NEET-PG 2018 — Pediatrics

Q: In a child with rickets which part of the bone is affected?

C. ***C*** - C points to the **growth plate (physis) and metaphyseal region**, which is the **primary site of pathology in rickets**. - Rickets causes defective mineralization at the growth plate where endochondral ossification occurs, leading to accumulation of unmineralized osteoid and disorganized chondrocyte columns. - The **metaphysis** (the region including the growth plate) shows the characteristic radiological findings: widening, fraying, cupping, and loss of sharp margins. *A* - A indicates the **diaphysis** (shaft of the bone), which consists of mature cortical bone. - The diaphysis is **not primarily affected** in rickets, though severe cases may lead to bowing deformities due to bone softening. - The initial and primary pathological changes occur at the actively growing regions, not the shaft. *B* - B points to the **metaphysis**, which is the flared region of long bone adjacent to the growth plate. - The metaphysis is indeed significantly affected in rickets, showing widening and irregular mineralization. - However, if the image distinguishes between the broader metaphyseal region (B) and the specific growth plate zone (C), then C represents the more precise site where the pathological process of defective mineralization originates. *D* - D points to the **epiphysis**, the rounded end of the long bone that forms part of the joint. - The epiphysis consists of already-formed bone and is **not the primary site** of rickets pathology. - Rickets affects the zone of provisional calcification at the growth plate, not the pre-existing epiphyseal bone.

Q: In a neonate with the following findings, what is the likely etiology of hypothyroidism? (NEET Pattern 2018)

Thyroid dysgenesis. ***Thyroid dysgenesis*** - The image shows a neonate with **cretinism features** (e.g., puffy face, large tongue, umbilical hernia) and a **newborn screening card** being collected (heel prick blood spots). - **Thyroid dysgenesis** (aplasia, hypoplasia, or ectopic thyroid) is the most common cause of **congenital hypothyroidism**, accounting for about 85% of cases. *Chronic lymphocytic thyroiditis* - Also known as **Hashimoto's thyroiditis**, this is an **autoimmune condition** that primarily affects adults and older children, not typically neonates. - While it can lead to hypothyroidism, it is an **acquired** rather than a congenital cause. *Thyroid dyshormonogenesis* - This refers to genetic defects in the **synthesis of thyroid hormones** due to enzymatic deficiencies within a structurally normal thyroid gland. - While it is a **congenital cause** of hypothyroidism, it is less common than thyroid dysgenesis (accounting for about 10-15% of cases). *None of above* - This option is incorrect because **thyroid dysgenesis** is a highly likely etiology given the clinical presentation and context of newborn screening.

22 Questions — Page 3 of 3

Q21

In a child with rickets which part of the bone is affected?

Q22

In a neonate with the following findings, what is the likely etiology of hypothyroidism? (NEET Pattern 2018)