Primary CNS Nonamyloidogenic Light Chain Deposition Disease: Case Report and Brief Review

Area of Science:

• Neurology
• Nephrology
• Pathology

Background:

• Light chain deposition disease (LCDD) is a rare systemic disorder characterized by the extracellular deposition of monoclonal immunoglobulin light chains.
• LCDD primarily affects the kidneys but can involve other organs, including the central nervous system (CNS).
• The true incidence of LCDD restricted to the CNS is largely unknown, with very few cases previously reported.

Observation:

• A 44-year-old man presented with progressive neurological deficits, including hypoesthesia and weakness.
• Brain biopsy revealed amorphous, Congo red-negative, amyloid-like deposits in the white matter and vessels.
• Deposits showed kappa light chain restriction by chromogenic in situ hybridization (CISH) and immunohistochemistry.

Findings:

• The patient was diagnosed with light chain deposition disease (LCDD) limited to the CNS.
• Systemic workups for myeloma and lymphoma were negative, suggesting a primary CNS manifestation.
• The observed deposits were amyloid-like but Congo red-negative, a characteristic feature of LCDD.

Implications:

• This case expands the understanding of rare CNS manifestations of light chain deposition disease (LCDD).
• Accurate diagnosis requires specialized techniques like CISH and immunohistochemistry to identify light chain restriction.
• Further research is needed to elucidate the pathogenesis and incidence of LCDD restricted to the CNS.