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Unilateral Calf Enlargement

By Joshua Sonnen, MD

Jul 31, 2023

Focal myositis

Clinical History

  • 61-year-old man who presented with several month history of right calf enlargement.
  • Past medical history: TIA
  • Relevant medications: statin, ibuprofen
  • EMG: nondiagnostic
  • Exam:
    • Nonfocal
    • Strength normal; gait normal
    • Left calf 30% larger than right calf, nontender

What is the diagnosis?

A. Neurogenic hypertrophy

B. Marginal zone lymphoma

C. Eaton-Lambert syndrome

D. Focal myositis


Focal myositis, Unilateral Calf Enlargement


Answer: D. Focal myositis

Focal myositis

  • Uncommon
  • Presents as mass lesion in a single muscle/muscle group
  • Occurs in young adults
  • Self-limiting
  • Etiology is unknown
  • Histology mimics idiopathic inflammatory myopathy or dystrophy
    • Neurogenic changes are common


Reference(s) / additional reading:

  • Heffner RR Jr, Armbrustmacher VW, Earle KM. Focal myositis. Cancer. 1977 Jul;40(1):301-6.
  • Auerbach A, Fanburg-Smith JC, Wang G, Rushing EJ. Focal myositis: a clinicopathologic study of 115 cases of an intramuscular mass-like reactive process. Am J Surg Pathol. 2009 Jul;33(7):1016-24.



Quick note: This post is to be used for informational purposes only and does not constitute medical or health advice. Each person should consult their own doctor with respect to matters referenced. Arkana Laboratories assumes no liability for actions taken in reliance upon the information contained herein.