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Presented by Ralph Hruban, M.D. and prepared by Lynette S. Nichols, M.D.
Case 2: This patient had numerous pigmented skin lesions and a subcutaneous nodule.
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Question 1 of 1
1. Question
Week 137: Case 2
This patient had numerous pigmented skin lesions and a subcutaneous nodule. The nodule was resected./images/Lyn’s/h2a.jpg
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/images/Lyn’s/h2d.jpgCorrect
Answer: Plexiform neurofibroma
Histology: In contrast to this first case in which the tumor arose from the surface of the nerve, this neoplasm clearly involves the nerve itself. In fact, a plexus, or group of nerves is involved.
Discussion: This case was also put on conference, not because it is difficult, but because it is such a distinctive example. As noted above, the neoplasm involves a plexus of nerves. The neoplastic cells have serpentine (snake-like) thin nuclei. The interstitium shows “shredded carrots” like collagen and numerous mast cells. These are all of the classical features of a plexiform neurofibroma. Plexiform neurofibromas are almost diagnostic of von Recklinghausen’s disease (neurofibromatosis1). Other findings in von Recklinghausen’s disease include any two of the following:
1. Numerous café-au-lait macules >5mm
2. Two neurofibromas of any type or one plexiform neurofibroma
3. Freckling in the auxiliary or inguinal regions
4. Optic glioma
5. Hamartomas of the iris (Lisch nodules)
6. Boney dysplasias
7. First degree relative with neurofibromatosisNeurofibromatosis is caused by mutations in the NF1 gene on chromosome 17q.
Incorrect
Answer: Plexiform neurofibroma
Histology: In contrast to this first case in which the tumor arose from the surface of the nerve, this neoplasm clearly involves the nerve itself. In fact, a plexus, or group of nerves is involved.
Discussion: This case was also put on conference, not because it is difficult, but because it is such a distinctive example. As noted above, the neoplasm involves a plexus of nerves. The neoplastic cells have serpentine (snake-like) thin nuclei. The interstitium shows “shredded carrots” like collagen and numerous mast cells. These are all of the classical features of a plexiform neurofibroma. Plexiform neurofibromas are almost diagnostic of von Recklinghausen’s disease (neurofibromatosis1). Other findings in von Recklinghausen’s disease include any two of the following:
1. Numerous café-au-lait macules >5mm
2. Two neurofibromas of any type or one plexiform neurofibroma
3. Freckling in the auxiliary or inguinal regions
4. Optic glioma
5. Hamartomas of the iris (Lisch nodules)
6. Boney dysplasias
7. First degree relative with neurofibromatosisNeurofibromatosis is caused by mutations in the NF1 gene on chromosome 17q.
