Authors' reply.

Sir,

We thank you for your great interest in our article.[1] We agree with your view that immunofluorescence pattern is very important in making a diagnosis of linear IgA disease (LAD) in both children and adults. There is no problem in labeling cases with typical linear deposition of IgA at the basement membrane zone (BMZ) as LAD. However, confusion arises when cases have a characteristic ‘cluster of jewels appearance’ or ‘string of pearls appearance’ of lesions but show predominant deposition of other immunoglobulins than IgA at BMZ. Ignoring this important clinical sign, especially among childhood cases, and basing diagnosis on immunofluorescence only would mean that we could potentially under diagnose many cases of chronic bullous disease of childhood.[2] Labeling such cases as LAD despite immunofluorescence not showing predominant IgA will make it a misnomer. Numerous such cases have been reported with a multitude of terms like mixed immunobullous disease, linear IgG/IgA disease, linear IgA/IgG disease, and so on, without having much difference from the classical ‘chronic bullous disease of childhood’ in therapeutic response to dapsone or prognosis.[3] Hence an umbrella term deeply entrenched in the dermatological literature, like ‘chronic bullous disease of childhood’, may be preferred.

The term ‘chronic’ in the nomenclature of this entity is not completely misplaced as the condition usually lasts for as long as 3-8 years and several cases persisting well into adulthood have been reported.[4] However, we agree with your concern that this term may cause anxiety for the patients or their parents.

Peterson et al. described a case of linear IgA bullous disease but initially presenting with histopathologic and immunofluorescent findings consistent with bullous pemphigoid.[5] Initial direct immunofluorescence showed a predominance of linear IgG at the basement membrane zone (BMZ) of perilesional skin, and indirect immunofluorescence showed a low titer circulating IgG anti-BMZ antibody. Repeat studies 3 years later revealed a predominance of linear IgA immune deposits at the BMZ and no circulating anti-BMZ antibody. Further, immunoelectron microscopy and other studies confirmed the diagnosis of LAD. Patient responded well to dapsone. This case demonstrates that direct or even indirect immunofluorescent findings, when considered alone without clinical correlation, can be misleading.