Medical Etymology: Tales Behind the Terms is a series of articles discussing the stories, origins, and meanings of words we use every day in medicine. The goal is to explore the history of the complex jargon we use with patients and learners. In doing so, I hope that we, as physicians-in-training, can deliver better healthcare that is understandable and memorable for all.
Newborn skin rashes are incredibly common, and while some may appear concerning, most are benign and self-resolving. The term “rash” has several possible origins: the Old French “rasser” (to scrape), the Latin “rasitare” (scraped), or the Middle English “rasch” (to scrape or scratch). It likely has etymological connections to the modern word “razor,” a tool used for shaving, which, if used improperly, can often lead to a rash. While babies are unlikely to suffer from razor burns, there are several distinct rashes that may arise during the newborn period.
The most common rash seen in newborns is Erythema Toxicum Neonatorum. It appears as small red bumps and flat spots that may evolve into raised pustules. These “pustules,” small inflammatory bumps filled with pus, are surrounded by a patch of redness. The exact cause is not entirely clear, but it may be due to the infant’s innate immune system responding to friendly microbes colonizing the skin for the first time. Given the benign etiology and natural resolution, the terms “erythema” (red) + “toxicum” (toxin) + “neonatorum” (of the newborn) should not seem so alarming; the term “toxicum” historically described the rash’s dramatic appearance, which was once thought to be harmful.
Transient Neonatal Pustular Melanosis is a rash with “vesicles” (from the Latin, “vesicula”, meaning “small bladder” or “little sac”) that rupture easily, leaving scales and pigmented spots that fade over several weeks. The term explains the description perfectly: “transient” (from Latin “transiens”, meaning “temporary”, something that can “go across”) + “neonatal” (from “neo-”, new, and “natus”, born) + “pustular” (blister, pimple) + “melanosis” (from Greek, “melas”, meaning “black” or “dark”). Knowing this, one can easily explain to a concerned parent that this is a rash in newborns consisting of small pimples that, when ruptured, temporarily leave dark or discolored patches on the skin.
Acne Neonatorum appears similar to the acne seen in adolescents and adults, with closed “comedones” on the forehead, nose, and cheeks, among other places. “Comedone” comes from the Latin “comedo”, meaning “glutton” or “eater,” because the material within these comedones was once thought to be parasitic worms or grubs that “ate” away at the skin6. The term “acne” comes from the Greek “akme”, meaning “highest point” or “peak,” referring to the “tips” of the skin eruptions. Thus, “acne neonatorum” is simply acne in the newborn, caused by stimulation of the oil glands by maternal or infant hormones. As the hormone system calms down after birth, so does the acne – at least until puberty, when the hormone system begins to roar yet again, and the “peaks” of this skin eruption may re-emerge.
Milia are very small white or yellow “papules” (bumps) that often appear on the forehead and nose. They are due to retained “keratin” (“horn” or “horny”), a substance found in hard, “horny” tissues such as hair, nails, and the outer layer of skin. The term “milia” comes from the Latin “milium”, a grain of the millet plant, which appears small and round. Another rash with a similar name but a different etiology is “miliaria”, caused by the retention of sweat due to partial closure of glandular structures. The appearance of “miliaria” is like that of milia, hence the similarity in name. If the sweat gland obstruction occurs at a deeper level, the rash may appear redder and is thus called “miliaria rubra” (“rubra” being Latin for “red”). More commonly, this is known as “heat rash.”
Seborrheic Dermatitis is a common condition in newborns that typically appears as red, scaly patches, often found on the scalp, face, or behind the ears. The term “seborrheic” comes from “sebum”, the oily substance produced by sebaceous glands, combined with “-rrhea”, meaning flow or discharge. “Dermatitis” derives from “dermis” (skin) and “-itis” (inflammation), reflecting the fact that the rash often occurs in areas of the skin where sebaceous glands are active. The condition is thought to be triggered by an overproduction of sebum or an inflammatory response to yeast naturally present on the skin. Although it may appear alarming due to its crusted, yellowish appearance, seborrheic dermatitis is generally harmless and tends to resolve on its own over time. The condition is sometimes referred to as “cradle cap” when it affects the scalp, as the patches of skin can become thickened and crusty, but it is not a serious skin disorder.
While the rashes described above are mostly benign and transient, one serious, though rare, neonatal skin disorder is Neonatal Pemphigus. This blistering condition appears as painful, fluid-filled blisters and erosions on the skin. The term “pemphigus” comes from the Greek word “pemphix”, meaning “bubble” or “blister,” which aptly describes the appearance of the blisters that form in this condition. Being an autoimmune disorder, neonatal pemphigus may require immunosuppressive therapy, along with topical treatments.
Though not technically skin rashes, two transient skin changes due to newborn vascular physiology are worth noting. “Cutis Marmorata” is the appearance of marbled or mottled skin1, which can be understood as “cutis” (skin) + “marmorata” (from the Latin “marmor”, meaning marble). Thus, it translates to “marbled skin” and accurately describes the lace-like pattern caused by transient blood vessel constriction and dilation. “Harlequin Color Change” describes a pattern of redness, or erythema, that occurs when a newborn lies on their side, while the opposite side remains pale. This results in a sharp line of demarcation due to immature regulation of blood flow. The term “Harlequin” comes from the French “arlequin”, a character in comedic Italian art known for wearing a patchwork costume of contrasting colors. One can compare the patchwork-dressed character to the patchwork of redness and paleness in an infant with this condition. Both phenomena are transient and resolve as the baby’s body matures.
Newborns are beautiful, fascinating creatures, though they often present with one of the rashes described above. Thankfully, most of these are temporary and harmless, and having a thorough understanding of their names and clinical courses allows students and providers to accurately describe the condition to worried parents. The many different neonatal rashes provide great examples of how important it is not just to memorize a disease’s name, but to truly learn the tale behind the term.
Contributing Writer
University of Texas Southwestern Medical Center
Benjamin is a first-year family medicine resident in Fort Worth, Texas. In 2021, he graduated from UT Austin (Hook 'Em!) with a Bachelor of Science in Neuroscience and Bachelor of Science and Arts in Biology. In his free time, he enjoys running, reading, medical etymology and all things outdoors. After graduating residency, Benjamin would like to pursue a career in rural Family Medicine, with an additional year of training in Obstetrics.
