Canis ISSN: 2398-2942

Reactive (systemic and cutaneous) histiocytosis

Contributor(s): Charlie Walker

Introduction

  • Systemic (SH) and cutaneous histocytosis (CH) are related conditions.
  • In the cutaneous form all lesions are confined to the skin, with the systemic form the skin and multiple internal organs are involved. The differentiation is purely one of clinical distribution.
  • This disease is a reactive inflammatory process and unlike malignant histiocytosis the cells themselves do not have the characteristics of malignancy. Many cases of systemic histiocytosis present with signs only of the cutaneous form.
  • It is not commonplace for every dog with cutaneous histiocytosis to develop systemic disease.

Pathogenesis

Etiology

  • A chronic reactive inflammatory process leading to a proliferation of tissue macrophages, inciting cause unknown.
  • A persistent antigenic stimulus is suggested by the inflammatory milieu.
  • The clinical course and response to immunosuppressive treatments suggests a dysregulation on the immune response.
  • In Bernese Mountain Dog polygenic predisposition is suggested as SH is often associated within families.

Specific

Pathophysiology

  • Proliferation of the activated, interstitial/dendritic cells (histiocytes/Langerhans cells).
  • Cells do not have signs of atypia.
  • Two forms:
    • Cutaneous.
    • Systemic.
  • Chronic inflammatory, so clinical signs depend on affected organs.

Timecourse

  • Usually months to years.
  • Spontaneous resolution possible.
  • Waxing and waning course common.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Palmeiro B S et al (2007) Cutaneous reactive histiocytosis in dogs: a retrospective evaluation of 32 cases. Vet Derm 18 (5), 332-340 PubMed.
  • Affolter V K & Moore P F (2000) Canine cutaneous and systemic histiocytosis - reactive histiocytosis of dermal dendritic cells. Am J Dermatopathol 22 (1), 40-48 PubMed.
  • Baines S J et al (2000) Cutaneous T cell lymphoma mimicking cutaneous histiocytosis - differentiation by flow cytometry. Vet Rec 147 (1), 11-16 PubMed.
  • Scherlie P H et al (1992) Ocular manifestation of systemic histiocytosis in a dog. JAVMA 201 (8), 1229-1232 PubMed.
  • Mays M B & Bergeron J A (1986) Cutaneous histiocytosis in dogs. J Am Vet Med Assoc 188 (4), 377-381 PubMed.
  • Moore P F (1984) Systemic histiocytosis of Bernese mountain dogs. Vet Pathol 21 (6), 554-563 PubMed.

Other sources of information

  • Gaugere E & Prelaud P (eds) (2008)A Practical Guide to Canine Dermatology.Kalianxis. ISBN 9782915758115.
  • Withrow S & Vail D (2007)Small Animal Clinical Oncology (4),Saunders Elsevier. ISBN 0721605583.
  • Bonagura J D (ed) (2000)Kirk's Current Veterinary Therapy XIII Small Animal Practice, Saunders. ISBN 0721655238.


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