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pemphigus vegetans ( pveg ) is a rare variant of pemphigus vulgaris ( pv ) and accounts for < 5% of pemphigus cases .
. however , distinction of these 2 clinical forms as well as differentiation from pv is not always possible .
the more frequent neumann type displays periorificial papillomatous vegetations , whereas the hallopeau type is characterized by pustules evolving into vegetations particularly affecting the intertriginous areas [ 1 , 2 ] .
whether pveg is a distinct entity or just a special phenotype of pv is still controversial .
unusual or atypical manifestations of pveg may pose a diagnostic challenge resulting in delayed diagnosis .
a broad spectrum of differential diagnoses must be considered depending on the clinical manifestation and distribution of the lesions . as in pv ,
the diagnosis of pveg is confirmed via direct and indirect immunofluorescence ( if ) microscopy and detection of anti - desmoglein ( dsg ) 3 and/or anti - dsg1 antibodies .
in addition , anti - desmocollin ( dsc ) 1 , 2 , and 3 antibodies were detected in some patients [ 3 , 4 , 5 , 6 ] .
we here report a case of pveg with initially exclusive involvement of the ring finger 's tip of the right hand representing per se a diagnostic challenge that was associated with an unusual constellation of anti - dsg3 antibodies . to compare our patient 's antibody profile with autoimmunological findings of previously described patients suffering from pveg
, we performed a literature research considering all cases of pveg published in the english - speaking literature .
a 64-year - old caucasian man was referred with a 6-week history of a sharply bordered erythematous plaque affecting the ring finger 's tip of the right hand . despite antimicrobial treatment with several antibiotics ( cefuroxime , ampicillin , clindamycin , ciprofloxacin ) and anti - inflammatory topical treatment with betamethasone valerate , skin lesions progressed and finally led to loss of the nail .
the patient had a medical history of perichondritis , an untreated arterial hypertension , as well as a panic disorder .
physical examination revealed a plaque with overlying crusts and annular pustules on erythematous ground on the fourth right digit ( fig .
bacterial swabs of the finger revealed colonization with enterococcus faecalis , escherichia coli , morganella morganii , and gram - positive cocci , while tests for fungal infections were negative .
in addition to bacterial and fungal infections , differential diagnoses including vegetating herpes simplex infection , acrodermatitis continua suppurativa , pyoderma gangraenosum , bowen 's disease , and squamous cell carcinoma were considered and excluded .
histopathology showed eosinophilic pustule formation in the epidermis in concert with acantholysis and a superficial eosinophil - rich lymphocytic infiltrate ( fig .
finally , the diagnosis was confirmed by direct if microscopy of perilesional skin revealing intercellular deposits of igg antibodies in the epidermis ( fig .
indirect if microscopy on monkey esophagus allowed detection of igg antibodies binding with an intercellular pattern .
although mucous membranes were initially not involved , high levels of circulating anti - dsg3 antibodies ( 2,644 u / ml ; normal : > 20 u / ml ) but no anti - dsg1 antibodies were detected by elisa ( mesacup desmoglein 1 and 3 , mbl , nagoya , japan ) .
in addition , indirect if using desmocollin ( dsc)-transfected hek293 cells as substrate revealed absence of circulating iga and igg autoantibodies against dsc1 , 2 , and 3 ( data not shown ) .
a high - dose intravenous steroid pulse therapy ( 100 mg dexamethasone on 3 consecutive days ) was initiated and repeated after 2 weeks .
having ensured normal thiopurine methyltransferase activity , azathioprine was started ( 1.4 mg / kg body weight per day ) but had to be discontinued due to drug - related liver toxicity .
instead , mycophenolate mofetil ( mmf ) was administrated ( 2 g per day ) .
two weeks after the second intravenous steroid pulse , anti - dsg3 antibody levels notably decreased to 237 u / ml ( fig .
for the first time , the patient developed erosions of the oral mucosa going along with involvement of several fingers and aggravation of the vegetations in the perianal region .
worsening of disease was reflected by an increase of serum autoantibody levels ( anti - dsg3 igg : 3,328 u / ml ; anti - dsg1 igg : 30 u / ml ) ( fig .
in addition , the patient experienced several depressive episodes linked to his preexisting panic disorder . finally , therapy with rituximab ,
rituximab was administrated twice at a dose of 1 g in a 2-week interval while mmf was continued .
unfortunately , clinical response could not be assessed as the patient was lost to follow - up .
unusual or atypical manifestations of pveg are prone to be misdiagnosed or misinterpreted , which may result in delayed correct diagnosis . in case of solitary lesions or uncommon localization of pveg
acrodermatitis continua suppurativa was considered , but neither the patient 's nor the family history or the clinical examination was remarkable for psoriasis .
finally , the diagnosis of pveg of the hallopeau type was established by the results of histopathology , direct if microscopy , and serology . strikingly , the initial detection of anti - dsg3 antibodies in the absence of anti - dsg1 antibodies without mucosal involvement was puzzling . to compare our patient 's antibody profile with autoimmunological findings of previously described patients suffering from pveg
, we reviewed the anglophone literature from december 1988 to january 2017 , considering all available full - text publications providing information on mucous membranes and/or skin involvement and autoantibody levels ( at least anti - dsg1 and/or anti - dsg3 reactivity ; table 1 ) [ 2 , 3 , 4 , 5 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ] .
thirty - one publications reporting results of 52 patients were identified ( pveg , n = 48 ; pemphigoid vegetans ( bpveg)/pveg , n = 1 ; paraneoplastic pemphigus / pveg , n = 3 )
. in 35 patients , the provided information concerning clinical picture and immunological findings enabled us to correlate involvement of the skin and/or mucous membranes with anti - dsg1 and/or anti - dsg3 antibody levels . in 24 patients ,
ten patients suffered from skin lesions only [ 3 , 5 , 8 , 13 , 15 , 17 , 22 , 31 , 32 ] .
notably , in 7 of these , as in our patient , anti - dsg3 antibodies were detected although mucous membranes were spared [ 8 , 13 , 15 , 17 , 22 , 31 , 32 ] .
these findings are not consistent with the desmoglein compensation hypothesis that explains the tissue specificity of the autoantibody - induced loss of cell adhesion in pemphigus . according to this hypothesis
in recent years our understanding of the pemphigus pathogenesis considerably increased and the  monopathogenetic 
explanation has been questioned . while the compensation theory basically described acantholysis - introducing effects of anti - dsg antibodies , actually other pathogenic effects ( like induction of acanthosis or accumulation of neutrophils ) of anti - dsg antibodies
there is evidence that , apart from dsg1 and dsg3 , additional organ - specific and non - organ - specific antigens are targeted by autoantibodies . besides dsg 14 , there are 3 other cadherins in the epidermal desmosomes , namely dsc1 , dsc2 , and dsc3 .
anti - dsc3 igg antibodies have been detected in sera of patients with atypical variants of pemphigus such as pveg [ 3 , 5 , 6 ] . moreover ,
anti - dsc1 iga antibodies were found in patients suffering from subcorneal pustular dermatosis type of iga pemphigus . in the patient presented here ,
no anti - dsc1 , 2 or 3 antibodies were detected in the serum via if using dsc - transfected hek293 cells as substrate .
however , it was recently shown that the sensitivity of novel elisas using recombinant , mammalian proteins was higher than that of if .
as in our patient , unusual manifestations of pveg may mimic various skin diseases and pose a diagnostic challenge .
notably , the detection of anti - dsg1 and anti - dsg3 antibodies does not necessarily correlate with the involvement of skin and/or mucous membranes .
this might be due to more specific and complex antibody constellations in nonclassical or atypical pemphigus .
the further development and implementation of new diagnostic approaches such as the detection of serum anti - dsc antibodies on a routine basis may clarify this observation .
all authors declare that there are no conflicts of interest regarding the publication of this case report .
pemphigus vegetans ( pveg ) is a rare variant of pemphigus vulgaris characterized by pustules and/or papillomatous vegetations , preferentially affecting intertriginous and periorificial areas . 
 exceptional manifestations may be misdiagnosed resulting in delayed diagnosis and treatment . 
 diagnosis is confirmed by immunofluorescence and detection of anti - desmoglein ( dsg ) 3 and/or anti - dsg1 antibodies . 
 we herein report an unusual manifestation of pveg . at the time of first presentation 
 , lesions were restricted to the right ring finger 's tip . 
 although mucous membranes were initially not affected , high levels of anti - dsg3 antibodies were detected while anti - dsg1 and anti - desmocollin ( dsc ) 1 , 2 , and 3 antibodies were absent . to compare our immunological findings with previous reports , all accessible anglophone literature published since december 1988 was evaluated . 
 we identified 52 patients suffering from pveg , 7 of these showed anti - dsg3 antibodies without any mucous membrane involvement . 
 notably , the detection of anti - dsg1 and anti - dsg3 antibodies does not necessarily correlate with the involvement of skin and/or mucous membranes . 
 this might be due to more specific and complex antibody constellations in nonclassical or atypical pemphigus .