A Study of Epidermal Elafin Immunohistochemistry as a Diagnostic Biomarker of Acute Skin GVHD

Abstract Background: Acute skin graft-versus-host disease (GVHD) is a common and early complication of haematopoietic stem cell transplantation (HSCT). Diagnosing GVHD through histopathology alone can be challenging due to overlap with other conditions. Tissue elafin immunohistochemistry (IHC) has shown potential as a diagnostic tool, but studies report conflicting results. Objectives: To examine the utility of elafin IHC in skin biopsies for accurate acute skin GVHD diagnosis in HSCT recipients. Methods: Consecutive allogenic HSCT recipients in a tertiary care centre in South India, who developed rash within the first 100 days post-HSCT during a 17-month period were recruited. Skin biopsies were taken on the day of rash and epidermal elafin IHC was done. Staining of >50% of the epidermis was considered positive. The final diagnosis of skin GVHD was assigned using a composite criteria of clinical features, histopathology and response to treatment. We evaluated the accuracy of elafin IHC in GVHD diagnosis. Results: Sixty-eight skin biopsies from 58 patients (median age 14 years; range 1–53; 46 males) were analyzed. Median day of rash onset was 23.5 (range: 5–98). GVHD was confirmed in 45 (66.2%) episodes. Elafin IHC was positive in all GVHD and 9/23 non-GVHD cases, six of which were engraftment syndrome. The sensitivity and specificity of elafin IHC were 100% and 58.3%, respectively. There was a significant correlation between positive elafin IHC and GVHD ( P < 0.0001). Conclusion: Tissue elafin is a highly sensitive IHC marker for diagnosis of acute skin GVHD, including cases without classic histopathological findings. However, its utility is limited in distinguishing GVHD from engraftment syndrome.