2025 – PAGE 155 – DERMATOLOGY

NEUROFIBROMATOSIS I (NF1)

Neurofibromatosis I (NF1) is an AUTOSOMAL DOMINANT disorder involving the SKIN, BONES, and NERVOUS SYSTEM. Diagnose with at least 2 of the following:

• First-degree relative has the disease
• Neurofibromas
• Lisch Nodules in the iris (they look like mini neurofibromas)
  • IMAGE: www.pbrlinks.com/NF1
• Optic nerve gliomas. This is the neurologic component.
• 6 REGULAR café-au-lait macules. As they get older, the SIZE DOES MATTER. If prepubertal, these are > 5 mm, if postpubertal, > 15 mm. Ten years of age is a good cutoff. These macules can be present at birth. Children can have an increase in the size and number as they age. Therefore, it is very important that they have regular follow-up, especially if there is a family history of the disorder. As a side note, children can also get pheochromocytomas or renal artery stenosis, so the BP should be monitored regularly.
• Scoliosis or bony abnormalities
• Axillary or inguinal freckling
• MNEMONIC: (FOR NF-1) SKIN + “ORTHO” + NEURO issues = S.O.N. This is NF ONE, SON (or daughter!)!!!

NEUROFIBROMATOSIS 2 (NF2)

(Low-yield topic). Neurofibromatosis 2 (NF2) findings include nonmalignant tumors of the nervous system, especially acoustic nerve tumors (AKA neuromas or schwannomas). These can cause tinnitus or even hearing loss. Patients can also have eye tumors, cataracts, retinal problems, spinal cord tumors, and meningiomas. Look for a family history.

PEARL: Tuberous Sclerosis and Neurofibromatosis are both AUTOSOMAL DOMINANT, BUT they both have a HIGH RATE OF NEW MUTATIONS. Do not exclude these from your differential if they mention that the patient’s parents do not have the disorder.

INCONTINENTIA PIGMENTI

Incontinentia pigmenti is a severe X-linked DOMINANT disease that results in DEATH for all MALES before birth. If presented with this as an answer choice in a living patient, make sure the vignette refers to a FEMALE patient. There are four stages of this disorder. It starts with the inflammatory vesicular phase, followed by a verrucous phase, followed by the hyperpigmentation phase noted along the lines of Blaschko, and finally followed by a phase in which the hyperpigmentation disappears. This can leave atrophy or hypopigmentation behind.

SYSTEMIC ASSOCIATIONS: DELAYED DENTITION, intellectual disability, paralysis, PEG teeth, and seizures.

IMAGE: www.pbrlinks.com/INCONTINENTIA1
IMAGE: www.pbrlinks.com/INCONTINENTIA2
IMAGE: www.pbrlinks.com/INCONTINENTIA3
IMAGE: www.pbrlinks.com/INCONTINENTIA4

MNEMONIC: As WOMEN age, they tend to have more “INCONTINENTs.” Incontinentia = Female patient. Imagine a WOMAN on the ground having a SEIZURE. She becomes INCONTINENT of urine, which streams down her PEG legs and creates black-and-white LINEAR SKIN LESIONS. PEG refers to PEG TEETH.