Differential Diagnosis for Hyperpigmented Lesions on a 2-Year-Old's Hands

Single Most Likely Diagnosis

• Mongolian Spots: These are benign, flat, brown or blue-gray skin markings that are commonly found in infants and toddlers, often on the hands, feet, or back. They tend to fade by the age of 5. Given the age and description, this is a highly plausible diagnosis.

Other Likely Diagnoses

• Café-au-Lait Macules: These are benign, light to dark brown spots that can appear anywhere on the body. They are common in children and may increase in number with age. While they can be isolated, multiple lesions may suggest neurofibromatosis type 1.
• Freckles (Ephelides): Although more common on sun-exposed areas of the face, freckles can appear on the hands, especially after sun exposure. They are benign and tend to darken with sun exposure and lighten without it.
• Melanocytic Nevi (Moles): Moles can appear at any age, including in early childhood. They are usually benign but can be concerning if they exhibit the ABCDE signs of melanoma (asymmetry, border irregularity, color variation, diameter >6mm, evolving).

Do Not Miss Diagnoses

• Congenital Melanocytic Nevus: While rare, these moles are present at birth or appear within the first year. Large or multiple congenital nevi can have a higher risk of developing into melanoma.
• Neurofibromatosis Type 1 (NF1): Characterized by multiple café-au-lait macules, NF1 is a genetic disorder that can lead to tumors forming on nerve tissue. The presence of six or more café-au-lait macules >5mm in prepubertal children or >15mm in postpubertal individuals is one of the diagnostic criteria.
• Peutz-Jeghers Syndrome: This rare genetic disorder is characterized by the development of benign hamartomatous polyps in the gastrointestinal tract and an increased risk of certain cancers. Skin manifestations include melanocytic macules on the lips, oral mucosa, and sometimes the hands.

Rare Diagnoses

• Incontinentia Pigmenti: A rare genetic disorder that affects the skin, hair, teeth, and central nervous system. It is characterized by four stages of skin lesions, including blistering, verrucous, hyperpigmented, and atrophic stages.
• McCune-Albright Syndrome: Characterized by café-au-lait spots, polyostotic fibrous dysplasia, and various endocrine disorders. The skin lesions are typically large and follow the lines of Blaschko.
• Phakomatosis Pigmentovascularis: A rare condition characterized by the combination of vascular and melanocytic nevi, which can be present at birth or appear in early childhood.