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What is Lisch nodules (Pigmented Iris hamartomas) are seen in and explain in detail?
Ans. b (Neurofibromatosis) (Ref. Harrison's Internal Medicine 17th ed., Chapter 374; RRM 7th ed., p.316)# Lisch nodules (iris hamartoma) and Optic gliomas = NF-1.# Glaucoma = Sturge Weber syndome.# Retinal angiomas = VHL# GlaucomaNEUROFIBROMATOSIS# Autosomal dominant inherited disorder- pure neurofibromas (= tumor of nerve sheath with involvement of nerve, nerve fibers run through mass)- neurilemmomas (= nerve fibers diverge and course over the surface of the tumor mass)(a) localized neurofibroma (most common, 90%)(b) diffuse neurofibroma (mostly solitary + not associated with NF1)(c) plexiform neurofibroma (PATHOGNOMONIC of NF1)Peripheral Neurofibromatosis (90%) = NEUROFIBROMATOSIS TYPE 1 = von Recklinghausen disease# autosomal dominant with abnormalities localized to the pericentromeric region of chromosome 17.- CLASSIC TRIAD:- Cutaneous lesions- Skeletal deformity- CNS manifestations# CNS and ocular MANIFESTATIONS- Lisch nodules= melanocytic iris hamartomas <2 mm in size- Optic pathway glioma- Hydrocephalus (Aqueductal stenosis)- Vascular dysplasia= occlusion / stenosis of distal ICA, proximal MCA/ACA- Plexiform neurofibromas are PATHOGNOMONIC for NF1- Erosion of bony elements with marked posterior scalloping# SKELETAL MANIFESTATIONS (in 25-40%)- Harlequin appearance to orbit (empty orbit) = partial absence of greater and lesser wing of sphenoid + orbital plate of frontal bone- Sharply angled focal kyphoscoliosis (50%) in lower thoracic + lumbar spine- Pseudarthrosis after bowing fracture (particularly in tibia) in 1st year of life# Others:- Cafe-au-lait spots= pigmented cutaneous macules >6 in number, >5 mm in greatest diameter; Coast of California.; Freckling.- Progressive pulmonary interstitial fibrosis with lower lung field predominance (up to 20%)- Pheochromocytoma- Renal artery stenosis: very proximal- Malignant peripheral nerve sheath tumor - most common malignant abdominal tumor in NF1