Bone marrow amyloid spherulites in a case of AL amyloidosis

Area of Science:

• Biochemistry
• Pathology
• Microscopy

Background:

• Amyloidogenic proteins typically form parallel β-pleated sheets.
• Amyloid fibrils can rarely form radially oriented globular structures known as spherulites.
• Amyloid spherulites exhibit a characteristic Maltese cross pattern under polarized light microscopy.

Observation:

• Amyloid spherulites have been previously identified in vitro and in specific organs like the liver and small intestine.
• In vivo formation of amyloid spherulites is uncommon, with senile plaques in Alzheimer's disease rarely exhibiting this morphology.
• This study documents, for the first time, the presence of amyloid spherulites in a bone marrow biopsy.

Findings:

• The bone marrow biopsy sample from an AL amyloidosis patient revealed the presence of amyloid spherulites.
• This observation confirms the in vivo formation of amyloid spherulites in a new anatomical site.
• The specific amyloidogenic protein responsible for spherulite formation in this AL amyloidosis case requires further investigation.

Implications:

• The clinical significance of amyloid spherulites remains largely undetermined.
• Documenting amyloid spherulites in bone marrow may offer new insights into AL amyloidosis pathogenesis.
• Further research is needed to understand the formation, clinical relevance, and diagnostic value of amyloid spherulites in various amyloidosis types.