Ear
External ear tumors - benign / nonneoplastic
Gout
Author: Nat Pernick, M.D.
Last author update: 1 October 2013
Last staff update: 16 May 2022
Copyright: 2002-2023, PathologyOutlines.com, Inc.
PubMed Search: Ear gout
Related Topics: Gout and gouty arthritis
Table of Contents
Definition / general | Xray description | Laboratory | Microscopic (histologic) description | Microscopic (histologic) images | Differential diagnosis | Additional referencesCite this page: Pernick N. Gout. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/eargout.html. Accessed June 3rd, 2023.
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
Laboratory
- 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
Images hosted on other servers:
Needle shaped crystals
Differential diagnosis
- Pseudogout:
- Rhomboid or needle shaped
- Weak positive birefringence with polarized light
- Radiographic calcifications
Additional references
