Differential Diagnosis
The patient's presentation of light brown hyperpigmented lesions over the trunk and extremities, along with freckle-like lesions over both axillae, suggests a neurocutaneous syndrome. The most likely diagnosis is Neurofibromatosis Type 1 (NF1), given the description of the skin lesions, which are consistent with café-au-lait macules, a hallmark of NF1.
Single most likely diagnosis
- Neurofibromatosis Type 1 (NF1): The presence of multiple café-au-lait macules and freckling in the axillary regions is highly suggestive of NF1. NF1 is associated with an increased risk of various tumors, including optic nerve gliomas.
Other Likely diagnoses
- Neurofibromatosis Type 2 (NF2): Although less likely given the specific findings, NF2 could be considered if there were symptoms or signs suggestive of vestibular schwannomas or other NF2-related tumors. However, the skin findings described are more typical of NF1.
- Legius Syndrome: This is a condition that can present with café-au-lait macules similar to NF1 but typically lacks the other features such as neurofibromas and optic gliomas. It's caused by mutations in the SPRED1 gene.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Malignant Peripheral Nerve Sheath Tumors (MPNSTs): While not a diagnosis per se, it's a complication of NF1 that can be life-threatening. Patients with NF1 are at increased risk of developing MPNSTs, which can arise from neurofibromas.
- Optic Pathway Gliomas: These are tumors of the optic nerve or its pathways and are more common in children with NF1. They can lead to significant morbidity, including vision loss.
Rare diagnoses
- McCune-Albright Syndrome: Characterized by café-au-lait spots, polyostotic fibrous dysplasia, and various endocrine disorders. The absence of other systemic symptoms makes this less likely.
- Multiple Café-au-Lait Spots Syndrome: A condition with multiple café-au-lait macules without other features of neurofibromatosis. This diagnosis would be considered if the patient did not meet the full criteria for NF1 or other syndromes.
Given the information provided, the patient is at an increased risk for Optic Nerve Glioma (E), which is a common complication in NF1 patients. This condition can lead to significant morbidity, including vision loss, and thus represents a critical consideration in the management and follow-up of patients with suspected NF1.