Approach to the Problem
Focal red bumps are common in pediatric patients. Etiologies include self-limited, benign diagnoses such as insect bites and erythema toxicum neonatorum; more serious infectious causes like furuncles, carbuncles, abscesses, and cat-scratch disease; and tumors including hemangiomas, pyogenic granulomas, and Spitz nevi.
Key Points in the History
• Erythema toxicum neonatorum is a common, self-resolving rash seen in newborns with onset in the first 24 to 48 hours of life.
• Insect bites may not have a known exposure. Household members may be affected differently, with younger patients experiencing more pronounced local reactions.
• Furuncles, carbuncles, and abscesses are more common in patients and families with a history of recurrent skin infections and/or methicillin-resistant Staphylococcus aureus (MRSA) colonization.
• Hemangiomas typically arise between 2 and 4 weeks of age, but may have a precursor lesion that is sometimes detected at birth.
• Hemangiomas have a phase of rapid growth beginning at 4 to 8 weeks of age and continued expansion through 6 to 9 months of age. This is followed by slowed growth and eventual involution beginning in the second year of life. Hemangiomas typically completely involute by age 7 to 9.
• Pyogenic granulomas tend to grow rapidly and bleed easily. They typically arise later in childhood than hemangiomas.
Key Points in the Physical Examination
• Erythema toxicum neonatorum may appear as isolated lesions that resemble flea bites or as coalescent lesions.
• Insect bites, particularly mosquito bites, tend to have induration that is particularly apparent the day after the insect bite. A central punctum can help to distinguish an insect bite from other swelling.
• A furuncle is a deep bacterial folliculitis. Confluence of several adjacent furuncles can create a carbuncle, which can become further organized into a walled-off abscess. These lesions are all typically tender and warm.
• Although pyogenic granulomas can resemble hemangiomas, only the former exhibit a hypopigmented collarette.
• Stroking a mastocytoma can result in formation of a wheal with swelling and itchiness that occurs within minutes, Darier sign. Patients with mastocytomas may also have dermatographism of unaffected skin.
• The papules associated with cat-scratch disease are oftentimes less pronounced than the accompanying regional lymphadenopathy, which is typically tender and erythematous.
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PHOTOGRAPHS OF SELECTED DIAGNOSES |
Figure 66-1 Insect bite. This insect bite occurred during summer. Note the vesicular reaction. (Courtesy of George A. Datto, III, MD.)
Figure 66-2 Insect bite. Erythematous wheal on dorsum of hand. (Courtesy of George A. Datto, III, MD.)
Figure 66-3 Furuncle. Painful, red nodule with central pustule. (Used with permission from Goodheart HP. Goodheart’s Photoguide of Common Skin Disorders. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2003:126.)
Figure 66-4 Hemangioma on the forearm of an infant with darkly pigmented skin. The lesion appears more purple in color than red. (Courtesy of George A. Datto, III, MD.)
Figure 66-5 Hemangioma. Note the distinct borders and deep red color. (Courtesy of Susan A. Fisher-Owens, MD, MPH.)
Figure 66-6 Involuting hemangioma. Note the central gray discoloration as the hemangioma begins to involute. (Courtesy of Susan A. Fisher-Owens, MD, MPH.)
Figure 66-7 Pyogenic granuloma. Vascular lesion with surrounding collarette. (Courtesy of Kathleen Cronan, MD.)
Figure 66-8 Spitz Nevus. (Used with permission from Stedman’s.)
Figure 66-9 Mastocytoma. (Used with permission from Stedman’s.)
DIFFERENTIAL DIAGNOSIS
Other Diagnoses to Consider
• PHACES syndrome (posterior fossa malformations, hemangiomas, arterial anomalies, cardiac defects, eye anomalies, and sternal clefting)
• Kasabach–Merritt syndrome
• Traumatic hematoma
• Nonaccidental trauma
• Erythema nodosum
• Panniculitis
• Impetigo
• Allergic/contact dermatitis
• Acne
When to Consider Further Evaluation or Treatment
• Patients with recurrent furuncles, carbuncles, or abscesses may benefit from pharmacologic MRSA eradication. These patients may also warrant evaluation for an underlying immunodeficiency.
• Hemangiomas that are near the eye, in the beard distribution, in the diaper area, midline on the scalp, or over the spine should be evaluated by a dermatologist.
• Spitz nevi can resemble melanoma; consider referral to a dermatologist for definitive diagnosis, given the need for prompt treatment of the latter condition.
• Patients with multiple mastocytomas, mastocytosis, or systemic symptoms resulting from manipulation of their lesions should be referred to a dermatologist for further evaluation.
SUGGESTED READINGS
Briley LD, Phillips CM. Cutaneous mastocytoma: a review focusing on the pediatric population. Clin Pediatr. 2008;47:757–761.
Chen TS, Eichenfield LF, Friedlander ST. Infantile hemangiomas: an update on pathogenesis and therapy. Pediatrics. 2013;131:99–108.
Eichenfield LF, Friedan IL, Esterly NB, eds. Neonatal Dermatology. 2nd ed. Philadelphia, PA: Elsevier; 2008:91.
Weston WL, Lane AT, Morelli JG. Color Textbook of Pediatric Dermatology. 4th ed. Philadelphia, PA: Mosby; 2007:73–74, 227, 237–255.