JPC SYSTEMIC PATHOLOGY

INTEGUMENTARY SYSTEM

August 2016

I-F03 (NP)

 

Signalment (JPC 1597220):  Young alligator. 

HISTORY:  This alligator died unexpectedly.  At necropsy, a necrotic skin lesion was present in the flank area in the region where the skin of the leg meets the abdominal skin. 

HISTOPATHOLOGIC DESCRIPTION:  Scaled skin:  Focally there is ulceration with replacement by abundant eosinophilic cellular and karyorrhectic debris (necrosis), large numbers of macrophages, fewer heterophils and lymphocytes, and colonies of 2 x 4 um bacilli.  The inflammatory infiltrate extends into the deep dermis.  The adjacent epidermis is moderately hyperplastic and keratinocytes are shrunken and hypereosinophilic with pyknotic nuclei (necrotic), or are swollen and rounded with clear cytoplasm (hydropic degeneration).  There is mild ortho- and parakeratotic hyperkeratosis.  

Scaled skin, periodic acid-Schiff (PAS) stain:  Within the epidermis and extending into the deep dermis, there are numerous PAS positive yeast and septate hyphae with parallel walls 3 to 5 um in diameter, acute angle, dichotomous branching and terminal bulbous swellings. 

MORPHOLOGIC DIAGNOSIS:  Scaled skin:  Dermatitis, necrotizing, subacute, focally extensive, moderate, with ulceration, superficial bacilli and many yeast and hyphae, etiology consistent with Aspergillus spp., alligator, reptile. 

ETIOLOGIC DIAGNOSIS:  Cutaneous aspergillosis 

CAUSE:  Aspergillus spp. 

GENERAL DISCUSSION:

  • Ubiquitous, saprophytic, spore-forming fungus
  • Opportunistic infection associated with immunosuppression, excessive exposure to fungus, or prolonged antibiotic or corticosteroid therapy
  • Reported in crocodilians under poor husbandry conditions or with poor adaptability to the stresses of captivity, poor diet, or overcrowding
  • Entry into skin through abrasions or other wounds
  • Aspergillus , Mucor spp., Rhizopus spp., Candida spp., Fusarium spp., and Trichophyton spp., have been isolated from cutaneous lesions in crocodilians
  • Cutaneous infection is generally rare among domestic animals
  •  PATHOGENESIS:

     TYPICAL CLINICAL FINDINGS:

     TYPICAL GROSS FINDINGS:  

     TYPICAL LIGHT MICROSCOPIC FINDINGS:

     ADDITIONAL DIAGNOSTIC TESTS: 

     DIFFERENTIAL DIAGNOSIS (for fungal hyphae in tissue):

     COMPARATIVE PATHOLOGY:

     REFERENCES:

    1. Day MJ, Peeters D, Clercx, C. Aspergillosis and penicilliosis. In: Greene CE, ed. Infectious Diseases of the Dog and Cat. 4th ed. St. Louis, MO: Elsevier Saunders; 2012:651-666.
    2. Foster, RA. Female reproductive system and mammary gland. In: Zachary JF, McGavin MD, eds. Pathologic Basis of Veterinary Disease. 5th ed. St. Louis, MO: Elsevier Mosby; 2012:1114.
    3. Gelberg HB. Alimentary system and the peritoneum, omentum, mesentery, and peritoneal cavity. In: Zachary JF, McGavin MD, eds. Pathologic Basis of Veterinary Disease. 5th ed. St. Louis, MO: Elsevier Mosby; 2012:344.
    4. Lopez, A. Respiratory system, mediastinum, and pleurae. In: Zachary JF, McGavin MD, eds. Pathologic Basis of Veterinary Disease. 5th ed. St. Louis, MO: Elsevier Mosby; 2012:477-478.
    5. Pare JA, Sigler, L, Rosenthal KL, et. al. Microbiology: Fungal and bacterial diseases of reptiles. In: Mader DR, ed. Reptile Medicine and Surgery. 2nd ed. St. Louis, MO: Saunders Elsevier; 2006:217-226.
    6. Zachary, JF. Mechanisms of microbial infections. In: Zachary JF, McGavin MD, eds. Pathologic Basis of Veterinary Disease. 5th ed. St. Louis, MO: Elsevier Mosby; 2012:235-236.
    7. Dantas AFM, de Olivera-Filho JC, do Carmo PMS, Garino F Jr, Portela RA, Riet-Correa F, Simoes SVD. Nasal and cutaneous aspergillosis in a goat. J Comp Path. 2014;150: 4-7.


    Click the slide to view.



    Click on image for diagnostic series.



    Back | Home | Contact Us | Links | Help |