Grover disease is a clinicopathologic entity characterized by acantholysis. The histologic changes typically occupy circumscribed foci, therefore early stages could go unnoticed and be misdiagnosed.To report on early histopathologic changes in Grover disease.We analyzed 22 cases of Grover disease histologically diagnosed at Wake Forest University School of Medicine, NC, between 2000 and 2009. Early changes were defined as elongation of rete ridges and mild focal acantholysis.Six cases (27%) showed elongation of the rete ridges with focal acantholysis. Mild spongiosis was seen in 4 cases. Superficial perivascular inflammatory infiltrate was found in all cases, 5 of which showed eosinophils.These findings may represent a diagnostic clue in cases of early Grover disease, if clinical correlation is made.