Inflammatory / infectious / autoimmune / systemic disorders

Author: Nat Pernick, M.D. (see Authors page)

Revised: 7 August 2018, last major update October 2013

Copyright: (c) 2002-2018, PathologyOutlines.com, Inc.

PubMed Search: Ear gout

Related Topics: Gout and gouty arthritis

Cite this page: Pernick, N. Gout. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/eargout.html. Accessed October 16th, 2018.
Definition / general
  • Primary gout (90%): idiopathic (85%) due to overproduction of uric acid or known enzyme defects (5%, partial hypoxanthine guanine phosphoribosyl transferase deficiency [HGPRT]); may have normal excretion
  • Secondary gout (10%): increased nucleic acid turnover due to leukemia / lymphoma, chronic renal disease, HGPRT deficiency
Xray description
  • No calcifications
  • Elevated urinary uric acid, leukocytosis, increased erythrocyte sedimentation rate
  • Gouty tophi (depositions of sodium urate) commonly deposit in helix of ear as painful, skin covered, firm nodules
Microscopic (histologic) description
  • Tophi are composed of needle shaped aggregates of urate crystals with surrounding foreign body giant cell reaction
  • Urate crystals dissolve with routine processing, so fix a smear of crystals in absolute alcohol or nonaqueous fixation
  • Under polarized light microscopy, they have a needle-like morphology and strong negative birefringence (J Int Adv Otol 2016;12:216)
Microscopic (histologic) images

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Needle shaped crystals

Differential diagnosis
  • Pseudogout: rhomboid or needle shaped, weak positive birefringence with polarized light, radiographic calcifications