Abstract
Background: Reliable histopathologic or immunohistochemical findings to distinguish cutaneous graft-versus-host disease (GVHD) from morbilliform drug or viral exanthems are lacking.
Methods: This was a single-center retrospective case series including 25 patients with GVHD (31 specimens) and 26 patients with drug or viral exanthems (27 specimens). Hematoxylin and eosin-stained slides were examined, and all cases were stained for CD56 to assess for the presence of CD56⁺ natural killer (NK) cells. Mean differences for continuous variables (defined as GVHD−drug/viral) and odds ratios (ORs) for binary outcomes were estimated using generalized estimating equations.
Results: Hyperkeratosis was more common in GVHD than drug/viral exanthems (87% vs 11%; OR 54.0, 95% CI 24.51–119; p<0.0001), whereas parakeratosis did not differ significantly (13% vs 7%; OR 1.85 (0.89–3.87); p=0.101). Adnexal vacuolar interface change was more common in GVHD (81% vs 7%; OR 52.08 (23.71–114.4); p<0.0001). Extravasated erythrocytes were less frequently present in GVHD (35% vs 63%; OR 0.32 (0.21–0.49); p<0.0001). GVHD showed fewer eosinophils (mean difference -3.08 per high-power field (HPF) (-4.08 to -2.07); p<0.0001). In GVHD, CD56+ cells represented a higher proportion of the global inflammatory infiltrate (+11.6% (6.5–16.7); p<0.0001), and greater numbers of CD56+ cells were present in the dermis (+4.11 per HPF (1.43–6.79); p=0.003) and epidermis (+2.12 per HPF (1.45–2.78); p<0.0001).
Conclusions: Compared with drug or viral exanthems, GVHD more often shows hyperkeratosis and adnexal vacuolar interface change, as well as fewer eosinophils and fewer extravasated erythrocytes. GVHD demonstrates increased numbers of CD56⁺ NK cells, suggesting CD56 immunostaining may be a useful adjunct to diagnosis.
