[Mesencephalic Ewing sarcoma: Case report].

Ewing's sarcoma is a malignant neoplasm mainly occurring in the bone, with other locations being exceptional. In the case of primary intracranial presentations, it is essential to rule out metastatic lesions as well as other neuroectodermal tumors that may require different diagnostic and therapeutic approaches. We present a 14-year-old patient who consulted for upper eyelid ptosis of left eye associated with a 2-month history of diplopia, with imaging evidence of extra-axial tumor lesion, located at the level of the interpeduncular cistern.

[Pseudo-thrombotic microangiopathy due to vitamin B12 deficiency in an infant].

Pseudo-thrombotic microangiopathy, or Moschcowitz syndrome, is a rare manifestation of vitamin B12 deficiency. It is characterized by microangiopathic hemolytic anemia, reticulocytes, and hematimetric indices that can be normal or that might present a mild megaloblastosis, and which are associated with neurological manifestations. Vitamin B12 can be found in animal-based protein foods.

[Cat-scratch disease with multiple bone involvement].

Cat-scratch disease is produced by the bacterium Bartonella henselae, a gram-negative bacillus transmitted through cutaneous inoculation by a cat or dog's scratch or bite. It has a wide clinical spectrum, from a typical picture characterized by a regional lymphadenopathy near to the inoculation site to atypical pictures with systemic compromise. Bone compromise is infrequent, it represents around 0.

[Orbital schwannoma in a child with acute proptosis].

Schwannoma is a usually benign primary tumor. It develops from the Schwann cells, which produce the myelin sheath that surrounds the peripheral nerves. It represents less than 10 % of the intracranial tumors, and it is infrequent in the pediatric age.