circumscribed palmo - plantar hypokeratosis ( cph ) is a rare dermatosis , first described by perez et al . in 2002 .
only about 50 cases have been described in the literature so far , of which two were with a unique plantar localization .
the disorder usually affects women ( with a female : male ratio of 4:1 ) , with a mean age of presentation of 61 years .
it presents clinically with annular erythematous depressed patch rimmed by a slightly hyperkeratotic border ; the lesion is usually unique and localized over the thenar or hypothenar eminence of the palms , rarely on the soles .
cph presents clinical stereotypical features even if sometimes it is misdiagnosed as palmar porokeratosis or bowen 's disease .
its main histopathologic feature shows a characteristic epidermal depression with an abrupt decrement in the thickness of the stratum corneum , with a sharp stair
a 68-year - old woman presented with an acquired , asymptomatic , slowly enlarging erythematous patch on the thenar eminence of her right hand .
her medical history included a mammary adeno - carcinoma treated with surgery and radio - therapy 10 years before .
examination revealed over the right eminence thenar an approximately 15  10 mm , well - circumscribed circular erythematous area , depressed , with sharp step between involved and uninvolved skin [ figure 1 ] .
histopathology showed a sharply demarcated depressed area with markedly thinned stratum corneum with normal basal layers .
slight dilatation of the dermal superficial vessels was noted , with poor lymphocytic infiltration and edema . there was no evidence of cornoid lamella excluding a diagnosis of porokeratosis .
corneocytes of the upper layers showed signs of vacuolization and they became eosinophilic at the edge [ figure 2 ] . based on these findings
the patient is currently on clinical follow - up and in 7 years there has been no evidence of enlargement or evolution . a circular and well - circumscribed area of depressed and erythematous skin on the right thenar eminence skin biopsy specimen from border of the lesion : sharp step - off from the thick stratum corneum of normal acral skin to the thin stratum corneum of the involved skin ( hematoxylin  eosin staining ; original magnification 200 )
cph is a benign dermatosis of unknown origin predominantly seen in adult women ( female : male ratio 4:1 ; mean age 61 years ) .
argued that it is a localized acquired epidermal malformation because of the presence of the lesions for many years and the absence of a trauma at the site of the lesions .
using transmission electron microscopy , showed a reduction in keratin bundles and keratohyaline granules , and increased lipid in the horny layer , suggesting a primary disorder of keratinization .
in contrast to these studies , resnik et al . suggested that circumscribed palmar or plantar hypokeratosis represents a localized defect in the maturation of keratin , which could follow subclinical episodes of trauma . in
interestingly , in this case the lesion had been present for an unusual short time of 6 months .
cph is chronic dermatosis with a benign evolution ; the lesions slowly progress or remain stable over years as in our case . only in one recently reported case
the lesions typically involve the thenar and hypothenar eminences of the palm or the medial side of the sole .
clinically they appear as circular and well - circumscribed areas of depressed and erythematous skin with slightly elevated scaly borders . in most cases ,
histopathologic features are characteristic and they consist of a localized depression of the epidermis , with a sharp stair between normal and involved skin .
the stratum corneum is thinner and orthokeratotic , with a stratum granulosum slightly decreased compared to the adjacent non - involved skin .
, a biopsy should be performed at the border 's lesion to compare the horny layer of the involved skin with that of the non - involved adjacent skin . in literature ,
various topical treatments are proposed , including corticosteroids , salicylic acid and retinoids , but they all have been disappointing .
urbina et al . reported resolution in one case after 4 years of topical therapy with calcipotriol .
boffa and de gaetano reported a case of resolution after treatment with liquid nitrogen cryotherapy .
no improvement was evident after treatment with a topical steroid for 3 months . in summary
as has been described in literature , we did not find evidence of trauma as an inciting factor in our case .
unlike another reported case , we did not identify evidence of hpv within lesions by immunohistochemistry .
we consider this disorder as an acquired non - inflammatory defect in keratinization on acral sites with a remote potential of malignant transformation ; for this reason , we consider a prolonged clinical follow - up essential , as in our case .
 circumscribed palmar or plantar hypokeratosis is a rare benign epidermal malformation of the skin . 
 clinically it shows asymptomatic , well - circumscribed , and depressed erythema persisting for many years on the palms or soles . 
 its main histopathologic feature shows a characteristic epidermal depression with an abrupt decrement in the thickness of the stratum corneum , with a sharp stair between normal and involved skin . 
 we describe a case of a 68-year - old woman who presented with an erythematous , asymptomatic , well - circumscribed , depressed patch , on the right thenar eminence which had been present for years . 
Introduction
Case Report
Discussion