Post-test MSK case study

A 31-year-old female complains of facial muscle weakness for 4 months. She claims of recurring eyelids drooping and difficulty chewing food, that worsens throughout the day. Her examination reveals drooping of the left eyelid with limited facial expression. The findings are worsened by repeated muscle use.

Antibodies against which of the following components is MOST likely seen in this patient?  

• Acetylcholinesterase enzyme

• Peripheral neural sheath

• Postsynaptic acetylcholine receptor

• Voltage gated sodium channel

A 14-year-old boy complains of chronic hip pain with limping gait. X-ray reveals an osteolytic lesion surrounded by multiple layers of new bone at the pelvic and femur. Biopsy of the lesion shows round small blue cells.

Which of the following is MOST likely to be found on investigation of this patient?

• Fusion of EWS-FLI1 genes

• RB1 gene mutation

• TP53 mutation  

• VHL gene mutation

A 52-year-old female presents with joint pain and morning stiffness. She claims that her symptoms are worse in the morning and improves throughout the day. During physical examination, swelling and pain on passive motion of bilateral metacarpophalangeal, wrist, and metatarsophalangeal joints are noticed.

Which of the following BEST explain the pathogenesis of this patient’s condition?

• Autoimmune inflammation and destruction of the joint

• Degenerative disorder of joint articular cartilage  

• Deposition of uric acid in the joint space

• Inflammatory damage of hand muscles

A 7-year-old boy with a history of Crohn’s disease is referred to the paediatric clinic for bone pain and an abnormal gait. Physical examination reveals bilateral leg bowing. Blood tests show low levels of serum calcium, phosphate, and vitamin D.

Which of the following is the MOST likely cause of this patient's condition?

• Genetic mutation impairing osteoclast function

• Impaired intestinal calcium reabsorption

• Inadequate dietary calcium intake  

• Insufficient sun exposure

A 29-year-old female presents with a lesion on her upper back. As a lifeguard, she spends a lot of time outdoors. Physical examination shows multiple pigmented lesions on sun-exposed areas, and she is fair-skinned. One lesion on her upper back is asymmetrical, raised, with irregular borders and a uniform dark colour.

Which of the following features MOST suggestive of a malignant lesion?

• Irregular border of lesion

• Location on the upper back

• Raised appearance of lesion  

• Uniformity of lesion colour