During a routine examination of a 10-mo-old male infant, you find a white pupillary reflex of the right eye; the eye movements are normal. You suspect retinoblastoma. Of the following, the BEST confirmatory diagnostic evaluation of this infant is

Correct Answer: B

Rationale: In this scenario, the best confirmatory diagnostic evaluation for a suspected case of retinoblastoma in a 10-month-old infant is option B: examination under general anesthesia by an experienced ophthalmologist. Retinoblastoma is a malignant tumor of the retina that can present with a white pupillary reflex, known as leukocoria. To properly assess the extent and characteristics of the tumor, a comprehensive examination under general anesthesia is essential in young children who may not cooperate with a regular eye examination. This thorough evaluation allows for a detailed assessment of the eye structures, including the retina, optic nerve, and presence of any tumors. Options A, C, and D are not as appropriate in this context. Option A, indirect ophthalmoscopy with slit-lamp examination, may not provide an adequate view of the entire retina, especially in a young child who may not sit still for the examination. Orbital ultrasonography (option C) can be useful in some cases but may not provide the detailed information needed to confirm a diagnosis of retinoblastoma. Brain MRI (option D) is not the primary imaging modality for evaluating retinoblastoma, as it focuses on the brain structures rather than the eye. In an educational context, understanding the importance of a thorough and appropriate diagnostic evaluation is crucial in pediatric healthcare. It highlights the need for specialized care, expertise, and tailored approaches when dealing with specific conditions in children, such as retinoblastoma. By selecting the most suitable diagnostic method, healthcare providers can ensure accurate diagnosis and timely initiation of treatment, ultimately improving patient outcomes and quality of care.

Correct Answer: D

Rationale: In the case of a 5-year-old with ileocecal Burkitt lymphoma presenting with elevated serum uric acid levels, the most effective treatment is recombinant urate oxidase (Option D). This enzyme helps convert uric acid to a more soluble form that can be easily excreted by the kidneys, thereby preventing the development of tumor lysis syndrome (TLS), a potentially life-threatening complication caused by the rapid release of intracellular components from dying cancer cells. Excessive hydration (Option A) could lead to dilutional hyponatremia and worsen the electrolyte imbalances seen in TLS. Sodium bicarbonate (Option B) is used to alkalinize the urine and prevent uric acid crystallization in chronic conditions like gout, not in acute TLS. Xanthine oxidase inhibitors (Option C) like allopurinol are used in chronic management of hyperuricemia but may not be sufficient in the acute setting of TLS. Educationally, understanding the pathophysiology of TLS and the appropriate management strategies is crucial in pediatric oncology. Recognizing the need for prompt intervention with recombinant urate oxidase in TLS can prevent renal failure, cardiac arrhythmias, and other severe complications associated with this oncologic emergency.

Correct Answer: A

Rationale: The correct answer is A) nephroblastoma, also known as Wilms tumor. In a 2-month-old infant with a renal mass, nephroblastoma is the most likely diagnosis due to its common occurrence in young children. Nephroblastoma is the most common renal tumor in children and typically presents as a painless abdominal mass. Option B) neuroblastoma is a tumor that arises in nerve tissue and is less likely in this case due to the presentation of a renal mass. Option C) mesoblastic nephroma is another renal tumor that occurs in infants, but it is more common in the first few weeks of life, making it less likely in a 2-month-old. Option D) clear cell sarcoma is a rare tumor that usually presents in older children, making it less likely in this infant. Educationally, understanding the differential diagnosis of pediatric renal masses is crucial for healthcare providers working with children. Recognizing the typical age of presentation, common characteristics, and imaging findings of different tumors can aid in early diagnosis and appropriate management, ultimately improving patient outcomes.

Correct Answer: A

Rationale: The correct answer is A) elevated lactate dehydrogenase (LDH) level. In nasopharyngeal carcinoma patients, an elevated LDH level is associated with a poorer prognosis. LDH is an enzyme released when cells are damaged or destroyed, indicating more aggressive disease and poorer outcomes. Monitoring LDH levels helps in assessing disease progression and response to treatment. Option B) advanced disease and Option C) extensive cervical lymph node involvement are also poor prognostic factors in nasopharyngeal carcinoma. Advanced disease implies a larger tumor burden and more extensive spread, leading to a worse prognosis. Extensive cervical lymph node involvement indicates a higher stage of the disease, which often correlates with a poorer outcome. Option D) evidence of Epstein-Barr virus (EBV) DNA is not as strong of a prognostic factor compared to the elevated LDH level. While EBV is linked to the development of nasopharyngeal carcinoma, its presence alone does not necessarily dictate a worse prognosis. In an educational context, understanding prognostic factors in nasopharyngeal carcinoma is crucial for healthcare providers involved in the care of pediatric patients. Recognizing these factors helps in determining appropriate treatment plans, monitoring disease progression, and discussing prognosis with patients and their families. Regular assessment and interpretation of these factors contribute to providing optimal care and support to patients with nasopharyngeal carcinoma.

Correct Answer: D

Rationale: In this scenario, the correct answer is option D) vitamin B12. A strict vegetarian diet, especially one that excludes all animal products, can lead to a deficiency in vitamin B12 as it is primarily found in animal-based foods. Vitamin B12 is essential for red blood cell formation, neurological function, and DNA synthesis, crucial for a growing child. Option A) niacin, Option B) thiamin, and Option C) vitamin B6 are incorrect because while a vegetarian diet may impact the intake of these vitamins to some extent, they are not typically deficient in strict vegetarian diets as they can be sourced from plant-based foods. Moreover, vitamin B12 is unique in that it is not readily available in plant-based foods and therefore more likely to be deficient in individuals following a strict vegetarian or vegan diet. Educationally, this question highlights the importance of understanding the specific nutritional needs of children, especially those following restrictive diets. It emphasizes the significance of vitamin B12 and the potential consequences of its deficiency in pediatric patients. Educators can use this scenario to reinforce the importance of a well-balanced diet and the need for supplementation or alternative food sources to meet essential nutrient requirements in children following vegetarian or vegan diets.