Charcot-Leyden crystals

Charcot-Leyden crystal

From time to time the MicroGnome fields questions about the significance of Charcot-Leyden crystals seen in clinical specimens. Their name makes them sound a bit exotic and brings back vague recollections of small-print items from undergraduate lectures. Here are some useful pointers for the busy physician.


Named after Jean-Martin Charcot (observed in 1853) and Ernst Leyden (1872), these are rhomboid crystals (hexagonal, bipyramidal) of lysophospholipase that measure  up to 50 μm in length. They are produced by eosinophils.

Clinical significance

Charcot-Leyden crystals indicate an eosinophil response and are usually associated with allergic or parasitic diseases. These crystals can be seen in trichrome-stained preparations of faeces examined for enteric parasites, in respiratory secretions or more rarely in tissue biopsies. These crystals do not always signify parasite infection, and they may be present without blood eosinophilia.

Conditions associated with Charcot-Leyden crystal formation include:

  • gastrointestinal parasite infections
  • allergic diseases
  • (rarely) haematological and neoplastic conditions

Further reading (available on-line):

MicroGnome, 26th February 2011

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