the incidental finding of focal acantholytic dyskeratosis , first described by ackerman , is a common occurrence [ 14 ] . papular acantholytic dyskeratoma  has been used to describe a solitary lesion on the lip , whereas , papular acantholytic dyskeratosis  has been used to describe numerous lesions of genital location [ 616 ] . however , non - genital lesions characterized by acantholysis and dyskeratosis have been difficult to properly identify and interpret . solitary , non - genital lesions with prominent acantholysis and dyskeratosis without cup - shaped architecture or follicular involvement have been described as a distinct histologic entity : acantholytic dyskeratotic acanthoma . we present a patient who developed an acantholytic dyskeratotic acanthoma and summarize the acantholytic dyskeratotic acanthomas ( 30 cutaneous and 3 subungual ) that have been described in literature during the past 30 years . a 72-year - old white woman presented for evaluation of a painful lesion beneath her left breast . it appeared three months earlier as a non - healing , tender , raised area with central erosion . she had no personal or family history of keratosis follicularis ( darier s disease ) , transient acantholytic dermatosis ( grover s disease ) , non - melanoma skin cancer or melanoma . cutaneous examination revealed a 10  4 mm plaque beneath the left breast ( figure 1 ) . focal areas of acantholysis , involving all layers of the epidermis , were also observed . in the dermis correlation of the clinical presentation and pathologic findings established the diagnosis of an acantholytic dyskeratotic acanthoma . focal acantholytic dyskeratosis was first coined by ackerman in 1972 in an attempt to describe a distinctive histologic pattern with parakeratotic hyperkeratosis , acantholytic dyskeratosis ( at all levels of the epidermis ) , and focal suprabasilar clefts . he classified the lesions by size , number ( single or multiple ) , and duration ( persistent and transient ) leading to six distinct classes : ( 1 ) incidental , ( 2 ) multiple lesions ( darier s disease ) , ( 3 ) nodular with follicular involvement ( warty dyskeratoma ) , ( 4 ) papular , ( 5 ) systematized , and ( 6 ) transient ( grover s disease ) . the majority of his patients had lesions that were similar to those subsequently observed , clinically unapparent and histologically incidental ( 3 ] . two patients with the papular subtype of focal acantholytic dyskeratosis , diagnosed as seborrheic keratosis and basal cell carcinoma , appeared to have features that are similar to those now established as acantholytic dyskeratotic acanthomas . subsequently , omulecki et al . described a patient who had a single plaque with bimodal histology of acantholysis and dyskeratosis , and introduced the term acantholytic dyskeratotic acanthoma . thereafter , ko et al . did a retrospective study and described 28 patients who had a solitary , non - genital lesion with acantholysis and dyskeratosis ; however , the lesion did not have a cup - shaped , cystic architecture or follicular involvement . nail findings of focal acantholytic dyskeratosis were first described by isonokami and higashi in the japanese literature in 1990 . however , it was not until nearly two decades later that sass et al . reported 3 patients with acantholysis and dyskeratosis of the thumb nail bed epithelium as acantholytic dyskeratotic acanthoma . there is currently neither a world health organization statement nor an agreement in explicative dermatopathology whether acantholytic dyskeratotic acanthoma is a distinct entity . indeed , in lever s histopathology textbook acantholytic dyskeratosis is described as a phenomena and not a separate entity . in contrast , in weedon s latest textbook some authors consider cutaneous acantholytic dyskeratotic acanthoma to be a separate entity , which usually clinically presents as a basal cell carcinoma . we concur with ko et al . that cutaneous acantholytic dyskeratotic acanthoma is a separate entity with a distinctive clinical morphology and corresponding pathologic features . our review includes 30 patients with cutaneous acantholytic dyskeratotic acanthoma and 3 patients with subungual acantholytic dyskeratotic acanthoma ( table 1 ) [ 1,1720,23 ] . their onset age ranged from 39 years to 84 years with a median of 54 years . cutaneous acantholytic dyskeratotic acanthoma is more common in women , whereas subungual acantholytic dyskeratoma is more common in men . in contrast , the ratio of women to men with subungual acantholytic dyskeratotic acanthoma was 1:2 . the cutaneous lesions were between 29 mm , with a median size of 5 mm . ( 83% , 25 of 30 ) was the trunk ; the other site included the extremities ( 17% , 5 of 30 ) . all of the subungual lesions presented with monodactylous , solitary longitudinal erythronychia of the thumbnail . the solitary red band extended from the matrix to the distal part of the nail apparatus . confluent acantholytic dyskeratosis affecting the entire thickness of the epidermis was noted in 19 patients . confluent acantholytic dyskeratosis localized only to the granular and corneal layer of the epidermis was observed in 3 patients . non - confluent focal sites of acantholytic dyskeratosis were present in 8 of the patients , including the patient reported herein and by omulecki et al . specifically , our patient had two foci of intra - epidermal acantholysis with overlying parakeratosis and focal dyskeratosis ; focal horn cyst formation was also noted . focal acantholytic dyskeratosis was first coined by ackerman in 1972 in an attempt to describe a distinctive histologic pattern with parakeratotic hyperkeratosis , acantholytic dyskeratosis ( at all levels of the epidermis ) , and focal suprabasilar clefts . he classified the lesions by size , number ( single or multiple ) , and duration ( persistent and transient ) leading to six distinct classes : ( 1 ) incidental , ( 2 ) multiple lesions ( darier s disease ) , ( 3 ) nodular with follicular involvement ( warty dyskeratoma ) , ( 4 ) papular , ( 5 ) systematized , and ( 6 ) transient ( grover s disease ) . the majority of his patients had lesions that were similar to those subsequently observed , clinically unapparent and histologically incidental ( 3 ] . two patients with the papular subtype of focal acantholytic dyskeratosis , diagnosed as seborrheic keratosis and basal cell carcinoma , appeared to have features that are similar to those now established as acantholytic dyskeratotic acanthomas . subsequently , omulecki et al . described a patient who had a single plaque with bimodal histology of acantholysis and dyskeratosis , and introduced the term acantholytic dyskeratotic acanthoma . thereafter , ko et al . did a retrospective study and described 28 patients who had a solitary , non - genital lesion with acantholysis and dyskeratosis ; however , the lesion did not have a cup - shaped , cystic architecture or follicular involvement . nail findings of focal acantholytic dyskeratosis were first described by isonokami and higashi in the japanese literature in 1990 . however , it was not until nearly two decades later that sass et al . reported 3 patients with acantholysis and dyskeratosis of the thumb nail bed epithelium as acantholytic dyskeratotic acanthoma . there is currently neither a world health organization statement nor an agreement in explicative dermatopathology whether acantholytic dyskeratotic acanthoma is a distinct entity . indeed , in lever s histopathology textbook acantholytic dyskeratosis is described as a phenomena and not a separate entity . in contrast , in weedon s latest textbook some authors consider cutaneous acantholytic dyskeratotic acanthoma to be a separate entity , which usually clinically presents as a basal cell carcinoma . we concur with ko et al . that cutaneous acantholytic dyskeratotic acanthoma is a separate entity with a distinctive clinical morphology and corresponding pathologic features . our review includes 30 patients with cutaneous acantholytic dyskeratotic acanthoma and 3 patients with subungual acantholytic dyskeratotic acanthoma ( table 1 ) [ 1,1720,23 ] . their onset age ranged from 39 years to 84 years with a median of 54 years . cutaneous acantholytic dyskeratotic acanthoma is more common in women , whereas subungual acantholytic dyskeratoma is more common in men . in contrast , the ratio of women to men with subungual acantholytic dyskeratotic acanthoma was 1:2 . the cutaneous lesions were between 29 mm , with a median size of 5 mm . ( 83% , 25 of 30 ) was the trunk ; the other site included the extremities ( 17% , 5 of 30 ) . all of the subungual lesions presented with monodactylous , solitary longitudinal erythronychia of the thumbnail . the solitary red band extended from the matrix to the distal part of the nail apparatus . confluent acantholytic dyskeratosis affecting the entire thickness of the epidermis was noted in 19 patients . confluent acantholytic dyskeratosis localized only to the granular and corneal layer of the epidermis was observed in 3 patients . non - confluent focal sites of acantholytic dyskeratosis were present in 8 of the patients , including the patient reported herein and by omulecki et al . specifically , our patient had two foci of intra - epidermal acantholysis with overlying parakeratosis and focal dyskeratosis ; focal horn cyst formation was also noted . the most common clinical diagnoses of cutaneous acantholytic dyskeratotic acanthoma were either a nonmelanoma skin cancer ( basal cell carcinoma in 15 patients or squamous cell carcinoma in 9 patients ) or an actinic keratosis ( 5 patients ) . less common diagnoses were seborrheic keratosis ( 3 patients ) , nevus ( 2 patients ) , or wart ( 2 patients ) . onychopapilloma , which can morphologically present as a monodactylous single red band , was the suggested diagnosis , prior to biopsy , in the 3 patients with subungual acantholytic dyskeratotic acanthoma . other diagnoses of longitudinal erythronychia included glomus tumor , malignant neoplasms ( such as melanoma and squamous cell carcinoma ) , and warty dyskeratoma . the co - existence of acantholysis and dyskeratosis is present in a few distinct conditions . keratosis follicularis ( darier s disease ) has focal orthokeratotic plugs , full epidermal acantholysis leading to the formation of suprabasal clefts ( lacuna ) , and corneal and granular dyskeratosis ( corps ronds and grains ) . warty dyskeratoma typically has a cup - shaped invagination into underlying dermis and follicular involvement ; in addition to clefting and corps ronds , prominent villi may also be observed . table 2 summarizes the pathologic features that can differentiate acantholytic dyskeratotic acanthoma from warty dyskeratoma . the absence multi - nucleated epidermal giant cells in acantholytic dyskeratotic acanthoma differentiates it from herpes simplex and varicella - zoster skin lesions . incidental acanthosis or dyskeratosis may be occasionally noted in an actinic keratosis , basal cell carcinoma , or squamous cell carcinoma ; however , the absence of nuclear atypia differentiates acantholytic dyskeratotic acanthoma from those conditions . in contrast to acantholytic dyskeratotic acanthoma , subungual warty dyskeratoma has a prominent papillomatous pattern ; also , the acantholysis and dyskeratosis occur within a crater - like shape . none of the patients had family history of keratosis follicularis ( darier s disease ) ; however , specific genetic studies had not been performed . testing for atp2a2 gene mutations is an emerging diagnostic tool for the distinction between darier s and grover s diseases . evaluating for mutations in this gene may be useful in further elucidating the developmental pathway of acantholytic dyskeratotic acanthoma in patients with cutaneous or subungual lesions . our patient s lesion was entirely excised at the time of biopsy and healed without evidence of recurrence at the subsequent visit . the most common clinical diagnoses of cutaneous acantholytic dyskeratotic acanthoma were either a nonmelanoma skin cancer ( basal cell carcinoma in 15 patients or squamous cell carcinoma in 9 patients ) or an actinic keratosis ( 5 patients ) . less common diagnoses were seborrheic keratosis ( 3 patients ) , nevus ( 2 patients ) , or wart ( 2 patients ) . onychopapilloma , which can morphologically present as a monodactylous single red band , was the suggested diagnosis , prior to biopsy , in the 3 patients with subungual acantholytic dyskeratotic acanthoma . other diagnoses of longitudinal erythronychia included glomus tumor , malignant neoplasms ( such as melanoma and squamous cell carcinoma ) , and warty dyskeratoma . the co - existence of acantholysis and dyskeratosis is present in a few distinct conditions . keratosis follicularis ( darier s disease ) has focal orthokeratotic plugs , full epidermal acantholysis leading to the formation of suprabasal clefts ( lacuna ) , and corneal and granular dyskeratosis ( corps ronds and grains ) . warty dyskeratoma typically has a cup - shaped invagination into underlying dermis and follicular involvement ; in addition to clefting and corps ronds , prominent villi may also be observed . table 2 summarizes the pathologic features that can differentiate acantholytic dyskeratotic acanthoma from warty dyskeratoma . the absence multi - nucleated epidermal giant cells in acantholytic dyskeratotic acanthoma differentiates it from herpes simplex and varicella - zoster skin lesions . incidental acanthosis or dyskeratosis may be occasionally noted in an actinic keratosis , basal cell carcinoma , or squamous cell carcinoma ; however , the absence of nuclear atypia differentiates acantholytic dyskeratotic acanthoma from those conditions . in contrast to acantholytic dyskeratotic acanthoma , subungual warty dyskeratoma has a prominent papillomatous pattern ; also , the acantholysis and dyskeratosis occur within a crater - like shape . none of the patients had family history of keratosis follicularis ( darier s disease ) ; however , specific genetic studies had not been performed . testing for atp2a2 gene mutations is an emerging diagnostic tool for the distinction between darier s and grover s diseases . evaluating for mutations in this gene may be useful in further elucidating the developmental pathway of acantholytic dyskeratotic acanthoma in patients with cutaneous or subungual lesions . our patient s lesion was entirely excised at the time of biopsy and healed without evidence of recurrence at the subsequent visit . the term focal acantholytic dyskeratosis was originally used to describe incidental lesions with acantholysis and dyskeratosis ; however , when these findings occur as a distinct , non - genital lesion of the skin or under the nail , we concur with current nomenclature of acantholytic dyskeratotic acanthoma . specifically , we consider acantholytic dyskeratotic acanthoma to be a clinically and pathologically distinct lesion , which may morphologically present as either truncal plaques or subungual longitudinal erythronychia . our patient was a 72-year - old woman with a non - healing eroded plaque underneath the breast . in our review of the literature , we were able to find 30 patients whose skin lesions presented as solitary , non - genital plaque , usually between 5 mm to 1 cm in size . we also found 3 patients ( 2 men and 1 woman ) with subungual acantholytic dyskeratotic acanthoma of the thumb . clinically , cutaneous acantholytic dyskeratotic acanthoma most resembled a nonmelanoma skin cancer or actinic keratosis and subungual acantholytic dyskeratotic acanthoma was suspected to be an onychopapilloma . three histological patterns of acantholytic dyskeratotic acanthoma were described : ( 1 ) confluent acantholytic dyskeratosis involving all layers of the epidermis seen in 19 patients , ( 2 ) confluent acantholytic dyskeratosis within granular and corneal layers seen in 3 patients , and ( 3 ) focal acantholytic dyskeratosis seen in 8 patients . the pathologic differential diagnosis of acantholytic dyskeratotic acanthoma includes darier s disease , grover s disease , and warty dyskeratoma ; however , acantholytic dyskeratotic acanthoma can be differentiated from the solitary warty dyskeratoma by the absence of cup - shaped architecture and the absence of follicular involvement . the pathogenesis of acantholytic dyskeratoma remains to be discovered and excision appears to be the definitive treatment .
background : focal acantholytic dyskeratosis has been described as an incidental finding and as a clinically distinct lesion . in both situations , 
 a dimorphic histologic pattern is observed : acantholysis and dyskeratosis . 
 solitary , non - genital lesions displaying such pathology have been difficult to classify . 
 clinical and pathological characteristics of acantholytic dyskeratotic acanthomas are described.methods:the features of a patient with solitary , non - genital , acantholytic dyskeratotic acanthoma are presented and the literature on acantholytic dyskeratotic acanthomas is reviewed . using pubmed 
 the following terms were searched and relevant citations assessed : acantholysis , acanthoma , cutaneous , dyskeratosis , nail , warty.results:we identified 30 cutaneous acantholytic dyskeratotic acanthomas , including our patient , most often found on the trunk and mimicking basal cell carcinoma , and three subungual acantholytic dyskeratotic acanthomas of the thumb , which mimicked onychopapilloma.conclusion:acantholytic dyskeratotic acanthomas are clinically and pathologically distinct lesions , which may morphologically present as either truncal plaques or subungual longitudinal erythronychia .