Skin nontumor
Dermal collagen and elastic tissue alterations, and cutaneous deposits

Topic Completed: 1 August 2011

Minor changes: 5 August 2020

Copyright: 2002-2020,, Inc.

PubMed Search: Ochronosis

Mowafak Hamodat, M.B.Ch.B., M.Sc.
Page views in 2019: 2,178
Page views in 2020 to date: 1,969
Cite this page: Hamodat M. Ochronosis. website. Accessed October 21st, 2020.
Clinical features
  • Autosomal recessive disorder of increased urinary excretion of homogentisic acid (alkaptonuria), with deposition of ochre colored pigment in collagen rich regions (ochre: moderate orange-yellow)
  • Occurs in 50% with alkaptonuria
  • Due to disorder of homogentisic acid oxidase gene on #3q, intermediate component in metabolism of tyrosine and phenylalanine, causing accumulation of benzoquinone acetic acid, which binds to collagen irreversibly
  • Clinically black pigmentation of joints (arthritis with pigment deposition in cartilage and intervertebral disks), cardiovascular system (valvular calcifications and stenosis), kidney (black urine, pigmented stones) and skin (cutaneous pigmentation)
  • Also involvement of sclera of eye
Case reports
Microscopic (histologic) description
  • Yellow-brown sharply defined irregularly shaped and frequently fragmented fibers in superficial dermis
  • Ochronotic pigment is autofluorescent, appears black with methylene blue but does not stain with Van Gieson or Pearl stain or the Masson Fontana reaction
  • Pigment granules often present in epithelium and basement membrane of sweat glands, in endothelium and within dermal macrophages
  • Hydroquinone induced ochronosis shows melanophages in upper dermis associated with depigmentaion of the epidermal melanocytes
  • In early lesions, collagen fibers appear basophilic and swollen before developing characterstic yellow ochronotic morphology
  • With chronicity, large amorphous eosinophilic granules may develop resembling colloid milium
  • Solar elastosis and foregn body granuloma are common features
  • Pigmentation secondary to antimalarial drugs is due to melanin and hemosiderin deposition in addition to the classic ochronotic fibers
Additional references
Back to top
Image 01 Image 02