Sucking pads in infancy: A physiologic finding – A case report

Abstract

Sucking pads are benign, self-limiting skin findings that develop on the red lip in infants as a result of repetitive suction and pressure during feeding. Although well described in pediatric dermatology, documentation of these lesions in infants with skin of color is limited, which may cause diagnostic uncertainty. We present a case of a 41-day-old infant with skin phototype V and a 2-week history of progressive fixed darkening and mild scaling of the lips. The mucosal areas were spared and there was no evidence of central cyanosis, clinically consistent with sucking pads. This case highlights the importance of recognizing sucking pads as a cause of lip dyspigmentation in infants across all skin phototypes and understanding normal physiologic variations among diverse populations. Increased representation of pediatric skin of color in educational resources is critical to ensure equitable and accurate clinical assessment.

Introduction

Sucking pads are an example of a benign skin finding in newborns that may cause concern for parents and clinicians if not correctly identified. Sucking pads develop on the red lip in infants due to friction from repetitive suction and pressure during feeding, and indicate the infant has intact motor neuron function.^1,2 Histologically, sucking pads are characterized by a combination of intracellular edema and hyperkeratotic thickening of the lips. ³ Clinically, they are generally self-limited. ² Recognition is important to distinguish these normal findings from pathological lesions and to avoid unnecessary interventions. Although the sucking pads have been described in various pediatric textbooks, there is limited literature or photographic documentation of this phenomenon in infants with skin of color. Here, we report a case of a 41-day-old infant with phototype V skin presenting with sucking pads on both the upper and lower lips.

Case report

A previously healthy, term, 41-day-old infant presented to the Emergency Department due to a 1-week history of cough, intermittent fever, and decreased oral intake. He tested positive for Human Rhinovirus/Enterovirus. The Dermatology service was consulted due to a 2-week history of progressive fixed darkening and mild scaling of the lips, and concerns of cyanosis versus another ominous diagnosis. There was no intraoral, ocular or genital involvement, nor presence of vesicles or bullae. There was otherwise no evidence of central cyanosis, and the patient was maintaining excellent oxygen saturation in the Emergency Department. On physical examination, the baby had phototype V–VI skin and black discoloration of the upper and lower red lip, with mild scale noted (Figure 1). The findings were consistent with sucking pads and were thought to be unrelated to the viral illness. The patient was seen in follow-up in pediatric dermatology 2 months following discharge and was found to have complete resolution of his skin findings (Figure 2), as expected.

Figure 1.

Discoloration of the upper and lower red lip with mild scale.

Figure 2.

Resolution of sucking pads.

Discussion

Sucking pads, also known as sucking calluses, are benign, self-limiting lesions arising from repetitive friction and suction during effective feeding. ² Their recognition is clinically important, as they may mimic more serious mucocutaneous disorders, particularly in infants with darker skin phototypes, where hyperpigmentation may be more pronounced and less well described in Kanada et al. ⁴ On searching the medical literature and then the internet more generally, our team could not find any photographs of sucking pads in patients with skin of color, thus it seemed important to share these photos more broadly to make clinicians aware of this deeply pigmented presentation. The differential diagnosis for lip hyperpigmentation and scaling in infants include infectious etiologies (e.g., herpes simplex, impetigo), acrocyanosis, mucosal hyperpigmentation disorders, or post-inflammatory changes. ⁵ However, the absence of systemic symptoms, the presence of normal oxygen saturation, and the characteristic location and scale support the diagnosis of sucking pads rather than a pathologic entity. The full resolution of findings without intervention serves as additional evidence of this entity’s self-limited nature. ²

Infants with richer phototypes are more likely to experience pigmentary alterations, such as dermal melanocytosis and transitory hyperpigmentation. ⁶ This increased pigmentation is attributed to larger melanosomes that are more dispersed in basal keratinocytes and demonstrate higher activity of melanogenic enzymes. ⁷ Additionally, there is an increased prevalence of melanophages and melanin in the dermis of these individuals. ⁷

This case highlights the importance of including sucking pads in the differential diagnosis of lip discoloration in infants of all skin phototypes. It also emphasizes the necessity of understanding typical physiological variances among various populations. Updates to the curriculum and ongoing research are required to fill in knowledge gaps regarding pediatric skin of color and to optimize outcomes for all infants. Clinicians can provide reassurance to parents when sucking pads are expeditiously recognized and help avoid unnecessary investigations and hospitalizations by recognizing this as a variant of normal.