JPC SYSTEMIC PATHOLOGY

INTEGUMENT SYSTEM

August 2016

I-F01

 

Signalment (JPC 21474-5/6):  2-year-old dog 

HISTORY:  This dog from Florida had an expanding 3 cm circular indurated granuloma with numerous sinuses and fistulas in the skin over the right flank. 

HISTOPATHOLOGIC DESCRIPTION:  SLIDE A:  Haired skin:  Affecting up to 75% of the deep dermis and subcutis, extending into the panniculus and separating and surrounding skeletal myofibers are coalescing 0.5-2mm inflammatory nodules centered on faint negative images of fungal hyphae embedded in eosinophilic cellular and karyorrhectic debris (lytic necrosis).  Necrotic foci and fungal hyphae are surrounded by numerous epithelioid macrophages, lymphocytes, plasma cells, and few neutrophils, with occasional multinucleated giant cells (foreign body and Langhans' type), admixed with fibroblasts and scant fibrous connective tissue. Inflammation extends into the adjacent adipose tissue and skeletal muscle.  Remaining skeletal myocytes are often shrunken with fragmented hypereosinophilic sarcoplasm and nuclear pyknosis (necrosis), or pale, swollen and vacuolated (degeneration).  Multifocally, scattered macrophages contain brown, intracytoplasmic pigment (hemosiderin).  Diffusely, there is mild orthokeratotic hyperkeratosis. 

Slide B:  Gomori methenamine silver (GMS):  Within the pyogranulomas are many, argyrophilic hyphae and hyphal fragments.  Hyphae are occasionally septate, 4-15um in width with non-dichotomous branching and thin, non-parallel walls. 

MORPHOLOGIC DIAGNOSIS:  Haired skin: Dermatitis and panniculitis, nodular, granulomatous, multifocal and coalescing, marked, with numerous fungal hyphae, breed not specified, canine. 

ETIOLOGIC DIAGNOSIS:  Cutaneous zygomycosis 

GENERAL DISCUSSION:

  1. Order Mucorales:
    1. Systemic disease called “mucormycosis”
    2. Genera: Absidia, Mucor, Rhizopus, Rhizomucor, Mortierella
  2. Order Entomophthorales
    1. Subcutaneous disease called “entomophthoromycosis”
    2. Genera: Basidiobolus, Conidiobolus
    1. Rhinocerebral
    2. Cutaneous/subcutaneous (most frequently in horses) – Basidiobolus haptosporus (horse) & Conidiobolus coronatus (dogs) most common
    3. Systemic
      1. Pulmonary
      2. Gastrointestinal

 PATHOGENESIS: 

 TYPICAL CLINICAL FINDINGS: 

 TYPICAL GROSS FINDINGS: 

 TYPICAL LIGHT MICROSCOPIC FINDINGS: 

 ADDITIONAL DIAGNOSTIC TESTS: 

 DIFFERENTIAL DIAGNOSIS: 

Gross (cutaneous granulomas):

 Histopathologic:

 COMPARATIVE PATHOLOGY: 

 REFERENCES: 

  1. Ginn PE, Mansell JEKL, Rakich PM. Integumentary system. ln: Maxie MG,ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed. Philadelphia, PA: Elsevier Saunders. 2016:659-660.
  2. Foil C, Grooters A. Miscellaneous fungal infections. In: Green CE. Infectious Diseases of the Dog and Cat. 4th ed. Philadelphia, PA: WB Saunders Company; 1998:683-684.
  3. Gross TL, Ihrke PJ, Walder EJ, Affolter VK. Infectious nodular and diffuse granulomatous and Pyogranulomatous diseass of the dermis. In: Skin Diseases of the Dog and Cat Clinical and Histopathologic Diagnosis. 2nd ed. Ames, IA: Blackwell Science Ltd., 2005:303-309.
  4. Isidoro-Ayza M, Pérez L, Cabañes FJ, Castellà G, Andrés M, Vidal E, Domingo M. Central nervous system mucormycosis caused by Cunninghamella bertholletiae in a bottlenose dolphin (Tursiops truncatus). J Wildl Dis. 2014;50(3):634-8. doi: 10.7589/2013-10-284. Epub 2014 May 7.
  5. Madson DM, Loynachan AT, Kariyawasam S, Opriessnig T. Systemic Conidiobolus incongruusinfection and hypertrophic osteopathy in a white-tailed deer (Odocoileu virginianus). J Vet Diagn Invest. 2009;21:167-170.
  6. Naota M, Shimada A, Morita T, Kimura K, Ochiai K, Sano A. Granulomatous pericarditis associated with systemic mucormycosis in a finless porpoise (Neophocaena phocaenoides). J Comp Pathol. 2009;140:64-66.
  7. Ortega J, Uzal FA, Walker R, Kinde H, DIab SS Shahriar F Pamma R, Eigenheer A, Read DH. Zygomycotic lymphadenitis in slaughtered feedlot cattle. Vet Pathol. 2010;47:108-115.
  8. Quesada O, Rodriguez F, Herraez P, Seara D, Espinosa de los Monteros A. Mucor ramosissimus associated with feather loss in canaries (Serinus canarius). Avian Dis. 2007;51:643-645.
  9. Scott DW, Miller WH, Griffin CE. Muller & Kirk’s Small Animal Dermatology. 6th ed. Philadelphia, PA: WB Saunders Company; 2001:384-386.
  10. Sosa M, Gamble KC, Delaski K, Righton A. Clinical challenge: systemic Rhizopus microsporus infection with renal cavitation in a grey seal (Halichoerus grypus). J Zoo Wildl Med. 2013;44(4):1134-8.
  11. Ubiali DG, Cruz RA, De Paula DA, Silva MC, Mendonça FS, Dutra V, Nakazato L, Colodel EM, Pescador CA. Pathology of nasal infection caused by Conidiobolus lamprauges and Pythium insidiosum in sheep. J Comp Pathol. 2013;149(2-3):137-45.


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