JPC SYSTEMIC PATHOLOGY

INTEGUMENTARY SYSTEM

September 2016

I-F12

Signalment (JPC# 1960546):  Persian cat 

HISTORY:  This cat had a nodular skin mass. 

HISTOPATHOLOGIC DESCRIPTION:  Haired skin and subcutis:  Expanding the deep dermis and subcutis, extending to the deep border, and elevating the overlying epidermis are multiple focally extensive pyogranulomas composed of numerous epithelioid macrophages, surrounded by fewer degenerate neutrophils, lymphocytes, plasma cells, occasional multinucleated giant cells, centered on necrotic debris with multiple embedded, occasionally fragmented aggregates of densely packed, 5-10 um wide, septate fungal hyphae with thick, nonparallel walls, rare irregular non-dichotomous branching, and up to 25 um diameter bulbous swellings.  Hyphae are often surrounded by radiating, club-shaped amorphous eosinophilic material (Splendore-Hoeppli reaction).  Surrounding and separating pyogranulomas are numerous reactive fibroblasts, small caliber blood vessels, and loose fibrous connective tissue admixed with mild hemorrhage and edema (granulation tissue), progressing to more mature fibrous connective tissue (fibrosis).  Multifocally, infiltrating the superficial dermis are low numbers of periadnexal to perivascular lymphocytes, plasma cells and fewer macrophages.  There is diffuse mild epidermal and multifocal follicular orthokeratotic hyperkeratosis.

MORPHOLOGIC DIAGNOSIS:  Haired skin and subcutis:  Pyogranulomas (pseudomycetomas), multiple, with granulation tissue, fibrosis, and numerous fungal hyphae embedded in Splendore-Hoeppli material, Persian, feline.

ETIOLOGIC DIAGNOSIS:  Dermal and subcuticular dermatophytosis

CAUSE:  Microsporum canis

CONDITION:  Feline dermatophytic pseudomycetoma

GENERAL DISCUSSION:

PATHOGENESIS: 

TYPICAL CLINICAL FINDINGS: 

Pseudomycetoma:

Feline dermatophytosis:

TYPICAL GROSS FINDINGS: 

TYPICAL LIGHT MICROSCOPIC FINDINGS: 

ADDITIONAL DIAGNOSTIC TESTS: 

DIFFERENTIAL DIAGNOSIS: 

For histopathologic findings:

COMPARATIVE PATHOLOGY: 

Pseudomycetomas in other species:

References: 

  1. Mauldin EA, Peters-Kennedy J. Integumentary. In: Maxie MG ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol. 1. 6th Philadelphia, PA: Elsevier Saunders; 2016:649-653.
  2. Gross TL, Ihrke PJ, Walder EJ, Affolter VK. Skin Diseases of the Dog and Cat Clinical and Histopathologic Diagnosis. 2nd ed. Ames, IA: Blackwell Publishing Professional; 2005:272, 288-291, 302.
  3. Hargis AM, Ginn P. The integument. In: McGavin MD, Zachary JF eds. Pathologic Basis of Veterinary Disease. 5th ed. St. Louis, MO:Mosby Elsevier; 2012:1040
  4. Miller RI. Nodular granulomatous fungal skin diseases of cats in the United Kingdom: a retrospective review. Veterinary Dermatology. 2010;21:130-135.
  5. Scott DW, Miller WH. Equine Dermatology. 2nd St. Louis, MO:WB Saunders Co;2011:187-189.


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