title: Pigmented colloid milium associated with exogenous ochronosis in a farmer with long-term exposure to fertilizers.
abstract: BACKGROUND
  Colloid milium is a rare cutaneous deposition disorder characterized by translucent papules developing on sun-exposed regions such as the face, neck and dorsal aspects of the hands and back. Exogenous ochronosis is caused by the accumulation of homogentisic acid resulting from long-term application of certain topical agents. Histology is characterized by yellow-brown pigment deposits in the papillary dermis. Prolonged use of hydroquinone may result in the development of the pigmented form of colloid milium, sometimes in association with ochronosis.
  
  
  METHODS
  A 53-year-old man presented with a 3-year history of multiple slow spreading pigmented papules on the dorsa of his hands, nose and ears. The patient had a long history of exposure to sun and fertilizers with no history of using hydroquinone bleaching creams. A later biopsy revealed the diagnosis of pigmented colloid milium associated with exogenous ochronosis.
  
  
  CONCLUSIONS
  UV light damage and long contact with fertilizers may have a role in the development of pigmented colloid milium associated with exogenous ochronosis.
authors.affiliation: Autoimmune Bullous Diseases Research Centre, Department of Dermatology, Razi Hospital, Tehran University of Medical Sciences, Iran;
authors.forename: Maryam
authors.initials: M
authors.lastname: Akhyani
authors.affiliation: Autoimmune Bullous Diseases Research Centre, Department of Dermatology, Razi Hospital, Tehran University of Medical Sciences, Iran;
authors.forename: Parvaneh
authors.initials: P
authors.lastname: Hatami
authors.affiliation: Autoimmune Bullous Diseases Research Centre, Department of Dermatology, Razi Hospital, Tehran University of Medical Sciences, Iran;
authors.forename: Zahra
authors.initials: Z
authors.lastname: Yadegarfar
authors.affiliation: Department of Dermatopathology, Razi Hospital, Tehran University of Medical Sciences, Iran; ; Department of Pathology, Cancer Institute, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Ghanadan
keywords: hyperpigmentation; melasma; sun exposure