JPC SYSTEMIC PATHOLOGY

INTEGUMENT SYSTEM

December 2016

I-N31

 

Signalment (JPC# 3058415):  Age and breed unspecified dog

HISTORY:  None

HISTOPATHOLOGIC DESCRIPTION:  Digit:  Extending from the epidermis is an unencapsulated, moderately cellular neoplasm composed of polygonal cells arranged in broad anastomosing trabeculae with irregular scalloped borders that surround a central core of amorphous parakeratotic keratin.  The neoplasm expands into the subungual space and replaces the palmar aspect of P3.  Neoplastic cells have distinct cell borders and abundant amounts of eosinophilic cytoplasm.  Nuclei are irregularly round to oval and vesiculate with 1-2 prominent nucleoli.  The mitotic count averages <1/10 HPF.  Neoplastic cells primarily undergo orderly keratinization without a granular layer.  Multifocally neoplastic cells contain abundant intracytoplasmic clear space and marginated nuclei (intracellular edema).  Multifocally there is single cell necrosis characterized by cells with hypereosinophilic cytoplasm and pyknotic nuclei.  The neoplasm compresses the adjacent bone causing lysis and bony remodeling.  Surrounding the neoplasm is a rim of fibroblasts admixed with numerous small caliber blood vessels and fibrous connective tissue (granulation tissue and fibrosis), which are adjacent to spicules of immature bone lined by osteoblasts (woven bone).  Diffusely surrounding the neoplasm, admixed within the fibrous connective tissue, and separating, surrounding and replacing the adnexa (adenitis) overlying the neoplasm are moderate numbers of lymphocytes and plasma cells.  Multifocally at the edge of the central pore there are moderate numbers of neutrophils and numerous 1 to 2 um coccobacilli.

MORPHOLOGIC DIAGNOSIS:  Nailbed:  Subungual keratoacanthoma, breed unspecified, dog. 

SYNONYMS:  Nailbed keratoacanthoma

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS: 

ADDITIONAL DIAGNOSTIC TESTS: 

DIFFERENTIAL DIAGNOSIS:

Nailbed epithelial tumors:

COMPARATIVE PATHOLOGY:

References:

  1. Goldschmidt MH, Dunstan RW, Stannard AA, von Tscharner C, Walder EJ, Yager JA. WHO Histological Classification of Epithelial and Melanocytic Tumors of the Skin of Domestic Animals, 2nd Series, Vol. III. In:  Schulman FY, ed. Armed Forces Institute of Pathology, American Registry of Pathology, and The World Health Organization Collaborating Center, Washington, D.C.;1998:25, 62.
  2. Gross TL, Ihrke PJ, Walder EJ, Affolter VK. Epithelial neoplasms and other tumors. In: Gross TL, et al. Skin Diseases of the Dog and Cat. 2nd ed. Ames, IA: Blackwell Science; 2005:698-700.
  3. Meuten DJ. Tumors in Domestic Animals. 4th ed. Ames, IA: Iowa State Press; 2002:63.
  4. Wobeser BK, Kidney BA, Powers BE, et. al. Agreement among surgical pathologists evaluating routine histologic sections of digits amputated from cats and dogs. J Vet Diagn Invest 2007;19:439-443.
  5. Yoo CB, Kim DH, Lee AJ, Suh HJ, Yoo S, Sur JH, Eom KD. Canine nail bed keratoacanthoma diagnosed by immunohistochemical analysis. Can Vet J. 2015;56(11):1181-4.


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