What Explains This Newborn’s Palmar Rash?
A 3-week-old, full-term boy born via spontaneous vaginal delivery presented with a 1-day history of a vesiculopustular rash on his right palm. The patient’s mother reported no change in behavior or other signs of illness in the newborn. The patient had been breastfeeding well and was stooling and urinating appropriately. He had no history of fever.
The birth history was notable for 7 days of treatment with ampicillin and gentamicin for presumed sepsis secondary to hypoglycemia after birth and insufficient prophylaxis in a group B streptococci culture–positive mother. Blood cultures from this sepsis workup were negative. Prenatal laboratory test results were otherwise negative for infection. There were no recent infectious exposures, no family history of a similar rash or other symptoms, and no maternal history of oral or genital lesions.
On physical examination, approximately 15 vesiculopustular papules of 1 to 3 mm in diameter were noted over the palm of the right hand (Figure). No lesions were noted anywhere else on the newborn’s body. His vital signs were normal, and he was afebrile. The patient was found to have a C-reactive protein level of 1.0 mg/L. Results of a complete blood count were within normal limits, with a white blood count of 6,700/µL. Results of direct fluorescent antibody testing from the bases of 2 of the skin lesions were negative for herpes simplex virus.
What is the cause of these lesions?
(Answer and discussion on next page)
Answer: Acropustulosis of infancy
The rash is consistent with acropustulosis of infancy, an uncommon but not rare benign chronic skin eruption.
Acropustulosis lesions begin as small macules or papules that progress to form distinct vesicles and pustules. The vesiculopustular lesions typically measure 1 to 3 mm in size, are located on the palms and/or soles, and sometimes involve other areas.1
The lesions usually present between 2 and 12 months of age but can present around the time of birth. Flares often last between 5 and 14 days then resolve spontaneously. The course can be chronic and remitting in the first 2 to 3 years of life, with flares occurring up to every 2 to 4 weeks. Each subsequent flare tends to decrease in severity and duration, and the condition typically resolves completely with no further flares after 3 years of age.2
Lesions can be intensely pruritic and may heal with macular hyperpigmentation. No other organ systems are involved. The cause of acropustulosis of infancy is unknown; however, in some cases there may be an association with a preceding scabies infection.3
The differential diagnosis for infantile acropustulosis includes erythema toxicum neonatorum (ETN), transient neonatal pustular melanosis, scabies, and, less commonly, dyshidrotic eczema, pustular psoriasis, chickenpox, fire ant bites, hand-foot-and-mouth disease, and impetigo.1 No laboratory tests are needed, and the diagnosis typically is made clinically. Biopsy usually is not required but if done shows a subcorneal pustule filled with polymorphonuclear neutrophils and eosinophils.3
Acropustulosis can be differentiated from the much more common ETN by the timing and appearance of lesions. Unlike acropustulosis, ETN usually presents at 2 to 3 days of life and resolves within the first 2 weeks. The pustules of ETN often are preceded and accompanied by a marked erythematous base, which is not a defining characteristic of acropustulosis lesions. ETN’s distribution spares the palms and soles, and biopsy results show predominantly eosinophils.1
Acropustulosis of infancy is self-limited and therefore treatment often is unnecessary. If treatment is warranted, the first-line option is mid- to high-potency topical corticosteroids. Other reported treatments include oral erythromycin, oral antihistamines, and oral dapsone. Pruritus can be controlled with a topical anesthetic (eg, pramoxine) or oral antihistamines. Emollients can be used for maintenance between breakouts. The prognosis is excellent.1
Our patient’s lesions resolved without intervention and have not recurred.
1.Cutaneous disorders of the newborn. In: Paller AS, Mancini AJ. Hurwitz Clinical Pediatric Dermatology: A Textbook of Skin Disorders of Childhood and Adolescence. 4th ed. Philadelphia, PA: Elsevier Saunders; 2011:10-36.
2.Paloni G, Berti I, Cutrone M. Acropustulosis of infancy. Arch Dis Child Fetal Neonatal Ed. 2013;98(4):F340.
3.Neonatal dermatology. In: Cohen BA. Pediatric Dermatology. 4th ed. Philadelphia, PA: Elsevier Saunders; 2013:chap 2.
Mr Powers is a fourth-year medical student at the University of Florida College of Medicine in Gainesville. Dr Riley is a pediatric resident and Dr Ritchie is a pediatric hospitalist in the Department of Pediatrics at the UF Health Shands Children’s Hospital in Gainesville, Florida.
Kirk Barber, MD, FRCPC––Series Editor:Dr Barber is a consultant dermatologist at Alberta Children’s Hospital and clinical associate professor of medicine and community health sciences at the University of Calgary in Alberta.