JPC SYSTEMIC PATHOLOGY

INTEGUMENTARY SYSTEM

September 2016

I-M22 (NP)

 

Signalment (JPC 21474-26):  Middle-aged, breed unspecified dog

HISTORY:  Skin biopsy from a dog that had become increasingly lethargic and had haircoat thinning and loss over the trunk.

HISTOPATHOLOGIC DESCRIPTION:  Haired skin: Diffusely, there is mild epidermal and infundibular orthokeratotic hyperkeratosis with melanin pigment in all layers of the epidermis (hyperpigmentation). Follicular infundibula within the superficial dermis are distended up to 0.2mm by concentric layers of keratin admixed with cellular debris and melanin, and lined by attenuated external root sheaths.  Remaining deeper hair follicles are shrunken (follicular atrophy) and have thickened external root sheaths, lack internal root sheaths and contain irregular lamellations brightly eosinophilic tricholemmal keratin (telogenization/flame follicles). Dermal collagen fibers are shrunken and separated by abundant clear space (edema).  Occasionally, arrector pili muscles have pale vacuolated sarcoplasm.  Multifocally, apocrine glands are mildly ectatic and lined by attenuated epithelium. 

MORPHOLOGIC DIAGNOSIS:  Haired skin:  Atrophy, follicular, diffuse, moderate, with follicular and epidermal orthokeratotic hyperkeratosis, and follicular ectasia, breed unspecified, canine

CONDITION:  Hypothyroidism

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS: 

 TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Ferguson DC, Hoenig M. Endocrine system. In: Latimer KS, ed. Veterinary Laboratory Medicine Clinical Pathology. 5th ed. Oxford, UK: Wiley-Blackwell; 2011:312-313
  2. Mauldin EA, Peters-Kennedy J. Integumentary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. 5th ed. Philadelphia, Pennsylvania: Elsevier; 2015:587-588
  3. Graham PA, Refsal KR, Nachreiner RF. Etiopathologic findings of canine hypothyroidism. Vet Clin North Small Anim Pract. 2007;37:617-630.
  4. Gross TL, Ihrke PJ, Walder EJ. Atrophic diseases of the adnexa. In: Gross TL, ed. Skin Diseases of the Dog and Cat. 2nd ed. Ames, IA: Blackwell Science; 2005:480-484
  5. Hargis AM, Ginn PE. The integument. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 5th ed. St. Louis, Missouri: Mosby; 2007:1060
  6. Miller WH, Griffin CE, Campbell KL. Muller and Kirk’s Small Animal Dermatology. 7th Philadelphia, PA: W.B. Saunders; 2013:502-514
  7. Muntener T, Schuepbach-Regula G, Frank L, Rufenacht S, Welle MM. Canine noninflammatory alopecia: A comprehensive evaluation of common and distinguishing histological characteristics; Vet Derm. 2012;23:206-224.
  8. Shiel RE, Brennan SF, Omodo-Eluk AJ, Mooney CT. Thyroid hormone concentrations in young, healthy, pretraining greyhounds. Vet Rec. 2007; 161:616-619.


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