A study is designed to investigate the rates of central line–associated blood stream infections (CLABSI) among pediatric hematology/oncology patients. Investigators wish to compare the length of stay (LOS) between subjects receiving three common central line types (totally implanted catheter [port], peripherally inserted central catheter [PICC], and tunneled externalized catheter [TEC]). It is discovered that LOS is not normally distributed. What is the appropriate test for comparing the LOS between patients receiving the three central line types?

Correct Answer: D

Rationale: The correct answer is D: Kruskal-Wallis test. This non-parametric test is used to compare the medians of three or more independent groups when the data is not normally distributed, as in this case with LOS. It is an extension of the Wilcoxon-Mann-Whitney test, which compares two groups. The Kruskal-Wallis test assesses whether the medians of the groups are equal or different by ranking all observations, calculating the sum of ranks for each group, and then comparing these sums. It is appropriate here because it allows for comparison of central line types without assuming normality. The other choices (A: Student's t test and B: ANOVA) require the data to be normally distributed, which is not the case in this scenario. Choice C: Wilcoxon-Mann-Whitney test is for comparing two groups, not three or more.

Correct Answer: B

Rationale: The correct answer is B: Leukocyte adhesion deficiency (LAD) Type II. This patient's symptoms of recurrent bacterial infections, leukocytosis, neutrophilia, short stature, and Bombay blood group (lack of H antigen) are characteristic of LAD Type II. In LAD Type II, there is a defect in fucose metabolism, leading to impaired leukocyte adhesion and migration, causing immune dysfunction. Chediak-Higashi syndrome (A) presents with oculocutaneous albinism, recurrent infections, and giant granules in leukocytes. CD18 deficiency (C) is a type of LAD characterized by mutations in the CD18 gene causing impaired integrin function. Griscelli syndrome (D) presents with silvery hair, immunodeficiency, and neurological deficits, not matching this patient's symptoms.

Correct Answer: C

Rationale: The correct answer is C: T-cell numbers in infants are higher than in adults. This is because infants have a relatively higher proportion of T-cells compared to adults due to their underdeveloped immune system. T-cell numbers decrease with age as the immune system matures and adapts to the environment. Rationale: 1. T-cells play a crucial role in the immune response, especially in infants who rely heavily on cellular immunity. 2. NK-cell numbers do not follow the pattern described in option A, as they are important in early immune responses. 3. B-cell numbers do not decline with age as stated in option B, as they are responsible for antibody production throughout life. 4. Option D is incorrect as infants actually have higher lymphocyte counts compared to adults due to their developing immune system.

Correct Answer: D

Rationale: The correct answer is D because the patient has residual lung nodules after initial chemotherapy, indicating a need for intensified treatment. Adding cyclophosphamide and etoposide to the chemotherapy regimen can improve outcomes in patients with combined loss of heterozygosity for 1p and 16q. Radiation to both the lungs and flank targets all remaining disease sites effectively. Choice A is incorrect because it does not address the need for intensified treatment with additional agents or radiation to the lungs, where residual disease remains. Choice B is incorrect as it only includes radiation to the flank and not the lungs, which are still harboring disease. Choice C is incorrect because although it adds cyclophosphamide and etoposide, it does not include radiation to the lungs, which is necessary for comprehensive disease control.

Correct Answer: A

Rationale: The correct answer is A because both parents are silent carriers, each passing a deleted alpha globin allele to their child, resulting in a trans-deletion genotype alpha thalassemia trait. This explanation aligns with the child's abnormal complete blood count and the family history. Choice B is incorrect because it states that the mother has cis deletion alpha thalassemia, which is not supported by the information provided. Choice C is incorrect as it suggests a new spontaneous mutation causing alpha thalassemia in the child, which is not consistent with the genetic inheritance pattern described. Choice D is incorrect because it claims both parents carry cis deletions in the alpha globin gene cluster, which contradicts the scenario where the parents are silent carriers.