Skin - Pigment

Image of pigment in the skin from a male B6C3F1 mouse in a chronic study
Pigment-accumulation of pigment-laden cells in the dermis in a male B6C3F1 mouse from a chronic study.
Figure 1 of 2
Image of pigment in the skin from a male B6C3F1 mouse in a chronic study
Pigment-accumulation of pigment-laden cells in the dermis in a male B6C3F1 mouse from a chronic study.
Figure 2 of 2
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comment:

The diagnosis of pigment in the skin is characterized by the accumulation of pigment-laden cells (melanocytes or macrophages) in the dermis or subcutis ( Figure 1image opens in a pop-up window and Figure 2image opens in a pop-up window ). Pigment occurs almost exclusively in dermal studies as part of the response to topical application of a test article. Hence, pigment is typically accompanied by other lesions, such as inflammation (usually chronic or chronic active) or fibrosis.

recommendation:

When warranted (based on the judgment of the pathologist), pigment should be documented and assigned a severity grade. If it is a minor component of inflammation, it need not be diagnosed separately but should be described in the narrative.

references:

Peckham JC, Heider K. 1999. Skin and subcutis. In: Pathology of the Mouse: Reference and Atlas (Maronpot RR, Boorman GA, Gaul BW, eds). Cache River Press, Vienna, IL, 555-612.
Abstract: http://www.cacheriverpress.com/books/pathmouse.htm