---

INFLAMMATION: Cellular Patterns

Lymphocytic   B-cell   Focal inflammation   Focal invasion of muscle fibers   IM-VAMP (IBM)   Lymphorrhages   Myositis Histiocytes   Granuloma   Muscle fiber necrosis   Pathology types Also see:   Inflammatory myopathy

Focal lymphocytic inflammation: Nongranulomatous
H&E	Esterase
Accumulation of lymphocytes with small dark nuclei (Left) Only a minority of cells are esterase positive (Right) Differential diagnosis Brachiocervical Inflammatory Myopathy: Pathology Dermatomyositis with Vascular pathology: Pathology Lymphorrhages Vasculitis: Pathology

---

Granulomas

Differential diagnosis  Myopathy   General Myopathy: Clinical Pathology   Giant cells   Muscle   Nerve     Endoneurial     Perivascular   Other: Tissue changes   Perimysium   Tuberculosis

Congo red stain Cells in granuloma   Central: Histiocytes   Periphery: Lymphocytes Esterase stain Cells in granuloma   Confluent esterase     staining CD68 stain Granulomas Cells stain for   Acid phosphatase   Esterase   CD68 antigen

---

Granulomas: Differential Diagnosis Neuropathies Sarcoidosis Leprosy Churg-Strauss angiitis Wegener's granulomatosis Lymphomatoid granulomatosis Angioimmunoblastic lymphadenopathy Myopathies Foreign bodies & Tuberculosis: Have associated region of necrosis Other: Granulomatous Disorders

H&E stain

---

Granulomas: Features   Focal cell collections     Histiocytic cells       Location: Central       Nuclei: Large       Cytoplasm: Prominent       Stain with         Acid phosphatase: Perinuclear         Esterase: Cytoplasm         Antibodies: CD68; CD4     Giant cells: Markers       Present         Lysozyme         α1-antichymotrypsin       Absent: Myoglobin     Lymphocytes       Location: Peripheral       Nuclei: Small; Dark       Cytoplasm: Little       Component: γδ T-cells   Humoral Factors: associated     TNF     IL8

H&E stain H&E stain

---

Histiocytic cells in Granuloma
  Features: Abundant cytoplasm; Large, pale nuclei
  Location: May occupy region of lost muscle fiber

Congo red stain

---

Granulomas: Locations & Staining Patterns

---

Granuloma location: May cross tissue borders

Congo red stain

Granuloma
  Location: Extend into both Endomysium & Perimysium
  Composed of clusters of Histiocytic cells: Have abundant cytoplasm & large nuclei
Also see: Granuloma in nerve extending into both Endoneurium & Perineurium

---

Granuloma location: Perimysial Granuloma

Congo red stain Granuloma contains   Large histiocytic cells: Have abundant cytoplasm & large nuclei   Giant cell

---

Gomori trichrome stain

---

Acid phosphatase stain

Acid phosphatase (Above): Stains perinuclear region of granuloma cells   This differs from the confluent staining in IMAM cell foci Esterase (Below) shows confluent staining of cells in granulomas

Esterase stain

---

Granulomatous Disease: Perimysium

H&E stain

---

Granuloma in perimysium Congo red

Acid phosphatase stain

---

Granulomatous Myopathy, Chronic

  Granulomas
    Endomysial
  Muscle fibers
    Varied size: Hypertrophy & Atrophy
    Internal nuclei

H&E stain

---

Granuloma location: Endomysial Granuloma

H & E stain Large cells in granuloma

Esterase stain Confluent staining of cells in granuloma

Acid phosphatase stain Perinuclear staining of most cells in granuloma

---

Granulomatous myopathy: Muscle fiber pathology

H&E stain

Invasion & Replacement of non-necrotic muscle fibers by histiocytic granuloma cells

H&E stain

Invasion & Replacement of non-necrotic muscle fibers by histiocytic granuloma cells
  Granuloma cells: Large & Stain with acid phosphatase
  Muscle fibers: Progressively invaded & replaced by granuloma cells (Arrows)

H&E stain

Gomori trichrome stain

---

Congo red stain

Acid phosphatase stain

Erosion of non-necrotic muscle fibers around & along their edges by Histiocytic granuloma cells

---

Congo red stain

Replacement of Muscle fibers by Histiocytic granuloma cells

Acid phosphatase stain

---

MHC expression by muscle fibers & granuloma cells

Control muscle: MHC expression only in vessels

Other immune features
Alkaline phosphatase staining of perimysium	CD4 staining of granuloma cells

---

Giant cells, Multinucleated

Frozen sections

Congo red

Giant cells, Multinucleated
  Size: Very large
  Nuclei: Several in one cell; Large
  Cytoplasm: May stain strongly for lysosomal markers

H&E stain

H&E stain

Congo red stain

---

Giant cells stain for acid phosphatase (Arrow)

Acid phosphatase stain

---

Fixed muscle sections

H&E stain

H&E stain

H&E stain

---

Granulomatous Myopathy: Connective tissue pathology, Epimysial & Perimysial

Acid phosphatase stain

H&E stain

Non-Granulomatous Histiocytic Cellularity
  Scattered cells in Perimysium

Acid phosphatase stain

Scattered cells in Perimysium MHC Class I stain

---

Granulomatous Disease: Nerve, Perivascular

VvG stain Axon loss: Myelinated axons   Varied within fascicles

Acid phosphatase stain Histiocytic perivascular cells

---

Granulomatous Vasculitis, Nerve

Location: Epineurium, Perivascular
Serum antibody: pANCA

H&E stain

Granulomatous (Histiocytic) cellularity: Surrounds vessel
Damaged vessel wall: Fibrinoid necrosis

---

Alkaline phosphatase stain

Connective tissue around granuloma: Alkaline phosphatase positive

---

H&E stain

Vessel: Fibrinoid Necrosis

---

Gomori trichrome stain

Vessel wall: Damaged structure
Cells around vessel
  Histiocytic: Large, Abundant cytoplasm
  Eosinophils: Scattered

Congo red stain

---

Acid phosphatase stain

Histiocytic cells around vessel: Acid phosphatase positive

Acid phosphatase stain

---

Toluidine blue stain Axon loss   Large & Small myelinated Regenerating clusters: Small, Few

Toluidine blue stain Cells in Vessel Walls   Size: Large   Nuclei: Large   Cytoplasm: Abundant

---

Granulomatous Disease, Nerve

Location: Endoneurium & Perineurium Granulomas: Endoneurial & Perineurial
  Clusters of large cells extending into perineurium & endoneurium
Granulomas: Endoneurial & Perineurial
  Clusters of large cells
    Cells have large nuclei & abundant cytoplasm
    Some cells contain lipid droplets

---

Granulomatous Changes: Tuberculosis (Cerebellum)

Regional changes
Necrotic tissue (Top Right)
Granulomatous pathology (Bottom Left)
  Multinucleated giant cells
  Histiocytic cells: Scattered

H&E stain

---

Granulomatous tissue
  Multinucleated giant cells
  Scattered histiocytes

H&E stain

---

Tuberculous bacilli
  Small, red-stained structures

Acid fast stain

---

Return to Inflammatory myopathies
Return to Neuromuscular Syndromes
Return to Neuromuscular Home Page


10/17/2023