The correct answer is B.
The patient has orbital cellulitis, which is an infection of the soft tissue posterior to the orbital septum. The most common organisms in orbital cellulitis are S. aureus, S. pneumoniae, and in children, H. influenzae. Most cases occur secondary to a bacterial sinus infection. It can also be caused by upper respiratory tract infections, dental infections, trauma, or ocular surgery. Signs and symptoms include proptosis, ptosis, lid erythema/edema, pain with eye movement, diplopia, and nasal discharge or tenderness. Patients with suspected orbital cellulitis should undergo emergent CT to confirm the diagnosis and evaluate for subperiosteal abscess. Treatment includes broad-spectrum antibiotics. Surgical management can be considered if the condition worsens with treatment. Preseptal cellulitis (Choice A) can also present with periocular pain and swelling; however, it does not present with proptosis. There should also be an inciting event, such as a stye, bug bite, or trauma. Acute angle glaucoma (Choice C) presents as pain, conjunctival injection, and a dilated, non-reactive pupil. Conjunctivitis (Choice D) presents with conjunctival injection, discharge, and a gritty sensation in the eye. Retinoblastoma (Choice E) is a common ophthalmic malignancy in childhood that presents with leukocoria and reduced vision.
Source: Hong ES, Allen RC. Orbital Cellulitis in a Child. EyeRounds.org. January 12, 2010; Available from: http://www.EyeRounds.org/cases/103-Pediatric-Orbital-Cellulitis.htm.
