JPC SYSTEMIC PATHOLOGY

INTEGUMENTARY SYSTEM

August 2016

I-F10

Signalment (JPC #4008764):  A Panamanian golden frog

HISTORY:  None

HISTOPATHOLOGIC DESCRIPTION:  Skin:  Multifocally, there is moderate epithelial hyperplasia, characterized by keratinocytes that are piling up to six layers thick with increased mitotic figures, acanthosis, and mild, multifocal orthokeratotic hyperkeratosis. Within the stratum corneum, including the hyperkeratotic debris, there are numerous round, 5-15 um diameter chytrid thalli, which have 1-2 um thick walls. All three forms of thalli are present and include the following:  multifocal zoosporangium contain multiple discrete basophilic 2-3 um zoospores and have an injection papillae that is oriented away from the epidermis; fewer multinucleate forms with finely granular basophilic cytoplasm, multiple nuclei, and internal septation; and rare uninucleate forms with homogenous basophilic cytoplasm and a single nucleus. Within the hyperkeratotic debris and stratum corneum there are numerous empty thalli outlined by a 2 um thick eosinophilic walls. The hyperkaratotic debris also contains some necrotic debris admixed with numerous 1x3 um coccobacilli. Multifocally within the dermis there are low numbers of lymphocytes and plasma cells.

MORPHOLOGIC DIAGNOSIS:  Skin:  Epidermal hyperplasia, multifocal, moderate, with hyperkeratosis, minimal subacute dermatitis, and numerous intracorneal thalli, etiology consistent with Batrachochytrium dendrobatidis, ornate horned frog (Ceratophrys ornata), amphibian.

ETIOLOGIC DIAGNOSIS:  Chytridiomycotic dermatitis

CAUSE:  Batrachochytrium dendrobatidis

CONDITION:  Chytridiomycosis

GENERAL DISCUSSION:

 PATHOGENESIS:

 TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

 ULTRASTRUCTURAL FINDINGS:

 ADDITIONAL DIAGNOSTIC TESTS:

 DIFFERENTIAL DIAGNOSIS:

 COMPARATIVE PATHOLOGY:

 REFERENCES:

  1. Bradley GA, Rosen PC, Sredl MJ, Jones TR, Longcore JE. Chytridiomycosis in native Arizona frogs. J Wild Dis. 2002;38(1):206-212.
  2. Churgin S, Raphael B, et al. Batrachochytrium dendobatidis in aquatic caecilians (Typhlonectes natans): a series of cases from two institutions. J Zoo Wildl Med. 2013;44:1002-1009.
  3. Daszak P, Berger L, Cunningham AA, Hyatt AD, Green ED, Speare R. Emerging infectious diseases and population declines. Emerg Infect Dis. 1999;5:735-746.
  4. Fites J, Ransey J, Holden W, et al. The invasive chytrid fungus of amphibians paralyzes lymphocyte responses. Science. 2013;342:366-369.
  5. Forzan MJ, Gunn H, Scott P. Chytridiomycosis in an aquarium collection of frogs: Diagnosis, treatment, and control.  J Zoo and Wildl Med. 2008;39(3):406-411.
  6. Martel A, Blooi M, et al. Wildlife disease: Recent introduction of a chytrid fungus endagers western palearctic salamanders. Science. 2014;346:630-631.
  7. McMahon T, Sears B, et al. Amphibians acquire resistance to live and dead fungus overcoming fungal immunosuppression. Nature. 2014;511:224-227.
  8. Mills G. Salamander plague on Britain’s doorstep. Vet Rec. 2015;176:88.
  9. Nichols DK, Lamirande EW, Pessier AP, Longcore JE. Experimental transmission of cutaneous chytridiomycosis in dendrobatid frogs. J Wild Dis. 2001:37:1-11.
  10. Pessier AP, Nichols DK, Longcore JE, Fuller MS. Cutaneous chytridiomycosis in poison dart frogs (Dendrobates ) and White's tree frogs (Litoria caerulea). J Vet Diagn Invest. 1999;11:194-199.
  11. Stice MJ, Briggs CJ. Immunization is ineffective at preventing infection and mortality due to the amphibian chytrid fungus Batrachochytrium dendrobatidis. J Wild Dis. 2010:46(1):70-77.
  12. Van Ells T, Stanton J, Strieby A, Daszak P, Hyatt AD, Brown C. Use of immunohistochemistry to diagnose chytridiomycosis in Dyeing poison dart frogs (Dendrobates tinctorius). J Wild Dis. 2003:39(3):742-745.
  13. Voyles J, Young S, Berger L, Campbell C, Voyles WF, Dinudom A, Cook D, Webb R, Alford R, Skerratt L, Speare R. Pathogenesis of chytridiomycosis, a cause of catastrophic amphibian decline. Science. 2009: 326:582-585.

 

 


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