bowen 's disease is a form of squamous cell carcinoma in situ , which may progress to invasive squamous cell carcinoma . it presents as a solitary , erythematous plaque with crusting and scaling usually on sun - exposed areas and may be mistaken clinically for localized psoriasis or lupus vulgaris . bowen 's disease ( bd ) is an in - situ squamous cell carcinoma ( scc ) , which shows tendency towards lateral spread . if not treated , about 3 - 5% of this condition can progress into invasive squamous cell carcinoma that can metastatize and may even lead to death . a case of unusual acantholytic variant of bowen 's disease developing micro - invasive squamous cell carcinoma is presented for its rarity . a 44-year - old indian male presented with a 2-year history of gradually enlarging pigmented skin lesion of his left arm with occasional itching . physical examination revealed slightly elevated hyperpigmented plaque measuring 6  4 cms with well - defined borders and mild scaling over the lateral aspect of his left arm [ figure 1 ] . an incisional biopsy was taken with a clinical differential diagnosis of bowen 's disease , localized psoriasis , and lupus vulgaris . clinical picture showing large erythematous , crusted plaque on the forearm histopathological examination of the incisional biopsy from the lesion showed entire thickness of the epithelium exhibiting atypical keratinocytes with altered polarity , exhibiting marked nuclear pleomorphism , hyperchromasia and increased number of atypical mitosis [ figure 2a and b ] . also seen was intra - epidermal bulla / cleft formation in the suprabasal location and the presence of acantholytic anaplastic keratinocytes within the bulla [ figure 3 ] . a diagnosis of bowen 's disease - acantholytic variant ( squamous cell carcinoma in - situ ) was made and a wide excision of the lesion was advised . ( a ) ( b ) showing nuclear pleomorphism with altered polarity , increased mitosis and apoptosis , h and e , 200 photomicrograph shows intra epidermal villi formation due to acantholysis , h and e , 200 following the diagnosis , patient underwent wide surgical excision of the lesion . multiple sections from the lesion revealed carcinoma in situ with extension of atypical keratinocytes into the follicular epithelium [ figure 4 ] . microscopic invasion of the basement membrane with infiltration by malignant cells of the superficial dermis was noted , surrounded by inflammatory infiltrate and stromal desmoplasia [ figure 5 ] . a final diagnosis of acantholytic variant of bowen 's disease with micro - invasive squamous cell carcinoma was made . photomicrograph shows dysplasia involving the epithelium of hair follicles in the dermis , h and e , 100 photomicrograph shows disruption of basement membrane and invasion of dermis by malignant squamous cells surrounded by dense inflammatory infiltrate and stromal desmoplasia , h and e , 200 in 1912 , bowen reported a study of two cases of chronic atypical epithelial proliferation to which he gave the designation of precancerous dermatosis . bd is most commonly seen in elderly individuals and presents clinically as a macule , papule , or a plaque . the borders are usually well demarcated from the surrounding skin , and the size may range from few millimeters to several centimeters in size . for most of the cases , it usually occurs in sun - exposed areas , but can also occur in ano - genital region , oral mucosa , nail bed , and conjunctiva . in the skin , bowen 's disease is associated with sun exposure , but in anal and genital region , high risk hpv genotypes are implicated in the etiology . usually bd is a solitary lesion , but in 10% to 20% it occurs at multiple sites . the risk of progression into an invasive carcinoma is 3% to 5% in extragenital lesions and about 10% in genital lesions . bd is very common in the caucasian population with an incidence of 1.42 per 1,000 in some populations . histological examination of the lesion is important in order to identify whether it is benign or malignant . it also helps in differentiating lesions due to actinic keratosis , basal cell carcinoma , squamous cell carcinoma , seborrheic keratosis , psoriasis , and eczema . bd is characterized histologically by hyperkeratosis , parakeratosis , and acanthosis with thickened and elongated rete ridges . the keratinocytes show loss of maturity and polarity , giving the epidermis a disordered or  windblown  appearance . several histological subtypes such as psoriasiform , atrophic , epidermolytic and acantholytic , pagetoid variants are described . fitzpatrick describes this phenomenon in bowen 's disease ; however , there is paucity of reports describing acantholytic variant of bowen 's disease . both bowen 's disease and actinic keratosis are intraepidermal squamous cell carcinomas with potential progression to invasive squamous cell carcinoma . histologically , bowen 's disease shows highly atypical cancer cells with clumping with complete disorder throughout the epidermis , while actinic keratosis shows milder degree of atypia of keratinocytes without full thickness involvement . bd can also be differentiated from bowenoid ak by the presence of dysplasia involving the follicular epithelium . acantholysis due to lack of cohesion between keratinocytes with the formation of intra - epidermal bullae and clefts has been described in a wide variety of benign and malignant skin diseases such as actinic keratosis , paget 's disease , melanocytic nevi , adenoid squamous cell carcinoma , and others . various treatment modalities such as surgery , curettage , cautery , cryotherapy , and topical therapies are widely in use for the treatment of this disease . surgical excision is generally considered the treatment of choice for most lesions of this disease , if the size and location of the lesion permit , with a cure rate of 95% . however , some studies report potential drawbacks of surgical excision with a high potential for incomplete excision and persistent disease , even after complete excision in some patients , and a high morbidity rate . topical agents like 5-fu and imiqiumod can give good results and should be applied for 4 - 16 weeks once daily . whether acantholytic variant of bowen 's disease behaves differently from the usual type is not clear due to paucity of reports on this unique variant of bowen 's disease . a uncommon histological variant acantholytic bowen 's disease is presented for its rarity , and differentiation from acantholytic variant of actinic keratosis is discussed .
bowen 's disease is generally regarded as premalignant dermatoses . 
 the disease affects both skin and the mucosa and has the potential to progress to invasive squamous cell carcinoma . 
 there are descriptions of several histological variants of bowen 's disease like psoriasiform , atrophic , pagetoid , etc . 
 acantholysis of anaplastic keratinocytes with bullae / cleft formation is described in premalignant condition like actinic keratosis and adenoid variant of squamous cell carcinoma , but there is lack of report describing this phenomena in bowen 's disease . 
 we present a case of unusual acantholytic variant of bowen 's disease with focus of micro - invasive carcinoma .