Letters to the Editor
To the Editor:
We read with interest the article of Ohata et al1 comparing the direct immunofluorescence findings of discoid lupus erythematosus (LE) to those of bullous pemphigoid (BP). The authors should be commended on their meticulous characterization of immunoreactant deposition at the epidermal and follicular basement membrane zone (BMZ) in each condition. Putting aside the fact that discoid LE and BP are only rarely in the same clinical or microscopic differential diagnosis, we agree with the general conclusion that direct immunofluorescence (DIF) findings aid differentiation of discoid LE from BP.
In their work, Ohata et al emphasize that the number of positive immunoreactants at the BMZ, whether it be epidermal or follicular, may be instrumental in differentiating discoid LE from BP. However, based on teachings from predecessors2,3 and our clinical observations in a busy immunodermatology laboratory, we believe that the pattern of immunoreactant deposition, in the context of each particular conjugate, should be emphasized in DIF interpretation. Specifically, while we acknowledge that rare cases of BP may demonstrate granular-to-linear deposition of immunoglobulin G (IgG) and complement 3 (C3), the majority of cases show strong linear deposition of C3, typically with strong linear IgG, along the BMZ. However, in DLE, one would expect to see strong granular deposition at the BMZ with IgM and possibly IgG, IgA, and C3 (lupus band). Incidentally, some cases of discoid LE may exhibit a concomitant lichenoid tissue reaction, with scattered and clumped cytoid bodies with immunoglobulins and/or C3, and also shaggy deposition of fibrinogen along the BMZ. We have also observed that cytoid bodies with IgM and IgA may be observed in BP (unpublished observations). Although we agree that follicular BMZ changes may be useful in situations in which overlying epidermal BMZ is unavailable for review,4 the findings in the study of Ohata et al are insufficiently compelling to suggest that follicular BMZ DIF findings would trump changes at the epidermal BMZ.
Ohata et al demonstrated differences in the number of positive immunoreactants on DIF between discoid LE and BP. However, we would emphasize that the interpretation of DIF specimens for immunobullous diseases and LE is more nuanced. Specficially, one must consider the pattern of deposition for each conjugate and the particular combination of conjugates involved when interpreting DIF for BP, LE, and other autoimmune bullous dermatoses.
1. Ohata C, Ohyama B, Nagata H, et al. Comparative study of direct immunofluorescence in discoid lupus erythematosus and bullous pemphigoid. Am J Dermatopathol. 2015. Epub ahead of print.
2. Jordon RE, Triftshauser CT, Schroeter AL. Direct immunofluorescent studies of pemphigus and pemphigoid. Arch Dermatol. 1971;03:486–491.
3. Oliver GF, Winkelmann RK, Muller SA. Lichenoid dermatitis: a clinicopathologic and immunopathologic review of sixty-two cases. J Am Acad Dermatol. 1989;21:284–292.
4. Lehman JS, Camilleri MJ. Diagnostic utility of direct immunofluorescence findings around hair follicles and sweat glands in immunobullous disease. J Cutan Pathol. 2013;40:30–235.