17 - 92 - POLYMORPHIC LIGHT ERUPTION Flashcards
most common photodermatosis, with a high prevalence, particularly among young women, in temperate climates
Polymorphic light eruption (PMLE)
areas spared in Polymorphic light eruption (PMLE)
face and hands
- presumably because of continuous natural hardening resulting from daily sun exposure
most common form of Polymorphic light eruption (PMLE)
The papular form, characterized by large or small separate or confluent erythematous and edematous papules that may form clusters, is most common
Diagnostic Criteria for Polymorphic Light Eruption
When is photoprovocation best perfomed
Photoprovocation is best performed before the beginning of the sunny summer season, preferentially in early spring, to avoid the false-negative results that may occur when the test is done too late in the season (ie, late spring or summer) because of tolerance induction through natural photohardening.
principles of photoprovocation
- 2 symmetrically located test areas at predilection sites, preferably on previously involved skin, are exposed daily for 4 to 5 days to increasing suberythemal or near-erythemal doses of UVA or UVB radiation (or solar-simulated UV radiation).
suggested pathophysiology of PMLE
resistance to ultraviolet (UV)-induced immune suppression with subsequent delayed-type hypersensitivity reaction against UV-induced antigen(s)
T or F. Sunburn is not mandatory for the development of a PMLE skin rash.
True
Most common primary lesion of PMLE
Papule
Most common UV radiation causing PMLE
UVA radiation (320 - 400 nm)
True about PMLE except:
a. PMLE is seen more frequently in temperate latitudes and rarely in equatorial latitudes
b. PMLE usually has its onset within the first 6 decades of life and affects females approximately 4 times more often than males.
c. PMLE patients with skin types I to IV, PMLE had the highest prevalence in individuals with skin type I.
d. PMLE is the most common photo dermatosis
B
Page 1611. Similar to many autoimmune disorders PMLE usually has its onset within the first 3 decades of life and affects females approximately 4 times more often than males.
True of PMLE except:
a. Once UV exposure ceases, all lesions of PMLE gradually resolve fully without scarring over several days, occasionally taking 7 to 10 days.
b. PMLE can also occur after recreational sunbed use.
c. Itching may be noted as the first sign of an impending PMLE eruption.
d. UVB (290 to 320 nm) usually seems more causative than UVA (320 to 400nm) at initiating PMLE.
D
UVA radiation (320 to 400 nm) usually seems more causative than UVB (290 to 320 nm) at initiating PMLE.
Mechanism of photohardening except
a. Melanization in the skin
b. Thinning of the stratum corneum
c. Restoration of immunologic susceptibility
d. None of the above
B
The mechanisms underlying the photohardening effect include melanization in the skin, thickening of the stratum corneum, and restoration of immunologic susceptibility, especially the impaired UVinduced Langerhans cells depletion, neutrophil infiltration, and neutrophil responsiveness to chemoattractants.
True of PMLE except
a. PMLE increases risk of skin cancer.
b. Genetic factors seem to play a role in PMLE, as a polygenic model indicated PMLE inheritance.
c. PMLE lesions may precede the development of lupus.
d. Within several hours to days, but usually not less than 30 minutes, after the first exposure to an intense dose of sunlight, usually in spring or early summer, itchy skin lesions of variable morphology appear on sun-exposed skin.
A
Together, this makes PMLE a potential skin cancer protective condition.
Areas spared by PMLE includes:
a. Face
b. Hands
c. Upper Chest
d. Extensor aspect of arms
e. Both A and B
E
In contrast, the face and the hands of patients with PMLE are typically spared, presumably because of continuous natural hardening resulting from daily sun exposure.
suggested pathogenesis of PMLE
resistance to ultraviolet (UV)-induced immune suppression (a physiologic phenomenon in healthy individuals) and a subsequent immune reaction to UV-modified elements in the skin are suggested
specific variant of PMLE linked to the African American population of the northern states of the United States (Michigan) and **dark-skinned individuals in Asia **(eg, Singapore, Taiwan, and India)
pinpoint papular variant
may be noted as the first sign of an impending PMLE eruption
itching
areas of predilection of PMLE
sun-exposed areas that are normally covered during winter such as the** upper chest and the extensor aspects of the arms are most affected**
variant of PMLE has been described in people with skin phototypes IV to VI, which is characterized by the development of very small papules on sun-exposed areas, including the face
pinpoint papular variant
localized subtype of PMLE which tends to affect boys in the spring and is characterized by pruritic papules and vesicles on their ear helices
juvenile spring eruption
to confirm PMLE, what test is performed?
photoprovocation
What is the result when PMLE is tested for their UVB-induced or UVA-induced minimal erythema dose?
Normal
- To confirm the diagnosis when the history and clinical features are not diagnostic, photoprovocation is performed in clinical practice to reproduce PMLE lesions, allowing also a subsequent skin biopsy.
