Pa l a b r a s c l a v e : Tu m o r e s t r o m a l , Tu m o r gastrointestinal. IntroducciónEl Tumor Estromal Gastrointestinal (GIST) es la neoplasia mesenquimatica más común del tracto digestivo; sin embargo su frecuencia representa solo un 0.1 a 3% de las neoplasias gastrointestinales. Anteriormente, eran clasificados como leiomiomas, leiomiosarcomas, leiomioblastomas, schwannomas o neurofibromas del tracto digestivo (1) . Sin embargo, la observación en el año 1983, que los GISTs expresaban en los estudios inmunohistoquimicos un receptor para el factor de crecimiento de la tirosina kinasa, llamado CD117 en un 100% de los casos, y la proteína CD34 en el 70% de los casos, estableció la diferencia con los tumores mencionados. Otros posibles marcadores tumorales incluyen vimentina, actina, proteína S-100 y desmina.Los GISTs se originan de una célula precursora común, la célula intersticial de Cajal o marcapasos intestinal, o bien de una célula troncal más primitiva de la cual derivan la célula de Cajal y las células musculares lisas (2) .Se pueden localizar en cualquier parte del tracto gastrointestinal, así como también en omento, mesenterio o retroperitoneo.Un 70% se ubican en estómago (4) , un 20-30% en el intestino delgado y un 7% en la región anorrectal. A diferencia del resto del tubo digestivo, en el esófago los leiomiomas son más frecuentes.El 70-80% de los GISTs son benignos. Hallazgos sugerentes de malignidad son localización extragástrica, tamaño superior a 5 cm, un alto

Introduction. Langerhans' cell histiocytosis is an uncommon disease, with various radiological presentations. Its cause remains unknown, with the pathological hallmark being proliferation of Langerhans' cells. The spectrum of disease ranges from solitary bone lesions to multisystemic affection. Usually, the first diagnostic test performed is the plain radiograph, and the radiological findings may be hard to analyze. Differential diagnosis should include osteomyelitis, Ewing's sarcoma and lymphoma. Objectives: To show the plain radiographic findings of LCH, that allow the radiologist to suspect it. Methods and materials: The clinical and radiological presentations of the biopsy proven LCH cases of the National Bone Tumor File (RENATO) between the years 1961 and 1999 were analyzed retrospectively. Results: From a total of 59 patients, 58% were boys and 42% were girls. Age ranged from 0.8 to 17 years, with an average of 6.1 years. Medical history was obtained in 56 cases (95%). The mean duration of symptoms at diagnosis was 5,5 months, with pain at the site of affection being the most frequent 50/59 of them. Forty-eigth patients (81%) presented with a solitary bone lesion and 11 (19%) presented with two or more lesions; 35 patients had afection of long bones and 26 of axial skeleton. The most frequently radiological pattern was a purely osteolytic lesion (n=45). 13 patients presented with a permeative lesion and a vertebra plana was found in 3. Periostal reaction and soft tissue mass were found in 30 and 29 cases respectively. Conclusions: Despite the fact that LCH has several radiological manifestations, its diagnosis should be suspected by the radiologist. This study with biopsy proven cases of Langerhans´ cell histiocytosis allows us to characterize the manifestations of this disease in the skeleton and is useful for the differential diagnosis of a bone lesion in the pediatric patient.

Endometriosis is a chronic and recurrent gynecological disorder that affects women of childbearing age; it may be manifested by infertility or chronic pelvic pain. Evaluation of this disease by clinical examination and ultrasound scan is usually of limited value. With the new advances in technology, MRI has proved to be highly helpful in the assessment of endometriosis, both for diagnosis and for evaluation of its extent. This dysfunction may adversely affect the organs of the reproductive system as well as gastrointestinal and genitourinary systems. Given MRI capability of tissue characterization and high contrast resolution, it is recommended as first-line technique in the evaluation of this condition.

Bariatric surgery has developed considerably over recent years due to the progressive increase in obesity worldwide. The laparoscopic sleeve gastrectomy is a new restrictive technique, with promising initial outcomes. CT images play an important role in postoperative evaluation as well as in complication management in patients undergoing this surgical technique. Here we review the role of abdominal computed tomography in the study of potential complications.