Neuromuscular

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Dysferlin Deficiency (LGMD 2B)

Differential diagnosis

Varied Degrees & Patterns of Pathology in same muscle

Myopathy, Mildly active
  Varied fiber size
  Immature fibers scattered

VvG stain
Severe pathology
  Pyknotic nuclear clumps
  Replacement of muscle by fat

VvG stain

Active Myopathy


H&E stain
Myopathic features
  Necrosis (Pale fibers)
  Regeneration (Basophilic, smaller fibers)
  Fiber size: Varied


Necrotic muscle fibers

Necrotic muscle fiber replaced by phagocytic cells

Congo red stain

Necrotic & Regenerating muscle fibers

Acid phosphatase stain

Irregular internal architecture

NADH stain


Alkaline phosphatase stain
Immature smaller muscle fibers
  Alkaline phosphatase positive cytoplasm (Above)
  Type 2C fibers (Intermediate staining; Below)

ATPase pH 4.3 stain

C5b-9 stain
C5b-9 Complement deposits
  Muscle fiber surface membranes: Irregular, Punctate
  Muscle fiber cytoplasm: Necrotic fiber

C5b-9 stain

ATPase pH 9.4 stain
Type 2 muscle fiber predominance
  Most fibers are dark stained with ATPase pH 9.4

Chronic Pathology


H&E stain
Small muscle fibers
  Rounded
  Often in Myopathic Groups
Larger muscle fibers
  Often hypertrophic
  Occasionally necrotic


NADH stain

Muscle fiber internal architecture
  Coarse staining in scattered muscle fibers
  Necrotic fiber shows only pale staining
  Pyknotic nuclear clumps: Very small, dark-stained muscle fibers


H&E stain

Varied muscle fiber size
  Pyknotic nuclear clumps: Some muscle fibers are very atrophic and composed mainly of nuclei

Late Pathology


H&E stain
Size changes
  Small muscle fibers: Rounded; Often in Myopathic Groups
  Larger muscle fibers: Often very hypertrophic
Muscle fiber splitting
Endomysial connective tissue: Increased

H&E stain
Pyknotic nuclear clumps

Amyloid (LGMD 2B): Commonly in vessel walls

Red-Green birefringent amyloid in vessel walls

Amyloid is occasionally deposited on a muscle fiber surface (Left)

Inflammation, Lymphocytic: Found in some biopsies

Perimysial inflammation
  Cells in connective tissue between fascicles
Perivascular inflammation
  Cells around intermediate-sized vessels

Dysferlin staining of muscle fibers

Normal:
  Dysferlin around muscle fibers
LGMD 2B:
  Absent dysferlin on muscle fiber surface

Dysferlin mutations: Ultrastructure

From: C Angelini
Sarcolemma: Focal lesion Sarcolemma: Focal projections

Subsarcolemmal region: Vacuoles Subsarcolemmal region: Disrupted internal architecture

Dysferlinopathy: Muscle CT

From: C Angelini
Leg MRI: Involvement of posterior-medial gastrocnemius

Thigh MRI: Involvement of posterior muscles

Return to Pathology Index
Return to LGMD 2B

12/27/2014