Case Study 10Harry Kellermier, M.D.

The patient is a 27-year-old female with a history of complex partial seizures starting at age 16.  A typical episode lasts less than one minute and consists of her staring blankly ahead and occasionally jerking her hand.  She is usually disoriented after the episodes.An MRI is performed.  What type of MRI sequence is this?

Question 1

T2 FLAIR

Answer

Question 2Describe the MRI.

AnswerThere are multiple subcortical foci of increased T2 signal intensity (2 on the left, 1 on the right).

Question 3After reviewing additional history on this patient, you learn she has a renal tumor, flat, brown marks on her skin, and red bumps on her nose and cheeks.  What genetic disorder should you suspect?

AnswerTuberous sclerosis.  The flat brown marks are most likely cafe-au-lait spots, the red bumps on her nose and cheeks are facial angiofibromas (adenoma sebaceum), and the renal tumor is probably an angiomyolipoma.

Question 4The patient then undergoes cortical mapping and excision of her epileptogenic focus, yielding the following specimen.  What CNS findings are associated with tuberous sclerosis?

AnswerTubers, epilepsy, heterotopias, subependymal nodules, and subependymal giant cell astrocytoma.

Question 5What are tubers and how do they appear grossly and histologically?

AnswerTubers are thought to represent areas of abnormal neuronal migration.  Grossly, they appear as firm nodules projecting above the surface of the brain.  They range in size from millimeters to several centimeters and are pale in color. Microscopically, the normal cortical architecture is disrupted by large, bizarre cells with prominent nucleoli.  These cells possess short, thick cytoplasmic processes and may exhibit single or multiple nucleoli.  Associated with these cells is astrogliosis, loss of myelin, and occasional calcification.

Question 6What is the name of the characteristic cell found in tubers?

AnswerBalloon cells.  They express both glial and neuronal characteristics.

Question 7Describe the histologic findings.

Click the following links to view slides: H&E, Vimentin

AnswerThere is a focus within the subcortical white matter showing proliferation of balloon cells and gliosis.  Rosenthal fibers are seen.  The surrounding white matter also appears gliotic and pale.  Subpial gliosis is also noted.  Vimentin immunostains highlight the balloon cells and reactive astrocytes.

Question 8What is the most commonly affected organ in tuberous sclerosis?

AnswerThe brain.

Question 9What genetic mutations have been linked to tuberous sclerosis?

AnswerMutations in the gene encoding the protein hamartin at 9p34 and the gene encoding the protein tuberin at 16p13.3.

Question 10What are some other systemic manifestations of tuberous sclerosis?

AnswerAngiomyolipoma, renal cysts, pulmonary lymphangioleiomyomatosis, cardiac rhabdomyomas, facial angiofibromas, cafe-au-lait spots, ungual or subungual fibroms, ash leaf spots, forehead plaques, ocular astrocytic hamartomas, colobomas, papilledema.

Question 11What is the other name for subpial gliosis associated with epilepsy?

AnswerChaslin's gliosis