C. Endogenous Types of Dermatitis
a.
Atopic dermatitis
-
Clinical patterns change with age
-
Face and extensor extremities in children
-
Antecubital and politeal fossae in adults
-
Acute, subacute and chronic
-
Exacerbations and remissions typical
-
Epidemiology
-
Present in 5 – 10% of population with sensitive skin;
asthmatics also
-
Prevalence up 2-3 times in past decades
-
10-30% of children, up to 40%
-
60% begin in 1st year, usually after 1st
month
-
30% start in next 4 years
-
1/3 resolve in childhood
-
Diagnostic Criteria
-
Eczema – look at the distribution of it
-
Pruritus
-
Typical age-specific localization
-
Atopic constitution – person may have a genetically
determined state of hypersensitivity to environmental
allergens such as wool (as what Dr. Schwartz experienced
when his uncle gave him a wool sweater as a gift)
-
Personal or family history of atopy
-
IgE-mediated allergic sensitization
b.
Seborrheic dermatitis
-
Characteristics
- White-yellow scales occurring on the scalp
- Accompanied by erythema and pruritis
- Other sites = eyebrows, cheeks, ears,
nasolabial fold
- Stress makes it worst
D. Papulosquamous Disorders
a.
Psoriasis vulgaris
(vulgaris
= common)
-distribution characteristic = scalp, elbows, knees,
intragluteal
-sharply demarcated red plaques with silver scale
-Koebner
phenomenon = when psoriasis goes into an area of trauma
-familial
-nail pits, distal onycholysis (separation of the nail
plate from the nail bed)
-subungal
hyperkeratosis
-arthritis = assymetrical oligoarthritis and arthritis
mutilans (person cannot use their hands at all; least
common type of arthritis)
-not
curable but controllable
b.
Pityriasis rosea
-common, acute and often seen in the healthy young
-herald patch (the initial patch that precedes the
spreading)
-generalized along lines of cleavage
-self-limited 6-9 week course
-proposed etiology = springtime viral exanthema (skin
eruption)
c.
Lichen planus
-Pinhead, shiny, polygonal purple papules
-may
have surface cross-hatching (zig-zag contour)
-seen on flexor wrists, inner thighs
-mucosal white patches (leukoplakia); can also be seen
in the genitalia
-drugs may induce a similar eruption
d.
Syphilis (secondary)
-great mimicker of pityriasis rosea
-Papulosquamous
rash
-patchy (moth-eaten) alopecia
-condylomata
lata
-scaling of palms
-positive serology for RPR and FTA
e.
Sarcoidosis
-a
great mimicker pityriasis rosea as with syphilis
-may
resemble benign adnexal tumors
-may
resemble papulosquamous disease
-naked granulomas in skin and viscera
-skin biopsy may spare need for lung biopsy
E.
Ichthyoses
= disorder of keratinization characterized by dry
scaling skin
a.
Common ichthyosis
-autosomal
dominant
-excessive dry scaly skin on arms
b.
Acquired ichthyosis
-common type later in life
-sign of systemic disease (i.e. lymphoma)
c.
Sex-linked ichthyosis
-carried
on X chromosome
-brownish yellow scaling
-rare forms include grotesque Harlequin type
F. Pellagra
-4
Ds: Dermatitis, Diarrhea, Dementia, Death
-photodermatitis
– sensitivity to certain wavelengths of light
-acute dermatitis resembling sunburn initially
-“butterfly” facial rash similar to lupus
-vesicles and bullae may be evident
-dry, scaly, and hyperkeratotic parchment-like skin with
a yellowish-brown hue
-niacin deficiency (vit. B3)
-secondary pellagra: Hartnup disease, carcinoid
-seen in alcoholics
-differential diagnosis: other photodermatitis
G. Pigmentary Skin Diseases
a.
Vitiligo
-milk white splattering of patches
-1 –
2% of the general population worldwide
-2
types = nonsegmental and segmental
-loss of melanocytes in skin and rarely retina (problems
in retina may appear in areas of injury)
-social concern for people with dark skin
b.
Oculocutaneous Albinism
-2
types that are common = tyrosinase positive and
tyrosinase negative
-eye
signs = nystagmus, reduced acquity
-type II has golden hair, pigmented birthmarks and is
common in the
Caribbean
-predisposed to sun-induced skin cancers
H. Allopecia Arreata
-sudden hair loss from scalp and elsewhere
-regular circular patch appear rapidly
-no
inflammation, scaling or scarring
-may
have nail pitting as seen in psoriasis
-may
have spontaneous regrowth in 2-6 months
-organ-specific autoimmune disease
-other autoimmune findings may be seen
a.
Alopecia totalis = complete loss of hair from scalp
b.
Alopecia universalis = complete loss of all body hair
I. Traction Allopecia
-common
-result of sustained pulling on the hair as with tightly
braided hair or guys wearing ponytails
-may
produce permanent hair loss
J. Muerckle's Lines
-double white lines of the fingernails
-reflects hypoalbuminemia
-may
also be seen with chemotherapy
-does not grow out with nail plate because it is not in
the nail plate
K. Rosacea
-extremely common
-vascular instability
à
easy blushing
-most frequent in women ages 20-40 years
-exacerbated by hot spicy food and alcohol
-central facial erythema, acneiform papules, rhinophyma
(hypertrophy of nose with follicular dilation) in men
-Sporotrichosis
and Lupus erythmatosus give similar presentations
Back to the Integumentary System
Index
|
