Crystals in body fluids

This article deals with crystals in body fluids.

Crystals

Joint crystals

Types:

• Gout = needle-shaped, negatively birefringent, yellow when aligned.
• Pseudogout = rhomboid-shaped, positively birefringent, blue when aligned.

Notes:

• Pseudogout also known as CPPD = calcium pyrophosphate dehydrogenase.
• Memory device: ABC+ = aligned blue is calcium & cuboid - positively birefringent.

Urine crystals

Types - morphology:

• Envelope shape (calcium oxalate).
• Diamond shape (uric acid).
• Coffin-lid shape (struvite).
• Hexagonal shape (cysteine).

Notes:

• Memory devices:
  • Diamonds are see-through; ergo, uric acid stones not seen on KUB.
  • Calcium oxalate = envelope, uric acid = diamond.
• Uric acid crystals: usually dissolve in formalin... but do not dissolve in alcohol.
• Calcium oxalate crystals are seen in the context of ethylene glycol poisoning.

Diseases

Gout

General

• Classically big toe.

Gross/radiology

• Radiologically may mimic anconeus epitrochlearis muscle.

Microscopic

Features:

• Tophi (advanced)
  • Reactive granulomatous inflammation.
    • Surrounds fluffy (cotton candy-like) material.
  • Fibrotic synovium.
  • Aggregates of urate crystals.

Images:

• Gouty tophus - A. xray, B. Diff-Quick, C. Pap smear, D. polarized light, E. H&E (archivesofpathology.org).
• Gouty tophus - low mag. (WC).
• Gouty tophus - high mag. (WC).
• Gout - several images (upmc.edu).

Pseudogout

• AKA Calcium pyrophosphate dihydrate deposition disease, abbreviated CPPD.

General

• Classically found in the knee.

Microscopic

Features:

• Crystals with a rhomboid-shape.
  • Positively birefringent, blue when aligned.

Notes:

• Memory device: ABC+ = aligned blue is calcium & cuboid - positively birefringent.

Images:

• Pseudogout - intermed. mag. (WC).
• Pseudogout - high mag. (WC).

See also

• Cytopathology.
• Medical renal diseases.

External links

• Foreign body granulomas (granuloma.homestead.com).