Pigmentary Abnormalities

CHAPTER | 11 Pigmentary Abnormalities




image Lentigo

image Postinflammatory Hyperpigmentation

image Nasal Depigmentation (Dudley nose, snow nose)

image Vitiligo

image Canine Uveodermatologic Syndrome (Vogt-Koyanagi-Harada–like syndrome, VKH)


Lentigo



Features


Lentigo is an asymptomatic condition characterized by one (lentigo) or more (lentigines) flat macule(s) or patch(es) of black skin. It is common in dogs, with highest incidences reported in middle-aged to older dogs. It is uncommon in cats, with the highest incidence in young orange cats.



Dogs


In dogs, lentigo appears as one or more macular to patchy areas of hyperpigmented skin. Lesions are most commonly found on the ventral abdomen and chest.



Cats


In cats, multiple 1- to 10-mm-diameter black macules may coalesce on the lips, gingiva, pinnae, or eyelids.



Top Differential


Melanoma is the differential.



Diagnosis



1 History and clinical findings.

2 Dermatohistopathology: epidermal hyperplasia, hyperpigmentation, and increased numbers of melanocytes.


Treatment and Prognosis



1 No medical treatment is known.

2 The prognosis is good as lentigines are benign skin changes and a cosmetic problem only.

image

FIGURE 11-1 Lentigo.


Multiple pigmented macules on the lips of a young adult cat.


image

FIGURE 11-2 Lentigo.


Multiple pigmented macules on the ear pinna of a young adult cat.



Postinflammatory Hyperpigmentation



Features


In postinflammatory hyperpigmentation, skin (melanoderma) or hairs (melanotrichia) become hyperpigmented as a sequela to an underlying skin disease such as pyoderma, demodicosis, dermatophytosis, or hypersensitivity. This hyperpigmentation may be focal and circumscribed, patchy, or diffuse. It is common in dogs and uncommon in cats.



Top Differentials


Differentials include lentigo and melanoma.



Diagnosis



1 History, clinical findings, and identification of underlying diseases.


Treatment and Prognosis



1 The underlying cause should be identified and treated.

2 The prognosis is good. Melanoderma usually resolves slowly after the underlying cause has been treated. Melanotrichia usually resolves at the next shedding cycle.

image

FIGURE 11-3 Postinflammatory Hyperpigmentation.


Generalized hyperpigmentation associated with resolving erythema multiforme.


image

FIGURE 11-4 Postinflammatory Hyperpigmentation.


Multiple pigmented macules on the lateral flank of a dog. The initial papular dermatitis was caused by contact dermatitis associated with a medicated shampoo.



Nasal Depigmentation (Dudley nose, snow nose)



Features


Nasal depigmentation is an idiopathic disorder in which affected dogs are born with a pigmented nose, which later in life lightens to a light brown or whitish color. Nasal depigmentation may wax and wane, may be seasonal, may resolve spontaneously, or may be a permanent change. Only the nose is affected, and the normal cobble texture of the nose is preserved (autoimmune skin diseases destroy the normal architecture). It is common in dogs, with the highest incidence in Golden retrievers, yellow Labrador retrievers, Siberian huskies, and Alaskan malamutes.


Dudley nose usually describes a permanent pigmentary defect (undesirable show fault), whereas snow nose describes transient, seasonal depigmentation changes.

Related posts:

  1. Congenital Diseases
  2. Viral, Rickettsial, and Protozoal Skin Diseases
  3. Fungal Skin Diseases
  4. Avian and Exotic Animal Dermatology

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Sep 10, 2016 | Posted by in SMALL ANIMAL | Comments Off on Pigmentary Abnormalities

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