What is the most likely diagnosis for a 6-year-old boy presenting with right lower extremity weakness, worsening headaches, abdominal pain, dark urine, weight loss, palpable abdominal mass, left costovertebral angle tenderness, decreased strength of the right lower limb, and angiofibromas around the nose and cheeks, with a history of infantile seizures?

Differential Diagnosis

The patient's presentation is complex, involving neurological, abdominal, and dermatological symptoms. Here's a categorized differential diagnosis:

• Single most likely diagnosis

  • Tuberous Sclerosis Complex (TSC): This diagnosis is strongly suggested by the presence of angiofibromas (adenoma sebaceum), which are pathognomonic for TSC, along with a history of infantile seizures, and the potential for subependymal giant cell astrocytomas (SEGAs) that could explain the worsening headaches and neurological symptoms. The abdominal mass could be related to renal angiomyolipomas, which are common in TSC.

• Other Likely diagnoses

  • Neurofibromatosis Type 1 (NF1): Although less likely given the specific constellation of symptoms, NF1 could explain some findings like neurofibromas potentially causing nerve compression leading to weakness, and optic gliomas could lead to vision problems and headaches. However, the presence of angiofibromas and the specific pattern of symptoms make TSC more likely.
  • Von Hippel-Lindau Disease (VHL): This condition could explain some symptoms like abdominal masses (renal cell carcinoma or cysts) and neurological symptoms if there are hemangioblastomas in the central nervous system. However, the dermatological findings and infantile seizures are not typical for VHL.

• Do Not Miss

  • Wilms Tumor: Given the abdominal mass and costovertebral angle tenderness, Wilms tumor must be considered, especially in a child. It's a common abdominal tumor in children that can present with an abdominal mass and systemic symptoms like weight loss and abdominal pain.
  • Neuroblastoma: Another abdominal tumor that could explain the mass, weight loss, and potentially the neurological symptoms if there's metastasis or paraneoplastic syndrome.

• Rare diagnoses

  • Sturge-Weber Syndrome: Characterized by a port-wine stain, this condition could explain some neurological symptoms and the presence of a port-wine stain (option A), but it doesn't account for the abdominal mass or the angiofibromas.
  • Pheochromocytoma: Part of the differential for abdominal masses and systemic symptoms like weight loss and hypertension, but it's rare in children and doesn't explain the dermatological or most neurological findings (option B).
  • Lisch Nodules and Vestibular Schwannoma: These are associated with Neurofibromatosis Type 2 (NF2), which could explain some neurological symptoms but doesn't fit well with the overall clinical picture presented, especially the angiofibromas and abdominal findings (options C and E).