12 Infectious Diseases Identified by Their Characteristic Rashes

6. Hand, Foot, and Mouth Disease - The Acral Distribution

Hand, foot, and mouth disease (HFMD), most commonly caused by coxsackievirus A16 and enterovirus 71, presents with a characteristic distribution pattern that gives the disease its descriptive name. The condition typically begins with fever, malaise, and sore throat, followed by the development of painful vesicular lesions in the oral cavity, particularly on the tongue, gums, and buccal mucosa. These oral lesions often ulcerate quickly, causing significant discomfort and difficulty eating or drinking. Simultaneously or shortly after the oral lesions appear, characteristic vesicles develop on the palms, soles, and sometimes the dorsal aspects of the hands and feet. These cutaneous lesions are typically oval-shaped, gray-white vesicles surrounded by erythematous halos and are pathognomonic for HFMD when found in the classic distribution. The vesicles on the hands and feet are usually painless, unlike the oral lesions, and may be accompanied by similar lesions on the buttocks and genital area, particularly in younger children. The acral distribution pattern is unique among common viral exanthems and makes HFMD readily distinguishable from other vesicular diseases. In recent years, atypical presentations have been observed, particularly with certain enterovirus strains, where the rash may extend beyond the classic sites to include the arms, legs, and trunk. The disease is typically self-limited, with lesions resolving within seven to ten days, though some children may experience nail changes, including onychomadesis (nail shedding), several weeks after the acute illness.