JPC SYSTEMIC PATHOLOGY

INTEGUMENTARY SYSTEM

October 2016

I-N32 (NP)

 

Signalment (JPC # 3054993):  9-year-old male Dutch shepherd

HISTORY:  Swollen right rear fourth digit

HISTOPATHOLOGIC DESCRIPTION:   Haired skin, digit:  Expanding the deep dermis, compressing adnexa, and elevating the overlying moderately hyperplastic epidermis is a 5 X 2 mm cyst lined by a thick wall of squamous epithelium which undergoes gradual keratinization and contains deeply basophilic keratohyalin granules within the stratum granulosum and melanin pigments throughout all cell layers.  The cyst lumen is filled with laminations of keratin admixed with hemorrhage and cellular debris. The dermis adjacent to the cyst is thickened with increased fibrous tissue (fibrosis) along with a cellular infiltrate composed of numerous macrophages and neutrophils, few lymphocytes and plasma cells, free melanin pigment and clusters of melanomacrophages (pigmentary incontinence), and hemorrhage.  Surrounding the third phalanx are multifocal to coalescing foci of fibrosis surrounding the previously described cellular infiltrate along with eosinophilic cellular and karyorrhectic debris (necrosis) and abundant hemorrhage.  Along the phalanx there are rare areas of scalloped bone with increased numbers of osteoclasts within Howship’s lacunae (bone resorption) as well as foci of woven bone (bony remodeling).  The adjacent epidermis is moderately hyperplastic with prominent anastomosing rete ridges and parakeratotic hyperkeratosis.  Multifocally, hair follicles contain laminations and fragments of keratin and aprocrine glands are mildly ectatic.

MORPHOLOGIC DIAGNOSIS:  Haired skin, digit:  Nail bed epidermal inclusion cyst with pyogranulomatous dermatitis, hemorrhage and necrosis, Dutch shepherd, canine.

GENERAL DISCUSSION: 

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS: 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Gross TL, Ihrke PJ, Walder EJ, Affolter VK. Skin Diseases of the Dog and Cat: Clinical and Histopathologic Diagnosis. 2nd ed. Ames, IA: Blackwell Science; 2005: 695-696.
  2. Stern AW, Pieper J. Pathology in practice. Symmetric lupoid onychodystrophy of the claw bed epithelium; J Am Vet Med Assoc. 2015; 246(2):197-9.
  3. Wilcock BP, Njaa BL. Special senses. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 1.  6th ed. Philadelphia, PA: Elsevier Saunders; 2016: 500.
  4. Wobeser BK, Kidney BA, Powers SJ, Withrow SJ, Mayer MN, Spinato MT, Allen AL. Diagnosis and clinical outcomes associated with surgically amputated canine digits submitted to multiple veterinary diagnostic laboratories. Vet Pathol. 2007; 44: 355-361.


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