Usmle Step 1 MCQ's # 25

Title: Usmle Step 1 MCQ's # 25
Subject: Behavioral Science 

Q NO 25: A 16-year-old girl is brought to emergency room by her parents for severe right toot pain. The patient states that the pain started 1 day prior to presentation. She cannot recall any recent trauma, and denies any past medical or surgical problem. She is active and walks at least 1 hour daily in the nearby forest. She goes to high school and is doing very well. She gets along well with her parents except that they insist she should eat more as her weight has dropped from 130 to 105 pounds over the past year. Which of the following is the most likely diagnosis?

A. Conversion disorder
B. Depression with somatic manifestation
C. Injured medial ankle tendon
D. Metatarsal stress fracture
E. Tick bite 

Explanation: 
The correct answer is D. The patient is not eating well, as mentioned by her parents, and her weight loss (over 15% of baseline) as well as her school performance anil activity level, is consistent with anorexia nervosa. Metatarsal stress fracture is a complication of rigorous prolonged walking or running in this population. While she is malnourished and underweight, she has poor insight and continues to decrease her input and increase her output with prolonged physical activity. The fracture is a complication of increased output beyond the patient’s physical limitation.
Conversion disorder (choice A) is manifested by chronic neurologic pain or deficit without any objective organic cause. This patient’s chief complaint is acute pain without any sign of another neurologic deficit.
Diffuse muscle and joint aches in conjunction with lack of energy and reduced physical activity, is characteristic of depression (choice B). This patient’s pain is localized and she is very active.
Ruptured or injured tendon of the ankle is a common injury, but the patient does not recall any recent injury and localization of the pain is not consistent with medial ankle injury (choice C). 
The girl’s daily walking in the nearby forest raises suspicion for tick bite (choice E) and Lyme disease with secondary joint pain. Arthritis associated with Lyme disease is generally centered around joints, and does not present as acutely as in this patient.