Repeatability of clinico-histopathological findings and direct immunofluorescence of fixed, paraffin embedded specimens for diagnosis of lichen planus

Lichen planus (LP) is a chronic mucocutaneous disorder mediated by the impaired immunity, in which the concomitance of clinical and histopathological findings are necessary for a definite diagnosis. In case of discrepancy between clinical and histopathological findings, use of adjunct diagnostic methods such as direct immunofluorescence (DIF) is recommended. This study sought to assess the repeatability of clinico-histopathological findings and direct immunofluorescence of fixed, paraffin embedded specimens for diagnosis of LP. In this retrospective descriptive study, 49 oral and cutaneous LP specimens were subjected to DIF assessment using fibrinogen, C3 and IgM. The intensity of fluorescence staining was graded as 0, 1 or 2. Findings were compared in each group and between oral and cutaneous LP groups using statistical tests. Statistical analyses revealed a correlation between C3 and IgM expression (Spearman’s rho: 0.697, p=0.000), which was more prominent in cutaneous specimens (p=0.000). Additionally, a correlation was observed between fibrinogen and IgM expression in oral LP (Spearman’s rho: 0.764, p=0.02). It seems that DIF assessment of formalin-fixed, paraffin embedded specimens using C3, fibrinogen and IgM does not have adequate repeatability for clinico-histopathological findings; although, combined application of C3 and IgM in cutaneous and IgM and fibrinogen in oral LP specimens showed higher repeatability.