Posterior fossa cysts are frequently identified on MR studies. This paper takes a different approach to analyzing these cysts based on the pathology of the cyst wall and the embryology of the hindbrain, choroid plexus, and meninges. The type of cyst depends on the histologic components of the cyst wall. Frequent types of posterior fossa cysts are arachnoid, Blake's pouch, and cysts associated with Dandy Walker malformation. All of these cysts may mimic the others in terms of position of the torcula, vermian abnormalities, and mass effect on the cerebellum and occipital bone. A clue to the nature of the cyst may be the position of the choroid plexus in the fourth ventricle; normal in arachnoid cyst, absent in Dandy Walker malformation, and displaced into the superior cyst wall in Blake's pouch. When the cyst wall histology is not known, it is suggested to use a descriptive term such as "retrocerebellar cyst".

Maternal VAD during pregnancy may decrease renal size in the infant at birth. The functional implications of this effect warrant further study.

This type of study cannot prove that surveillance imaging improves survival in children with medulloblastoma because of the effects of lead time and length biases. Despite this, surveillance does appear to be effective in detecting potentially curable medulloblastoma relapses and should be offered to all patients.

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Objective: Postmenopausal women with breast cancer are at increased risk of bone loss because of age related estrogen deficiency face which accelerated with the use of aromatase inhibitors (AIs). We aimed to study the effect on bone mineral density (BMD) and bone formation biomarker osteocalcin level in postmenopausal breast cancer patients, for the first three years of adjuvant hormonal treatment of both groups Tamoxifen versus Anastrozol. Methods: One-hundered postmenopausal breast cancers were prospectively randomized to receive either Tamoxifen 20 mg/day (n = 50) or Anastrozole 10 mg (n = 50). Both BMD and osteocalcin were assessed initially before treatment and then at regular intervals for both groups. Results: Use of Tamoxifen was associated with significant annual decrease in osteocalcin (P = 0.001), whereas Anastrozole group had gradual increase of the annual levels (P < 0.01). BMD decreased significantly in Anastrozole versus Tamoxifen groups (2.6% vs. 0.4%, P < 0.001). Osteoporosis T < -2.5 was reported significantly higher in Anastrozole group (P < 0.01). Women with initial osteopenia in Anastrozole group showed significant decrease in BMD (P < 0.05). The addition of bisphosphonate for patients with early osteoporosis markedly improved both osteocalcin level and BMD. Conclusion: Tamoxifen preserves BMD in postmenopausal breast cancer patients, whereas Anastrozole accelerates age associated fall in BMD especially in the first year of therapy, moreover, the addition of bisphosphonate can help to decrease the skeletal related events associated with treatment to ensure better quality of life with treatment.