When evaluating lumps and bumps in infants, categorizing them can help determine whether they need immediate attention, said James R. Treat, MD, a pediatric dermatologist at Children’s Hospital of Philadelphia, Pennsylvania.

For example, Spitz nevi occur in patients younger than 20 years, most often on the face and lower extremities, but most are benign, Dr. Treat said. However, he recommends a biopsy if the patient is pubertal or older, or if the lesions are larger than 8 mm, amelanotic, or show asymmetry, ulceration, or excessive growth.

By contrast, neurocutaneous melanosis is a rare but serious skin condition that occurs in children and can be fatal if it progresses to melanoma, he pointed out. The condition involves the migration of melanocytes into the spinal canal and cerebrospinal fluid during development. Symptoms may include headache, seizures, and paralysis, and clinicians should keep them in mind when seeing children with melanocytic nevi, he noted. The highest risk for melanoma transformation is increased for individuals with more than 20 congenital moles, and “the second-highest risk is having a giant nevus lying overtop of the midline spine or scalp,” he said.

In some cases, yellow or tan lesions in children are benign and will resolve on their own, Dr. Treat said.

Juvenile xanthogranuloma (JXG), characterized by yellow-brown asymptomatic papules and nodules, develops most often within the first year of life, but the lesions usually resolve spontaneously by school age, he added.

Mastocytosis, localized collections of mast cells, presents as yellow/tan lesions that develop within the first 2 years of life. The condition can be systemic; patients may experience flushing and diarrhea because of localized release of histamines, and those with a history of weight loss, easy bruising or bleeding, hepatosplenomegaly, or lymphadenopathy may have systemic disease, Dr. Treat explained.

Subcutaneous fat necrosis can present within the first 2 weeks of life as firm, red-purple tender nodules that may be disturbing to parents. These lesions are most likely to appear on the cheeks, arms, back, and thighs, and are related to hypoxia or trauma, he added. The lesions usually resolve spontaneously within a period of weeks to months, although they may heal with some atrophy and scarring, he said. Subcutaneous fat necrosis is associated with hypercalcemia, so “it is important to check frequently, as hypercalcemia can occur weeks after the nodules resolve,” he commented.

Dr. Treat disclosed serving as a consultant to Procter & Gamble. SDEF and this news organization are owned by Frontline Medical Communications.