Proximal limb weakness and amyotrophy in a man with silicosis

Fraqueza muscular proximal e amiotrofia em um homem com silicose

A 55-year-old man presented with four-year history of progressive muscle wasting and weakness. His medical history disclosed advanced stage silicosis. The examination revealed flaccid quadriparesis with proximal amyotrophy. Serum creatine-kinase levels and screening for metabolic and inflammatory disorders were unremarkable. Muscle biopsy showed myopathic findings and the presence of abnormal amorphous and heterogeneous intracytoplasmic and subsarcolemmal content (Figure).

Figure
Chest CT-scan and muscle biopsy findings in silicosis. (A, B) Axial chest CT-scan showing bilateral severe advanced stage interstitial lung disease with marked lung architectural distortion (black arrow). Deltoid muscle biopsy showing abnormal subsarcolemmal and intracytoplasmic content disclosed in red in trichrome Gomori stain (C-E; white arrow) and black in NADH-TR histochemistry (F-H; white arrow-head).

Toxic myopathies can result from environmental and occupational exposure to toxic agents¹. Silicosis results from the deposition of crystalline silicon dioxide (silica) in lung and is associated with different systemic involvement, including osteoporosis, susceptibility to autoimmune disorders, constrictive pericarditis² and, rarely, myopathy.

References

• ¹
  Dalakas MC. Toxic and drug-induced myopathies. J Neurol Neurosurg Psychiatry. 2009;80(8):832-8. https://doi.org/10.1136/jnnp.2008.168294
  » https://doi.org/10.1136/jnnp.2008.168294
• ²
  Leung CC, Yu ITS, Chen W. Silicosis. Lancet. 2012;379(9830):2008-18. https://doi.org/10.1016/S0140-6736(12)60235-9
  » https://doi.org/10.1016/S0140-6736(12)60235-9

Publication Dates

• Publication in this collection
  Jan 2018

History

• Received
  15 Feb 2017
• Accepted
  04 Oct 2017