Difference between revisions of "Endocrine effects on the skin - Pathology"
| Line 38: | Line 38: | ||
*[[Thyroid Gland - Pathology#Hypothyroidism|'''Hypothyroidism''']]: | *[[Thyroid Gland - Pathology#Hypothyroidism|'''Hypothyroidism''']]: | ||
**Grossly: endocrine alopecia mainly over trunk and neck | **Grossly: endocrine alopecia mainly over trunk and neck | ||
| − | **Microscopically: mucin within the dermis | + | **Microscopically: endocrine alopecia plus mucin within the dermis -> myxoedema (dermal thickening), acanthotic epidermal and follicular infundibular epithelium |
| + | **Secondary pyoderma is common | ||
*[[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'''). | ||
Revision as of 11:29, 29 October 2008
 |
This article has been peer reviewed but is awaiting expert review. If you would like to help with this, please see more information about expert reviewing. |
|
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
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.
The majority of hair follicles will be in this phase. The hair grows in length. - Catagen: Transition phase.
The dermal papilla is broken away and the follicle shrinks. - Telogen: Resting phase.
The hair doesn't grow but stays attached while the dermal papilla is resting.
After telogen the follicle re-enters anagen and the dermal papilla reattaches to the base of the follicle. If the old hair has not already epilated it will be pushed out by the new growing hair.
Pathogenesis
General skin changes (endocrine alopecia) seen with endocrine disease include:
- Hypotrichosis.
- Alopecia; usually bilaterally symmetric and non-pruritic.
- Remaining coat is dry and dull
- Pigment disturbance.
- Seborrhoea.
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.
- Often complicated by pyoderma or secondary seborrhea
Specific changes associated with disease
- Hypothyroidism:
- Grossly: endocrine alopecia mainly over trunk and neck
- Microscopically: endocrine alopecia plus mucin within the dermis -> myxoedema (dermal thickening), acanthotic epidermal and follicular infundibular epithelium
- Secondary pyoderma is common
- Hyperadrenocorticism: Calcinosis cutis and dermal thinning.
- GH deficiency: Decreased dermal elastin and catagen follicles (Flame follicles).