the frequency of umbilical cord blood transplantation ( cbt ) from unrelated donors has increased among adult patients who require allogeneic hematopoietic stem cell transplantation but have no suitable bone marrow or peripheral blood stem cell donors . although very rare , there are reports of patients who have undergone cbt and subsequently developed cutaneous disseminated vzv infection . there is a lack of detailed information on the clinical course and serological findings in such cases . here , we report in detail the clinical course and serological findings of a case of vzv reinfection in an adult post cbt , which appeared clinically to be varicella and followed a severe and prolonged course . a 50-year - old japanese man with a history of cbt for acute lymphoblastic leukemia in march 2009 developed remittent fever and fatigue on 25 august 2010 . subsequently , he noticed an itchy skin eruption and visited our dermatology department on 1 september , 2010 . physical examination revealed sparsely distributed vesicles , some with umbilication , and small erythematous erosions on the face , anterior chest , upper back , and upper extremities [ figure 1a , b ] . histological analysis of a vesicle showed an intraepidermal blister containing degenerated balloon cells [ figure 1c , d ] . within a few days , there was widespread eruption of vesicles and bullae over the body [ figure 1e , f ] and the fever became continuous . clinical appearance of the skin lesions at day 3 : ( a ) erythematous erosion in the region of the left eyebrow and ( b ) an umbilicated vesicle . histological findings in a vesicle on the right forearm : ( c ) acanthosis with intraepidermal blisters and a mild perivascular infiltration of lymphocytes in the upper dermis ( hematoxylin and eosin ; original magnification 40 ) and ( d ) an intraepidermal blister containing degenerated balloon cells ( hematoxylin and eosin ; original magnification 200 ) . clinical appearance of the skin lesion at day 10 : scattered vesicles and bulla , some of which became erosions on the chest , abdomen ( e ) , and back ( f ) he was admitted for intravenous acyclovir ( 10 mg / kg / day ) for 5 days , with a reduced dose as the patient had renal dysfunction of an unknown cause . the skin lesions responded promptly to therapy : no new skin lesions developed and the bullous lesions began to scab , though some lesions remained active . the patient was discharged after 5 days of intravenous acyclovir , with oral valacyclovir ( 20 mg / kg / day ) advised for a further 9 days . by september 21 , we measured the serum levels of anti - vzv igg and anti - vzv igm by enzyme - linked immunosorbent assay kits ( enzygnost anti - vzv / igg and enzygnost anti - vzv / igm , dade behring , deerfield , il , usa ) on days 3 and 33 after the appearance of the skin eruption . the values of anti - vzv igg were expressed in international units ( i.e. , miu / ml , with values < 57.0 miu / ml being considered negative ) ; the measurement of anti - vzv igm were expressed as a cut - off index ( i.e. , < 1.0 : negative , 1.02.0 : indeterminate , and > 2.0 : positive ) . serum anti - vzv igg was negative on day 3 and 260 miu / ml on day 33 . the former is considered to play a more important role in the host defense against vzv , since vzv is cell - associated during active infection .   as cord blood contains naive t - cells but no antigen - specific memory t - cells , primary vzv infections by exogenous vzv are expected to occur frequently in cbt recipients .   however , localized herpes zoster is the most frequent clinical presentation in adult patients after cbt . in addition to localized herpes zoster , a rare occurrence of vzv reinfection manifesting as a generalized vesicular eruption without herpes zoster lesions , as was seen in our patient , has been previously observed in patients after cbt . this type of vzv reinfection can be caused by either reactivation of latent virus or exogenous reinfection with vzv . since we did not compare vzv dna between the primary and present infection , it remains unknown whether the infection in our patient was of exogenous or endogenous origin . anti - vzv igg has anti - vzv activity and remains in the body for a long time . considering that our patient had a childhood history of varicella and that the serum anti - vzv igg at day 3 was negative , it appears that humoral immunity against vzv had been lost after cbt , resulting in susceptibility to vzv reinfection . in general , vzv reinfection that appears clinically to be varicella follows a mild clinical course in normal elderly people and immunocompromised hosts . this may be partly explained by the lack of anti - vzv igg at the onset of the skin eruption . however , aisa et al . have reported a case of post - cbt varicella with a relatively severe clinical course despite the presence of a high anti - vzv igg titer . further investigations are necessary to determine why certain post - cbt patients develop varicella , and to clarify why vzv reinfection in post - cbt patients may be more severe than that in normal aged people and immunocompromised patients .