[D-penicillamine-induced pemphigus: changes in anti-32-2B immunostaining patterns].

BACKGROUND: It has been reported that D-penicillamine causes pemphigus that is typically superficial. Immunostaining with monoclonal anti-32-2B antibody targeting desmoglein 1 and 3 can help differentiate between drug-induced and classical auto-immune pemphigus. Absence of specific staining militates in favour of drug-induced pemphigus whilst positive staining suggests an auto-immune aetiology that is ongoing despite discontinuation of drug therapy.

PATIENTS AND METHODS: A 59-year-old male patient was referred for management of superficial pemphigus 1 year after starting D-penicillamine treatment for scleroderma. The diagnosis of pemphigus was confirmed histologically (intra-epidermal cleavage, acantholysis and perikeratinocytes, deposition of IgG and complement C3). Immunochemical staining with anti-32-2B antibody was initially normal, in keeping with drug-induced pemphigus. Despite discontinuation of D-penicillamine, pemphigus recurred in 2008. A further skin biopsy was undertaken and anti-32-2B staining was abnormal, which is consistent with auto-immune pemphigus.

DISCUSSION: Numerous cases of drug-induced pemphigus have been described in the literature. In approximately half of all cases, the pemphigus recedes after cessation of the causative drug. However, there have been no previous reports that changes over time in the immunostaining with anti-32-2B antibodies can mirror a change in form of pemphigus from a drug-induced type to an idiopathic type as well as the associated clinical feature of persistence after drug withdrawal.

CONCLUSION: Normal staining with anti-32-2B antibody is associated with a favourable prognosis as regards resolution of drug-induced pemphigus. When, as in this case, status changes to abnormal staining, there is a risk that the pemphigus may become chronic despite discontinuation of therapy.