Diagnostic Approach to Small Skin Lesions in Children

Introduction to Diagnostic Considerations

The American Academy of Pediatrics recommends considering the age of onset, anatomical distribution, and presence of Darier's sign to distinguish between mastocytosis, infantile hemangioma, and inflammatory dermatoses like atopic eczema 1.

The presence of skin lesions before 6 months suggests mastocytosis or congenital eczema, according to the American Academy of Pediatrics 1.
Lesions appearing before 4 weeks are indicative of infantile hemangioma, with maximum growth completed by 5 months, as noted by the American Academy of Pediatrics 2, 3.
The distribution of lesions on the trunk and extremities is typical of mastocytosis (urticaria pigmentosa), as described by the American Journal of Clinical Dermatology 6, 4, 1.
Flexural areas are characteristic of atopic eczema, according to the American Academy of Pediatrics 1.

Mastocytosis cutaneous presents with red-brown to yellow lesions, multiple macules, plaques, or nodules, and a positive Darier's sign, as described by the American Journal of Clinical Dermatology 6, 5, 1.
Infantile hemangioma appears before 4 weeks, with superficial, deep, or mixed forms, and may be associated with PHACE or LUMBAR syndromes, as noted by the American Academy of Pediatrics 2, 3.
Atopic eczema is diagnosed based on pruritus and at least three of the following: flexural involvement, personal or family history of atopy, dry skin, or visible eczema, according to the American Academy of Pediatrics 1.

For mastocytosis, evaluate for flushing, pruritus, abdominal pain, diarrhea, hypotension, and respiratory symptoms, as described by the American Journal of Clinical Dermatology 7, 5, 1.
Emergency signs include flushing, dyspnea, wheezing, nausea, vomiting, diarrhea, and hypotension, as noted by the American Journal of Clinical Dermatology 8.

Determine the age of onset: < 6 months suggests mastocytosis or congenital eczema, according to the American Academy of Pediatrics 1.
Identify the distribution: trunk/extremities (mastocytosis) vs flexions (eczema), as described by the American Academy of Pediatrics 1.
Test for Darier's sign: positive = highly probable mastocytosis, as noted by the American Journal of Clinical Dermatology 5, 7, 1.
Evaluate pruritus: obligatory for atopic eczema, according to the American Academy of Pediatrics 1.
Investigate for complications: ulceration, functional impairment, systemic symptoms, as described by the American Journal of Clinical Dermatology and the American Academy of Pediatrics 8, 2, 3, 1.