solar elastosis refers to histopathologic changes in degenerative dermal elastic tissue that occurs in photodamaged skin .
the predominant histological feature of solar elastosis is basophilic degeneration of elastotic fibers in the dermis , separated from the epidermis by a narrow band of normal - appearing collagen ( grenz zone ) with collagen fibers arranged horizontally .
the degree of elastosis correlates with the cumulative amount of ultraviolet radiation to which the skin has been exposed .
these are distinguished by a combination of anatomic location , clinical appearance , and histopathologic findings .
otherwise , the other clinical patterns which are histologically similar are usually grouped together under the term  solar elastosis . solar elastotic syndromes include solar elastosis , favre - racouchot syndrome , elastotic nodules of the ears , collagenous and elastotic plaques of the hands and colloid milia [ 4 , 5 , 6 , 7 , 8 , 9 , 10 ] . here
we present two patients with a rare clinical presentation of solar elastosis in the papular form .
a 55-year - old chinese man was referred to our clinic for regular screening for skin cancer . he had a history of diabetes mellitus , hypertension and had received a kidney transplant more than 10 years ago .
physical examination revealed three similar pearly telangiectatic red - brown firm papules on the nose and right nasal philtrum ( fig .
the lesions were asymptomatic and had been present for 2 months . a 3-mm punch biopsy of a representative lesion was performed .
histological evaluation of the skin showed marked solar elastosis with non - specific patchy chronic lymphoplasmacytic infiltrate ( fig .
2 ) . there was no evidence of malignancy on examination of multiple sections of tissue .
a 75-year - old chinese man , on regular follow - up for psoriasis , presented with a 1-month history of a bump on the face which bled a little with scratching .
moreover , he had a history of ischemic heart disease , hypertension , hyperlipidemia , diabetes mellitus and hypoadrenalism secondary to exogenous steroid use in the past .
physical examination revealed a 3-mm skin - colored papule on the left philtrum ( fig .
there was mild epidermal acanthosis with no evidence of tumor on examination of multiple tissue sections .
it appears to be uncommon for solar elastosis to manifest in a papular form and very often , it can resemble other skin disorders .
some of the mimics of papular solar elastosis include basal cell carcinoma , sebaceous hyperplasia , molluscum contagiosum and actinic keratosis .
he described the skin lesions as asymptomatic , shiny , smooth , firm papules , 110 mm in diameter , that can be multiple or solitary , with various colorations .
he reported two cases of papular elastosis and since then there has been no other literature found with regards to this unique presentation of solar elastosis .
it presents as thick , dry , coarsely wrinkled skin with loss of skin tone .
one of the most well recognized clinical variant is cutis rhomboidalis nuchae , in which there is thickened yellow leathery - appearing skin at the posterolateral aspect of the neck .
the origin of the elastotic material in the dermis has been postulated to be due to degradation of collagen and/or elastic fibers , overactive sun - damaged fibroblast synthesizing new elastic tissue , and an abnormal synthetic and degradative process . in favre - rachouchot syndrome , thickened yellow plaques with follicular cysts surrounded by multiple open comedones are typical .
the skin around the eyes is a usual site , and the condition occurs more commonly in older men .
histological examination shows increased elastic tissue with thickened , tortuous fibers in the upper and mid dermis .
elastotic nodule(s ) of the ear is characterized by single or multiple bilateral , firm to hard pale nodules on the antihelix or helix .
histological features include irregular coarse , elastotic material and clumped masses of thick fibers on a background of marked solar elastosis .
clinically , they may resemble basal cell carcinoma , amyloidosis , gouty tophi and chondrodermatitis nodularis helicis .
collagenous and elastotic plaques of the hands is a slowly progressive condition more often found in older men with waxy linear plaques at the junction of the dorsal and palmar skin on the hand .
histological examination shows amorphous basophilic elastotic masses and thickened , fragmented , calcified elastic fibers in the upper and mid dermis .
the thick collagen bundles have a haphazard arrangement , but with a proportion running perpendicular to the surface .
adult colloid milium , another solar elastotic dermatosis , is the closest clinical differential diagnosis of papular elastosis .
light microscopy shows accumulation of a homogenous , amorphous faintly eosinophilic material with cleft - like spaces in the upper and mid dermis .
the cause for the colloid deposition in the dermis is still uncertain , but some authors have suggested that it is from degeneration of collagen and/or elastic fibers due to actinic action . there is also a possibility that this elastotic material is newly formed from sun - damaged fibroblast . interestingly , both our patients were on immunosuppressive therapy and they both had dual agents .
there is strong evidence that organ transplant recipients on immunosuppressive therapy have an increased risk of actinic damage and skin cancers [ 12 , 13 , 14 ] .
it has also been reported that transplant recipients with a history of skin cancer may experience a deceleration of cutaneous carcinogenesis after stopping immunosuppressants .
further research work is needed to elucidate the molecular mechanisms of immunosuppression leading to an acceleration of solar elastosis . in summary , we have presented two cases of papular elastosis that occurs in chronically sun - damaged skin .
it is necessary to obtain biopsy confirmation as this condition is very rare , and important differential diagnoses such as basal cell carcinoma need to be ruled out .
the most effective strategy to manage solar elastosis is prevention of actinic - related damage with sun avoidance , protective clothing and sunscreen .
 solar elastosis is a degenerative condition of elastic tissue in the dermis due to prolonged sun exposure . 
 there are a variety of clinical manifestations of solar elastosis . in its most common form 
 , solar elastosis manifests as yellow , thickened , coarsely wrinkled skin . 
 we report two uncommon cases of severe solar elastosis with a papular morphology . 
 its presentation can closely mimic a host of cutaneous disorders and thus , although it is helpful to be cognizant of this entity , it is still crucial to biopsy these lesions to avoid missing a more sinister condition . 
Introduction
Case 1
Case 2
Discussion and Review of the Literature