Question of the Day

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USMLE Step 2 Question of the Day

November 10, 2022

A 65-year-old male presents to his primary care doctor because he has been experiencing weakness over the past couple of weeks. The patient notes that the weakness is greatest in the mornings and he feels like he cannot move his arms or keep his head up. However, as the day goes on, he finds that his strength increases. On further questioning, he admits to a dry cough that is sometimes blood-streaked and has lost 20 pounds over the past 4 months. He is a long-time smoker who smoked 1-2 packs per day since the age of 18. The doctor orders a chest x-ray which shows a 4-cm irregular nodule near the right mainstem bronchus. What is the most likely primary malignancy affecting this patient?

Correct Answer: 

D. Small cell carcinoma of the lung

Explanation:

This patient is suffering from Lambert-Eaton myasthenic syndrome (LEMS) which is most often found in association with small cell carcinoma of the lung (option D). LEMS is similar to myasthenia gravis but it is caused by antibodies against the pre-synaptic Ca channels. Unlike myasthenia gravis, LEMS improves over the course of the day or with repetitive activity. In addition, small cell carcinoma is usually a centrally located tumor in the lung.

Quick Concepts:

  • Small cell carcinoma association
    • Lambert Eaton syndrome

Summary:

Patients with a long history of smoking, a muscular weakness that is worse in the mornings, and a centrally located lung mass, should be evaluated for small cell carcinoma of the lung with associated Lambert Eaton syndrome.

Correct Answer: 

D. Small cell carcinoma of the lung

Explanation:

This patient is suffering from Lambert-Eaton myasthenic syndrome (LEMS) which is most often found in association with small cell carcinoma of the lung (option D). LEMS is similar to myasthenia gravis but it is caused by antibodies against the pre-synaptic Ca channels. Unlike myasthenia gravis, LEMS improves over the course of the day or with repetitive activity. In addition, small cell carcinoma is usually a centrally located tumor in the lung.

Quick Concepts:

  • Small cell carcinoma association
    • Lambert Eaton syndrome

Summary:

Patients with a long history of smoking, a muscular weakness that is worse in the mornings, and a centrally located lung mass, should be evaluated for small cell carcinoma of the lung with associated Lambert Eaton syndrome.


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