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Endocrine effects on the skin - Pathology (view source)
Revision as of 11:11, 29 October 2008
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The endocrine system typically has effects on the hair growth cycle so alopecia is a common finding. Many types of [[Skin Metabolic - Pathology|endocrine skin disease]] cause similar pathology.
The endocrine system typically has effects on the hair growth cycle so alopecia is a common finding. Many types of endocrine skin disease cause similar pathology.
Affects dogs more than any other species.
===The hair growth cycle===
===The hair growth cycle===
[[Image:Flame follicles.jpg|right|thumb|125px|<small><center>'''Flame Follicles'''. Courtesy of A. Jefferies</center></small>]]
<p>Hair follicles grow in repeated cycles in a mosiac pattern so that the whole hair coat isn't lost at one time.
<p>Hair follicles grow in repeated cycles in a mosiac pattern so that the whole hair coat isn't lost at one time.
*'''Anagen''': Growth phase.<br>The majority of hair follicles will be in this phase. The hair grows in length.
*'''Anagen''': Growth phase.<br>The majority of hair follicles will be in this phase. The hair grows in length.
<p>Histologically many of the follicles will be in telogen where the haircoat is easily epilated and then fails to regrow. This is why alopecia occurs over areas of friction (trunk face etc) while the legs and tail are spared. Follicular and epidermal atrophy may be evident along with atrophy of the adnexa E.g sebaceous atrophy.</p>
<p>Histologically many of the follicles will be in telogen where the haircoat is easily epilated and then fails to regrow. This is why alopecia occurs over areas of friction (trunk face etc) while the legs and tail are spared. Follicular and epidermal atrophy may be evident along with atrophy of the adnexa E.g sebaceous atrophy.</p>
Specific changes associated with disease:
*Often complicated by pyoderma or secondary seborrhea
===Specific changes associated with disease===
*[[Thyroid Gland - Pathology#Hypothyroidism|'''Hypothyroidism''']]: Mucin within the dermis; myxoedema.
*[[Thyroid Gland - Pathology#Hypothyroidism|'''Hypothyroidism''']]: Mucin within the dermis; myxoedema.
*[[Adrenal Glands - Pathology#Adrenal_Hyperfunction|'''Hyperadrenocorticism''']]: [[Adrenal Glands - Pathology#Pathophysiology_2|Calcinosis cutis]] and dermal thinning.
*[[Adrenal Glands - Pathology#Adrenal_Hyperfunction|'''Hyperadrenocorticism''']]: [[Adrenal Glands - Pathology#Pathophysiology_2|Calcinosis cutis]] and dermal thinning.
*[[Pituitary Gland - Pathology#Pituitary_Hypofunction|'''GH deficiency''']]: Decreased dermal elastin and catagen follicles ('''Flame follicles''').
*[[Pituitary Gland - Pathology#Pituitary_Hypofunction|'''GH deficiency''']]: Decreased dermal elastin and catagen follicles ('''Flame follicles''').