WBR0862
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| Author | [[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pathology |
| Sub Category | SubCategory::Pulmonology |
| Prompt | [[Prompt::A 56-year-old man presents to the neurology clinic for 3 weeks of upper and lower extremity weakness. The patient explains that he works as a plumber and that his everyday chores have become much harder since he has started to notice this weakness. Despite this, he has noticed a pattern that allows him to overcome it. He reports that the longer he is at rest, the weaker he feels, and as soon as he exerts himself he restores a lot of the strength in his extremities. Physical exam reveals 2/5 strength in all four extremities, bilateral eyelid ptosis, and absent deep tendon reflexes. With a certain diagnostic suspicion, the physician orders a chest CT that reveals a 2.5 cm mass adjacent to the left stem bronchus. Biopsy of the mass is likely to reveal which of the following findings?]] |
| Answer A | AnswerA::Small dark blue neuroendocrine cells |
| Answer A Explanation | AnswerAExp::This pattern is typical of SCLC. |
| Answer B | AnswerB::Keratin pearls and retracted cells |
| Answer B Explanation | AnswerBExp::This pattern is seen in squamous cell carcinoma. Paraneoplastic syndromes associated with squamous cell carcinoma include PTHrP hypercalcemia. |
| Answer C | AnswerC::Pleomorphic giant cells |
| Answer C Explanation | AnswerCExp::This pattern is typical of large cell lung carcinoma. |
| Answer D | AnswerD::Granuloma formation with caseating necrosis |
| Answer D Explanation | AnswerDExp::This pattern is usually diagnostic of active tubeculosis. |
| Answer E | AnswerE::Granuloma formation without caseating necrosis |
| Answer E Explanation | AnswerEExp::This pattern is usually seen in sarcoidosis and some cases of tuberculosis. |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::Lambert Eaton myasthenic syndrome (LEMS) is a neuromuscular autoimmune disease often presenting in the context of a paraneoplastic syndrome associated with small cell lung cancer. Patients typically present with weakness of the proximal extremities manifesting as difficulty raising arms and rising from a chair. Other symptoms may include diplopia, ptosis, dysphagia and autonomic dysfunction. Small cell lung cancer (SCLC) is an undifferentiated neoplasm and so far the deadliest cancer in men and women. SCLC is known to be associated with paraneoplastic syndromes including ectopic horomone secretion (ACTH and ADH) as well as LEMS. On pathology, SCLC appears as undifferentiated small blue cells that loosely resemble neuroendocrine cells given their origin. these cells are referred to as Kulchitsky cells. SCLC is usually inoperable and responds to chemotherapeutic regimens to different extents. A pathology specimen of SCLC can be seen below.
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| Approved | Approved::Yes |
| Keyword | WBRKeyword::Kulchitsky cells, WBRKeyword::Small cell lung carcinoma, WBRKeyword::Lambert Eaton Myasthenic Syndrome, WBRKeyword::LEMS, WBRKeyword::Paraneoplastic, WBRKeyword::lung cancer, WBRKeyword::myasthenia gravis |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |
