JPC SYSTEMIC PATHOLOGY

INTEGUMENT SYSTEM

August 2016

I-F06

Signalment (JPC # 3104239):  14-month-old Newfoundland dog

HISTORY:  None

HISTOPATHOLOGIC DESCRIPTION: SLIDE A:  Haired skin:  Multifocally expanding the dermis, separating and surrounding adnexal structures and extending into the markedly hyperplastic and hyperkeratotic epidermis, are multiple coalescing nodules composed of numerous epithelioid macrophages and neutrophils with fewer lymphocytes, plasma cells, and rare eosinophils, often surrounded by loosely arranged fibroblasts.  Within this infiltrate are many oval, 10-20 um in diameter, yeast with a 1 um distinct double-contoured cell wall and granular protoplasm, which occasionally exhibit broad-based budding.  The overlying epithelium is markedly hyperplastic with numerous anastomosing rete ridges, abundant basilar mitoses, moderate acanthosis, and a 500 um thick layer of orthokeratotic and parakeratotic hyperkeratosis.  The inflammatory nodules often separate the stratum spinosum from the stratum corneum (intraepidermal abscesses); there are also multifocal intracorneal pustules, composed of degenerate neutrophils and necrotic debris.  Multifocally, apocrine glands are ectatic and endothelium lining vessels is mildly hypertrophied (reactive).

Slide B (PAS):  Haired Skin:  Multifocally, there are PAS positive 10-20 um diameter oval yeasts with double contoured walls and broad based budding within the dermis and epidermis.

MORPHOLOGICAL DIAGNOSIS:  Haired Skin:  Dermatitis, pyogranulomatous, multifocal to coalescing, marked, with intraepidermal abscesses, epidermal hyperplasia, and yeast, etiology consistent with Blastomyces dermatitidis, Newfoundland, canine.

ETIOLOGIC DIAGNOSIS:  Cutaneous blastomycosis

CAUSE:  Blastomyces dermatitidis

CONDITION:  Blastomycosis

SYNONYMS:  Gilchrist’s disease, Chicago disease, North American blastomycosis

GENERAL DISCUSSION:

PATHOGENESIS:

 TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS: 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

References:

  1. Caswell JL, Williams KJ. Respiratory system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 2. 6th ed. Philadelphia, PA: Saunders Elsevier; 2016:580-582.
  2. Ferguson DC, Hoenig M. Endocrine System. In: Latimer ed. Duncan and Prasse’s Veterinary Laboratory Medicine Clinical Pathology. 5th ed. Ames, Iowa: Wiley-Blackwell; 2011:301.
  3. Gross TL, Ihrke PJ, Walder EJ, Affolter VK. Skin Diseases of the Dog and Cat. 2nd ed. Oxford, UK: Blackwell Science; 2005:291-295.
  4. Hargis AM, Ginn PE. The integument. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 5th ed. St. Louis, MO: Mosby Elsevier; 2012:1042.
  5. Hirsh DC, Biberstein EL. Agents of systemic mycosis. In: Hirsh DC, MacLachlan NJ, Walker RL, eds. Veterinary Microbiology. 2nd ed. Ames, IA: Blackwell Publishing; 2004: 292-294.
  6. Imai DM, McGreevey N, Anderson JL, Meece JK. Disseminated Blastomyces dermatitidis, genetic group 2, infection in an alpaca (Vicugna pacos). Journal Vet Diagn Invest.  2014; 26(3):442-447.
  7. Klein BS, Squires RA, Foyer Lloyd JK, Ruge DR, Legendre AM. Canine antibody response to Blastomyces dermatitidis WI-1 antigen. Am J Vet Res. 2000; 61:554-558.
  8. Legendre AM. Blastomycosis. In: Greene CE, ed. Infectious Diseases of the Dog and Cat. 4th ed. St. Louis, MO: Saunders Elsevier; 2006:606-614.
  9. McMichael MA, O’Brien M, Smith SA. Hypercoagulability in dogs with blastomycosis.  J Vet Intern Med.  2015;29:499-504.
  10. Nemecek JC, Wuethrich M, Klein BS. Global control of dimorphism and virulence in fungi. 2006; 312:583-588.
  11. Rakich PM, Latimer KS.   In: Latimer KS, ed. Ducan and Prasse’s Veterinary Laboratory Medicine Clinical Pathology. 5th ed. Ames, IA: Blackwell; 2011: 338.
  12. Rappleye CA, Goldman WE. Defining virulence genes in the dimorphic fungi. Annu Rev Microbiol. 2006; 60:281-303.


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