A preliminary survey of the histopathological features of skin from the planum nasale and adjacent skin of dogs unaffected by dermatological or respiratory disease

Hutt, John H.C.; Dunn, Karen; Scase, Tim; Shipstone, Michael A.

doi:10.1111/vde.12238

Cited by 11 publications

(14 citation statements)

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“…In our article we stated that "samples contained variable numbers of melanophages and, less commonly, free melanin granules within the superficial dermis, consistent with pigmentary incontinence, generally in the absence of observable inflammation". 1 We stand by this statement but accept that our figure 4 does not provide a good illustration of what we describe.…”

Section: Pigmentary Incontinence In the Skin Of The Planum Nasale Fromentioning

confidence: 77%

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Pigmentary incontinence in the skin of the planum nasale from normal dogs

Hutt¹,

Dunn²,

Scase³

et al. 2016

Veterinary Dermatology

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Pigmentary incontinence in the skin of the planum nasale from normal dogs We thank Danny Scott and William Miller for their letter regarding our finding 1 of pigmentary incontinence in the skin from the planum nasale and adjacent skin of dogs unaffected by dermatological or respiratory disease. In their letter they challenge this finding and, in particular, cite figure 4 of that article as demonstrating dermal melanocytes rather than melanophages.In our article we stated that "samples contained variable numbers of melanophages and, less commonly, free melanin granules within the superficial dermis, consistent with pigmentary incontinence, generally in the absence of observable inflammation". 1 We stand by this statement but accept that our figure 4 does not provide a good illustration of what we describe.It is often difficult to photograph free melanin pigment given the need to adjust fine focus during observation to appreciate the amount of this finely granular and often dispersed material. Close examination of figure 4 shows small clumps of melanin that do not appear to be associated with cells and are likely, therefore, to be free melanin. We do not dispute that many of the cells visible in figure 4 may represent dermal melanocytes rather than melanophages, and that this figure was not the optimal one to have been published; however, the cases regularly contained cells we believe to be melanophages. Furthermore, we believe that the differentiating features between melanophages and melanocytes cited by Scott and Miller in their letter may be overly simplistic.Given that we hypothesize that this pigmentary incontinence may be the result of chronic low grade trauma to the nasal planum (the nose frequently being a dog's primary interface with the environment), rather than the result of lichenoid inflammation, the melanophages seen in these clinically normal noses -which exhibited minimal or no inflammation at the time of biopsy -are likely to be quiescent, rather than actively phagocytic, and may therefore differ in appearance when compared to macrophages in actively inflamed lesions such as discoid lupus erythematosus. Interestingly, a survey of nasal biopsies from five clinically normal young dogs also found pigment incontinence in all cases, only two of which showed mild inflammation, which echoes our findings here. 2 It has been stated that it is difficult to distinguish melanocytes and melanophages by simple inspection of routine stained sections, 3 and that the morphology of the two cell types can overlap. 4 Immunohistochemistry is therefore likely to be required to fully elucidate the true ratio of melanophages to melanocytes in this instance. This is an area worthy of further attention. It continues to be our intention to carry out additional studies using the samples we have obtained in order to further characterize, amongst other features, the cells present, and this should include differentiating melanocytes from melanophages. We note that Scott and Miller have had to go back more than half a century to...

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Section: Pigmentary Incontinence In the Skin Of The Planum Nasale Fromentioning

confidence: 77%

“…1 We stand by this statement but accept that our figure 4 does not provide a good illustration of what we describe.…”

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confidence: 84%

Pigmentary incontinence in the skin of the planum nasale from normal dogs

Hutt¹,

Dunn²,

Scase³

et al. 2016

Veterinary Dermatology

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“…There are few investigations related to the rhinarium or planum nasale, in general, and in dogs specifically. Hutt, Dunn, Scase, and Shipstone () investigated 25 dogs of various age, breed, and sex with light microscopy. There are no details about the epidermal pigmentation and without ultrastructural observations the situation reported here can easily escape notice.…”

Section: Discussionmentioning

confidence: 99%

A variation of pigmentation in the glabrous skin of dogs

Elofsson

Kröger

2018

Journal of Morphology

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The usual pigmentation pattern in mammalian skin consists of fixed melanocytes in the basal layer of the epidermis, supplying keratinocytes with melanosomes. We observed that the glabrous skin (rhinaria and footpads) of dogs deviates from this pattern. In dogs, melanocytes are found in both the dermis and epidermis. The epidermal melanocytes are situated in the intercellular spaces of the basal and spinous layers. They are characterized by a quantity of cytoplasm containing a centriole, also developing melanosomes, and in some cases annulate lamellae. There is a high frequency of closely apposed melanocytes in the epidermis. Melanosomes in different stages of formation are also abundant. The morphology of the glabrous skin of dogs suggests transport of melanocytes from the dermis into the epidermis and formation of melanosomes in the epidermis. A distributed and intense pigment formation may be necessary to achieve the black noses of many dog breeds and wild canids, as well as dark footpads despite heavy abrasion and rapid skin renewal.

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“…

We thank John Hutt et al 1 for their recent article concerning the histopathological features of skin from the nasal plane of dogs unaffected by dermatological or respiratory disease. They report that "pigmentary incontinence" appears to be common at this site.

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confidence: 99%

“…Melanocytes are characterized by round to oval nuclei, intracytoplasmic accumulation of melanin granules so dense as to obscure the cell nucleus, and dendritic processes ( Figure 2). The image purporting to illustrate pigmentary incontinence in the article by Hutt et al 1 (their figure 4) shows melanocytes.…”

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confidence: 99%