Final answer:
The likely diagnosis for the stated symptoms and chest radiograph findings in a 3-year-old is pneumonia, an infection of the lungs that shows up as opaque patches on radiographs and is often accompanied by symptoms such as fever and chest pain.
Step-by-step explanation:
The most likely diagnosis for a 3-year-old girl with fever, chest pain, and a round paraspinal opacity at the posterior right lung base on a chest radiograph, accompanied by widened intercostal space, is pneumonia.
Pneumonia can be evidenced on chest radiographs as areas of opacity, as the X-rays show consolidations or shadows in the lung regions that should typically be black due to pockets filled with fluid. When a patient presents with symptoms such as fever, chest pain, and abnormal findings on chest radiograph, including opacities or consolidation, pneumonia becomes a leading consideration. The presence of crepitation, as heard through a stethoscope, supports the diagnosis by suggesting the involvement of fluid or mucus within the lung parenchyma. Additionally, a widened intercostal space may suggest inflammation or pleural effusion associated with the infection.
Treatment generally involves antibiotics, and in a clinical setting, healthcare providers may also order sputum cultures and possibly diagnostic tests for other potential underlying viral infections. It is crucial that pediatric patients with symptoms and radiographic findings suggestive of pneumonia receive prompt medical evaluation and appropriate treatment to ensure the best outcome.