A 2-year-old child presents with a peeling, erythematous rash on the hands and feet. The mother reports that he has become ill tempered and refuses to walk about, preferring to lie in bed. Physical examination reveals an irritable, pale child with photophobia. Temperature is 98.5°F, heart rate is 80/minute, and respiratory rate is 23/minute. Tremor of the tongue is evident. Further history and follow-up evaluation reveal that the child's elder brothers have been playing with liquid mercury. Which is the most likely diagnosis?

Correct Answer: D

Rationale: The correct answer is D) Acrodynia. Acrodynia, also known as pink disease, is a condition caused by exposure to mercury. The symptoms described in the question, such as peeling rash on hands and feet, irritability, tremor of the tongue, and photophobia, are characteristic of mercury poisoning in children. The history of exposure to liquid mercury by the child's brothers further supports this diagnosis. Option A) Measles presents with a different set of symptoms, including fever, cough, runny nose, and a characteristic rash starting on the face and spreading downward. Option B) Fifth disease typically presents with a "slapped cheek" rash on the face and a lacy rash on the body, along with mild symptoms like fever and malaise. Option C) Kawasaki disease presents with fever, rash, swollen lymph nodes, red eyes, and changes in the lips and mouth, but it does not typically involve exposure to mercury. In an educational context, it is crucial for healthcare providers working in pediatric primary care to be able to recognize the signs and symptoms of various conditions, including rare ones like Acrodynia. Understanding the differential diagnosis for a child presenting with a rash and systemic symptoms is vital to providing appropriate care and treatment. Recognition of environmental exposures, like mercury in this case, is also important in the evaluation of pediatric patients.

Correct Answer: D

Rationale: In this scenario, the correct answer is D) 80%. The specificity of a test refers to its ability to correctly identify those without the condition as negative. In this case, we have 150 normal persons tested, out of which the test correctly identified 120 (150 - 30 positive results) as negative. Therefore, the specificity is calculated as (True Negatives / (True Negatives + False Positives)) * 100 = (120 / 150) * 100 = 80%. This means that the test correctly identifies 80% of normal individuals as negative. Option A) 20%, Option B) 40%, and Option C) 60% are incorrect because they do not accurately reflect the specificity of the test based on the information given. Educationally, understanding the concept of specificity in diagnostic testing is crucial for healthcare professionals to accurately interpret test results and make informed decisions regarding patient care. It is essential to differentiate between true negatives and false positives to ensure appropriate diagnosis and treatment.

Correct Answer: C

Rationale: In this scenario, the least important advice for the young couple with a 2-month-old baby girl seeking medical advice for excessive crying is to change the milk formula (option C). This is the correct answer because excessive crying in a 2-month-old infant is unlikely to be solely due to the milk formula and should not be the primary focus of intervention. Adhering to precry cues (option B) is important as it can help parents understand and respond to their baby's needs before crying escalates. Mastering the situation in a relaxed manner (option A) is crucial for parents to effectively manage their stress and respond to their baby's needs calmly. Avoiding sensory overstimulation (option D) is important as it can help create a soothing environment for the baby. In an educational context, this question highlights the importance of prioritizing advice based on the needs of the infant and the situation at hand. It emphasizes the significance of understanding infant cues, parental stress management, and environmental factors in addressing excessive crying in young infants. By focusing on the most relevant advice, healthcare providers can support parents in effectively caring for their child's needs.

Correct Answer: D

Rationale: In this scenario, the correct diagnosis is hemophilia (Option D). Hemophilia is a genetic disorder that impairs the blood's ability to clot properly, leading to prolonged bleeding after minor trauma or injury. In the case presented, the prolonged bleeding from the circumcision site is indicative of a clotting factor deficiency, which is characteristic of hemophilia. Option A, Idiopathic thrombocytopenic purpura, is unlikely in this case because the platelet count is within normal range (170,000). ITP is characterized by a low platelet count, leading to increased bleeding risk, but the platelet count in this patient is not suggestive of ITP. Option B, Platelets function defect, is less likely because the platelet count is normal. Platelet dysfunction usually presents with a low platelet count or abnormal platelet function tests, which are not seen in this case. Option C, Von Willebrand disease, is also less likely as it typically presents with mucocutaneous bleeding symptoms rather than joint swelling after trauma. Additionally, the prolonged APTT in this case is more indicative of a clotting factor deficiency like hemophilia rather than a von Willebrand factor abnormality. In an educational context, understanding the differences in presentation, laboratory findings, and pathophysiology of various bleeding disorders is crucial for healthcare providers to accurately diagnose and manage such conditions. This case highlights the importance of a comprehensive evaluation of bleeding symptoms and laboratory tests to reach the correct diagnosis and provide appropriate care for pediatric patients with bleeding disorders.

Correct Answer: D

Rationale: The correct answer is D) Temporo-mandibular subluxation. In cases of children with anterior mediastinal masses, a CT scan is indicated to assess potential complications such as cardiac tamponade, airway compromise, and carina compression due to the risk of airway compromise and vascular obstruction. Cardiac tamponade is a life-threatening condition where fluid accumulates in the pericardial sac, compressing the heart. Airway compromise can occur due to mass effect on the trachea or bronchi. Carina compression can lead to obstruction of the mainstem bronchi. These conditions require immediate evaluation and intervention. Temporo-mandibular subluxation, on the other hand, is not directly related to anterior mediastinal masses and would not typically be a primary concern in this scenario. Understanding the specific indications for imaging modalities in different clinical situations is crucial for healthcare providers to make informed decisions and provide optimal care for pediatric patients with complex conditions.