BACKGROUND Grover disease is an entity whose diagnosis is based on clinicopathologic correlation. Histopathologically, focal acantholysis is the most common finding. In some cases, there is prominent squamous atypia which can prove to be very challenging and the lesion may be confused with an epidermal neoplasm. OBJECTIVE To report on atypical histopathological changes in Grover disease and to provide helpful clues to differentiate between the epidermal atypia seen in some cases of Grover disease and epithelial neoplasms. METHODS We analyzed 33 cases of Grover disease histologically diagnosed at Wake Forest Baptist Medical Center, NC, between 2011 and 2017. Atypical changes in keratinocytes were defined as epithelial buds, nuclear pleomorphism, and dyskeratosis in all layers of epidermis or altered granular layer. RESULTS Twenty cases (64%) showed foci with alteration of the normal keratinocytic maturation, whereas 18 cases demonstrated nuclear pleomorphism. Buds of epithelial cells emanating from the basal layer of the epidermis and granular cell alteration was present in 19 cases. CONCLUSIONS The findings especially the presence of an altered granular layer may represent a diagnostic clue in cases of Grover disease with atypical changes.