Mitochondrial Pathology

MITOCHONDRIAL DISEASE PATHOLOGY

Syndromes
MELAS
Brain
Muscle
PEO
Autosomal Dominant
Sporadic
COX deficiency

Gomori trichrome stain

Muscle fibers have mild to moderate mitochondrial proliferation
(Red rim & speckled sarcoplasm)

Gomori trichrome stain

Marked mitochondrial proliferation. Mitochondria have replaced
most other structures in one of the muscle fibers

Increased SDH staining in muscle fibers with mitochondrial proliferation

Adult

Succinic dehydrogenase (SDH) stain

Child

Succinic dehydrogenase (SDH) stain Mitochondrial disorder	Succinic dehydrogenase (SDH) stain Normal
Muscle fibers with mitochondrial proliferation stain darkly for succinic dehydrogenase (SDH). SDH is the most sensitive stain for detecting mitochondrial proliferation.

Other stains H & E stain Muscle fibers with mitochondrial proliferation may have a clear external rim on H & E stain	Sudan stain Ragged red fibers often have increased lipid

Scattered COX- muscle fibers: Adult

Cytochrome oxidase (COX) stain

COX deficiency: Child

Cytochrome oxidase (COX) stain Mitochondrial disorder	Cytochrome oxidase (COX) stain Normal
Cytochrome oxidase (COX) levels are reduced in all muscle fibers (Left) Normal muscle (Right) has COX staining in all muscle fibers: More in type I than type II

Biopsy from muscle with normal strength

H & E stain Scattered intermediate sized polygonal muscle fibers
SDH stain	Cytochrome oxidase (COX) stain

Muscle fibers with excessive SDH staining (left) have reduced or absent COX (right) staining (arrows)

Biopsy from weak muscle

Gomori Trichrome stain Variable fiber size: Small fibers are rounded Increased endomysial connective tissue
SDH stain	Cytochrome oxidase (COX) stain

Muscle fibers with excessive SDH staining (left): COX is present in all fibers (right)