A 6-month-old boy is brought to the office for a well-child visit. The patient sits with support, mouths toys, and responds to his name. He has not yet started babbling or using a pincer grasp. The patient drinks 24-28 oz daily of donated, pasteurized breast milk obtained through a local milk bank. He was adopted from Uganda at age 2 months. The only available birth history is that the patient was born full-term and that labor and delivery were uncomplicated. Family history is unknown. Immunizations are up to date. He has no chronic medical conditions and takes no medications. Height and weight are at the 20th and 40th percentiles, respectively. Head circumference is at the 30th percentile. The patient has no dysmorphic facial features. The anterior fontanel is open and flat, and the skull bones are soft and flexible to pressure. Bilateral swelling of the wrist is present. There is no bowing of the lower extremities. Cardiopulmonary and abdominal examinations are normal. An x-ray of the wrist is performed. Which of the following is the most likely cause of this patient's x-ray abnormality?

Question

A 6-month-old boy is brought to the office for a well-child visit.  The patient sits with support, mouths toys, and responds to his name.  He has not yet started babbling or using a pincer grasp.  The patient drinks 24-28 oz daily of donated, pasteurized breast milk obtained through a local milk bank.  He was adopted from Uganda at age 2 months.  The only available birth history is that the patient was born full-term and that labor and delivery were uncomplicated.  Family history is unknown.  Immunizations are up to date.  He has no chronic medical conditions and takes no medications.  Height and weight are at the 20th and 40th percentiles, respectively.  Head circumference is at the 30th percentile.  The patient has no dysmorphic facial features.  The anterior fontanel is open and flat, and the skull bones are soft and flexible to pressure.  Bilateral swelling of the wrist is present.  There is no bowing of the lower extremities.  Cardiopulmonary and abdominal examinations are normal.  An x-ray of the wrist is performed.  Which of the following is the most likely cause of this patient's x-ray abnormality?

Quizplus · Accepted Answer

11ec25c8_d667_3e46_bc81_e317207abcd5_MD0003_00 Nutritional rickets is most commonly caused by deficiency of vitamin D, which is necessary for calcium metabolism and skeletal growth. Risk factors include limited sun exposure and increased skin pigmentation. An exclusive diet of breast milk without vitamin D supplementation, as in this infant, is a major risk factor because breast milk alone contains inadequate vitamin D. Deficiency of vitamin D and calcium leads to poor bone mineralization and accumulation of growth plate cartilage. Infants may have craniotabes (skull bones that depress with pressure), as seen here. Widened wrists may be apparent due to growth plate enlargement. Additional findings include radial/ulnar bowing and delayed fontanel closure. Lower extremity bowing (genu varum) is apparent once children become weight-bearing. X-ray of rapidly growing skeletal areas (eg, wrists, knees) is a helpful diagnostic tool. X-ray findings include metaphyseal widening with cupping and fraying (white arrow), as seen here. Costochondral joint widening is also classic. X-ray findings Treatment includes vitamin D and calcium supplementation. (Choice A) Systemic juvenile idiopathic arthritis is an autoimmune inflammatory disorder that presents with fever, arthritis, and rash, none of which are present here. In addition, x-ray findings include soft tissue swelling and loss of joint space. (Choice B) Hurler syndrome is an autosomal recessive lysosomal storage disease that presents with dysostosis multiplex, a range of skeletal findings including shortened and thickened long bones. Patients also typically have coarse facial features (eg, wide nasal bridge, flat midface), developmental delay, and frequent infections, none of which are seen here. (Choice C) HIV can be transmitted via breast milk. However, clinical features in infants include hepatosplenomegaly, lymphadenopathy, and failure to thrive, not the bony abnormalities seen here. In addition, milk banks screen donors for infectious disease and pasteurize milk to destroy pathogens, including HIV. (Choice D) Congenital syphilis is often asymptomatic but may cause skeletal abnormalities, including craniotabes and osseous destruction of the long bones, not metaphyseal cupping and fraying. Other findings in symptomatic patients include hepatosplenomegaly, rash, and lymphadenopathy, which are also not seen here. (Choice E) Nonaccidental trauma can present with localized swelling and no reported history of trauma. However, new and/or old fractures would be expected on x-ray. In addition, craniotabes would not be seen. Educational objective: Nutritional rickets classically occurs in exclusively breastfed infants without vitamin D supplementation. Presentation includes craniotabes (soft skull bones) and forearm deformities (widened wrists, radial/ulnar bowing). Lower extremity bowing occurs once patients are weight-bearing. References: Rickets. (http://www.ncbi.nlm.nih.gov/pubmed/29265106) Nutritional rickets. (http://www.ncbi.nlm.nih.gov/pubmed/21274312)

A 6-Month-Old Boy Is Brought to the Office for a Well-Child