Neuromuscular

Home, Search, Index, Links, Pathology, Molecules, Syndromes,
Muscle, NMJ, Nerve, Spinal, Ataxia, Antibody & Biopsy, Patient Info


FOCAL MUSCLE INVOLVEMENT

Bulbar
Focal enlargement
Focal fibrosing myopathy
Focal myositis
Hamstring
Quadriceps
Scapular winging

MRI: Fatty atrophy of Quadriceps


Quadriceps



Quadriceps atrophy
Inclusion body myositis

Quadriceps: Selective Weakness


Quadriceps: Atrophy with normal strength


Quadriceps: Strength selectively spared




Hamstring weakness



Scapular winging


Scapular winging

Finger Extension Weakness


Triceps (or Elbow Extension) Weakness


Adductors: Leg & Arm


FOCAL MYOSITIS 2

  • Epidemiology
    • Onset Age
      • Range: Childhood to 70's
      • Common: Adulthood; Most in 30's to 50's
    • Sex: Male = Female
    • Identical twins: 1 set both with disease
    • Local pain
  • Clinical features
    • Muscle mass
      • Solitary (Asymmetric)
      • Pain: 14% to 75%
      • Enlarging (Days to Months)
      • Size: 1 to 20 cm
      • Quality: Firm; Dense; Tender
    • Muscles involved
      • Leg: Quadriceps; Gastrocnemius
      • Also: Abdomen; Arm; Forearm; Neck 1; Paraspinous; Tongue; Perioral
      • May involve: Whole, or region, of one muscle or several adjacent muscles
    • No generalized weakness
    • No joint involvement
    • Natural history
      • Self limited course: Months; < 4 years
      • Eventual spontaneous regression
      • Recurrence 4: 1% to 18%; May occur in other muscles
      • Reported prior events: Campylobacter; Borrellia burgdorferi; BCG vaccination
    • Differential diagnosis: Nodular fasciitis; Sarcoma; Proliferative myositis
    • Treatment
      • Control pain & inflammation: Analgesics & NSAIDS
      • Corticosteroids: 0.75mg/day for 3 to 12 weeks
      • Physical therapy to reduce contracture
      • ? Surgery
  • Laboratory
    • Serum CK: Normal; If high, increased frequency of developing more diffuse involvement
    • EMG: Myopathy + Spontaneous activity in affected muscle
    • CT: Poorly defined enlargement; Fatty infiltration; No discrete mass
    • MRI: Muscle enlargement; Edema (High T2 signal; Low T1 signal); Circumscribed mass
    • Ultrasound: Normal orientation of muscle fibers
    • Systemic disease associations: Behcet (5%)
    • Muscle pathology
      • Perimysial connective tissue: Thickened
      • Myopathic changes: Varied muscle fiber size; Internal nuclei
      • Inflammation: T-cell predominant
    • HLA types: A2, B62, Cw3 & DQ3 common to small series of Japanese patients
  • Differential diagnosis
    • Benign tumors
      • Rhabdomyoma, Fibromatosis, Intramuscular lipoma
    • Malignant tumors
      • Not restricted to single muscle
      • Rhabdomyosarcoma, Liposarcoma, Leiomyosarcoma, Metastasis
      • Vascular intra-muscular tumor
      • Inflammatory myofibroblastic tumors
      • Lymphoma
    • Proliferative myositis
    • Myositis ossificans
Focal myositis MRI
From M. Al-Lozi
MRI: T2 weighted image
Focal myositis
Brachialis (Arrow)


RECURRENT FEVER WITH LOCALIZED MYOSITIS or FASCIITIS

  Tumor necrosis factor receptor superfamily, member 1A (TNFRSF1A) ; Chromosome 12p13.2; Dominant
Return to Neuromuscular home page
Return to Myopathy & NMJ Index


References

1. Muscle & Nerve 1999;22:769-771
2. Muscle & Nerve 2000;23:1569-1575, J Neurol Sci 2004;227:2125, Neuromuscular Disorders 2016; Online August
3. Arth Rheum 2002;46:2189-2194
4. Rheumatology 2002;41:1318-1322

9/13/2016