE COMPLETE MUSCLE PROFILE

HISTOLOGIC OR HISTOCHEMICAL STAIN HISTOLOGIC FEATURES OF STAINING METHODS AND INTERPRETIVE VALUES PROVIDED

Hematoxyoin and Eosin

 

General morpho/pathologic features of muscle fibers, connective tissue and blood vessels. Regenerating fibers stain basophilic, nuclei have prominent nucleoli

1
Gomori Modified Trichrome General morpho/pathologic features. Good stain for nucleoproteins and lipoproteins; nuclei and aggregates of mitochondria and sarcoplasmic reticulum stain brilliant red. Stain of choice for demonstration of nemaline rods and ragged red fibers. Excellent stain for evaluation of nerve fiber morphology.
11

NADH dehydrogenase

 

Stains mitochondria AND sarcoplasmic reticulum. Highlights mitochondrial rich (“red”) fatigue resistant fibers, angular atrophied fibers, pyknotic nuclear clumps, tubular aggregates and mitochondrial aggregates.
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Succinic Dehydrogenase (SDH, Upper) and Cytochrome C oxidase (COX, lower).  Mitochondrial specific stains. Note the COX negative fibers (unstained fibers) that are appropriately stained for SDH (upper) from a dog with a suspected mitochondrial myopathy.
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Myofibrillar ATPases (fiber typing)

Differentiates type 1 from type 2 fibers and type 2 fiber subtypes.
Provides information on proportions and distribution patterns of fiber types, and selectivity of disorder for fiber types.

1
Esterase

Stains neuromuscular junctions and lysosomal activity of fibers and macrophages. In the image, numerous motor-end plates stain red-brown.

 

1
Acid phosphatase Stains lysosomes of fibers and macrophages. Aids in differentiation of infiltrating cell types. Vivid in lysosomal storage disorders
1
Peroxidase Stains specific granules of eosinophils.
1
Alkaline phosphatase

Stains regenerating fibers and proliferative connective tissues (not useful in canine muscle, but good in horses, cats, and human muscle). 

1
Periodic acid-Schiff (PAS)

External (basal) lamina, glycogen, and myelin are PAS positive. Good for detection of glycogen storage disorders.

1
Oil red O

Stains triglyceride fats; good for staining intramyofiber lipid stores and detection of lipid storage disorders.

1

Protein A-Peroxidase

 

Immunohistochemical stain for Ig localization at neuromuscular junctions, within muscle striations (anti-strial antibody), muscle nuclei, and sarcolemmal staining in cases of polymyositis (shown at right)

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