Sarcoid neuropathy

Area of Science:

• Neurology
• Immunology
• Pathology

Background:

• Sarcoidosis is a multisystem inflammatory disease.
• Polyneuropathy can be a neurological manifestation of sarcoidosis.
• The precise pathological mechanisms linking sarcoidosis to polyneuropathy require further elucidation.

Observation:

• A patient presented with subacute sensory and motor polyneuropathy.
• Nerve biopsy of the sural nerve revealed epineurial and endoneurial granulomas.
• Granulomas caused displacement and axonal degeneration of surrounding nerve fibers.

Findings:

• Ultrastructural and teased fiber analyses confirmed axonal atrophy and degeneration.
• Secondary demyelination was observed, consistent with axonal damage.
• Epithelioid cells within granulomas expressed HLA-DR antigen.
• The observed nerve damage pattern is distinct from non-specific inflammatory demyelination.

Implications:

• This case highlights granulomatous inflammation as a direct cause of polyneuropathy in sarcoidosis.
• Understanding the specific nerve pathology aids in diagnosing and managing sarcoidosis-associated neurological complications.
• The presence of HLA-DR suggests an active immune response within the nerve, potentially targetable for therapy.