BALLOONlNG (It. ballone "large ball," ME -ing "to become like")

"Intracellular edema" of epidermis and epithelial structures of adnexa, recognizable morphologically as swollen pale cytoplasm of affected spinous cells (Fig. 3.17). Rupture of markedly ballooned keratinocyles leads to formation of a pattern of epidermis that resembles a net and, therefore, is termed reticular alteration. When ballooning of keratinocytes is marked, as when reticular alteration has developed, necrosis of them is invariable and is characteristic of infections by some viruses, such as herpesvirus, poxvirus, and Coxsackievirus, but also of noninfectious diseases such as erythema multiforme, fixed drug eruption, and MuchaHabermann disease. The term ballooning, if unmodified, is enigmatic because ballooning describes other changes in other types of cells, such as ballooned melanocytes of nevi and melanomas (balloon cell nevi and balloon cell melanoma).