 This three-year-old child presents with diabetes insipidus. Let's have a look at the imaging, a sagittal non-contrast T1, and a sagittal contrast-enhanced T1-weighted image. Have a gaze for a moment. I'm going to move on to the questions and begin with question number one. All the following produce stalk involvement and contrast enhancement except A, LCH or Langerhans cell histiocytosis B, hematoma the tuber scenario C, sarcoidosis D, lymphoma E, metastasis Question number two. Which of the following stalk lesions is most characteristically associated with age under 10? A, germanoma B, lymphoid hypothesis C, Langerhans cell histiocytosis D, helicitic astrocytoma E, sarcoid Question number three. Which of the following regarding LCH or Langerhans cell histiocytosis is false? A, neurohypophysis is normal B, males greater than females C, often presents with diabetes insipidus D, thickening of the stalk E, formerly known as histiocytosis X Let's go back and look at our three-year-old. The sagittal projection shows involvement of the pituitary gland by a mass with stalk involvement that enhances. In fact, both enhance. There is no subarachnoid space enhancement but there is enhancing tissue in the sino nasal cavity which can be a manifestation of this disease which has low-grade, intermediate-grade and advanced high-grade areas of involvement that might include the viscera when it is a high-grade aggressive form of the disease also previously known as letteracye disease. Let's go back to our questions. Question number one. All the following produce stalk involvement and contrast enhancement except is hamartoma of the tuberous scenario associated with behavioral disturbance and gelastic seizures. Hamartomas have little to no enhancement but the other choices do enhance or cause enhancement of the stalk such as LCH, Langerhansel histiocytosis, sarcoid and abnormality usually seen in adults. Lymphoma, also adults, and metastases especially from breast and lung, also adults which leads us to question number two. Which of the following stalk lesions is most characteristically associated with age under 10? Well, it's not germinoma. That is not a characteristic stalk lesion although it can involve the stalk. Typically, germinomas occur in boys and young men in the pineal region. Lymphoid hypothesis associated with pregnant women. Langerhansel histiocytosis is the correct answer. While astrocytomas of the pilocytic variety could involve the stalk, especially in NF1, this would not be characteristic of either the tumor or the disease NF1 and sarcoid is seen in adults, sometimes young adults, but not under age 10. Question number three. Which of the following regarding LCH is false? The correct answer here is, and it's a tough one, the neurohypophysis or the posterior pituitary gland is normal. That is not the case. In fact, the majority of individuals with LCH or Langerhansel histiocytosis may be missing the posterior pituitary bright spot. But the other choices are true and you might have to come to the answer by eliminating the rest. You may or may not know that males are more often affected than females, but you should absolutely know, even from residency in medical school, that this condition often presents with DI. Thickening of the stalk is a characteristic manifestation. You should know that from your radiology training and everyone knows that this was formerly known as histiocytosis X. So your choices really should boil down to A and B and you just have to know B, males more commonly affected than females, and therefore by process of elimination the correct answer is A. This concludes our discussion of LCH or Langerhansel histiocytosis with discussion of the pituitary stalk. Let's move on, shall we?