Organizing Pneumonia: A Clinical Challenge in a Child With Previous Rhabdomyosarcoma.

Organizing pneumonia is a pulmonary disease of undefined etiology, with few reported cases in children. It may be secondary to chemotherapy, radiation therapy, infectious agents, or hematopoietic cell transplantation. We present a case of an 18-year-old boy who presented to a follow-up consult with respiratory symptoms at the age of 11 years, 8 years after finishing treatment for a prostatic relapse of a pelvic rhabdomyosarcoma. Chest radiography revealed nodular opacities in the left lung, the one in the left lower lobe with silhouette sign with the left hemidiaphragm. Chest computerized tomography showed 2 nodular lesions in the left upper lobe, one of them cavitated, and another nodular lesion in the left lower lobe; 2 of these nodules had surrounding ground-glass opacities. Microbiological work-up, including tuberculosis screening, was negative. Biopsy revealed findings suggestive of organizing pneumonia. He presented spontaneous resolution. This case presented a diagnostic challenge due to rarity of this condition and its indetermined association with the patient's history of rhabdomyosarcoma. With this case, the authors alert that organizing pneumonia must be considered in patients presenting with pulmonary lesions with a history of previous hematopoietic stem cell transplants, lung irradiation, or immunosuppression. Pulmonary metastases and secondary tumors must be considered as a differential diagnosis in patients with a heavily treated relapsed rhabdomyosarcoma.

Hypertrophic pyloric stenosis: tips and tricks for ultrasound diagnosis.

We describe a systematic approach to the ultrasound (US) examination of the antropyloric region in children. US is the modality of choice for the diagnosis of hypertrophic pyloric stenosis (HPS). The imaging features of the normal pylorus and the diagnostic findings in HPS are reviewed and illustrated in this pictorial essay. Common difficulties in performing the examination and tips to help overcome them will also be discussed. Main Messages • Hypertrophic Pyloric Stenosis is defined by thickening of the muscular layer and failure in relaxation of the pyloric canal. • The main diagnostic criterion is a measurement of more than 3mm in thickness of the muscular layer. • Abnormal elongation of the canal is characterised as greater than 12 mm in length.

Lipofibromatosis of the knee in a 19-month-old child.

Lipofibromatosis is a rare benign fibrofatty tumor of childhood. The typical presentation of this tumor is as a poorly demarcated and slow-growing mass involving the subcutaneous or deep soft tissues. Lipofibromatosis was first described in 2000, and since then, a small number of cases have been reported in the literature. We report a case of a 19-month-old boy who presented with a swelling of the anterior aspect of the right knee since birth, which had increased in size out of proportion with his growth. Magnetic resonance imaging was extremely useful because it showed the lipomatous nature of the mass, narrowing the differential diagnosis to the pediatric fibrofatty soft tissue tumors. The histologic biopsy revealed the specific diagnosis of lipofibromatosis. We describe the radiologic and pathologic features of this entity and discuss the differential diagnosis in a young child with a fat-containing limb mass.