WBR0246
| Author | [[PageAuthor::Rim Halaby, M.D. [1], Alison Leibowitz [2] (Reviewed by Alison Leibowitz)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pathology |
| Sub Category | SubCategory::Gastrointestinal |
| Prompt | [[Prompt::A 62-year-old male presents to the physician's office with complaints of abdominal pain, which has been worsening over the past four months. The dull pain is localized in the epigastric area and persistently increasing in intensity, independently from food intake or change in posture. Upon further questioning, he describes symptoms of increasing fatigue and weight loss. A CT scan displays a mass in the stomach and an endoscopy-guided biopsy of the mass reveals clusters of thin, elongated spindle cells. Which of the following immunohistochemistry findings is most helpful in diagnosing the type of tumor in this patient?]] |
| Answer A | AnswerA::C-kit |
| Answer A Explanation | [[AnswerAExp::C-kit oncogene is associated with GIST. C-kit gene encodes the human homolog of the proto-oncogene c-kit, also called CD117.]] |
| Answer B | AnswerB::Ret |
| Answer B Explanation | [[AnswerBExp::The Ret oncogene is often associated with MEN syndrome, type IIa and IIb.]] |
| Answer C | AnswerC::Abl |
| Answer C Explanation | [[AnswerCExp::The Abl oncogene is often associated with CML.]] |
| Answer D | AnswerD::Ras |
| Answer D Explanation | [[AnswerDExp::The Ras oncogene is often associated with colon carcinoma.]] |
| Answer E | AnswerE::C-myc |
| Answer E Explanation | [[AnswerEExp::C-myc is associated with Burkitt's lymphoma.]] |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::The patient's symptoms of epigastric pain, fatigue, and weight loss, in conjunction with the CT finding of a mass in the stomach, points towards the diagnosis of malignancy. The spindle cells on pathology are often diagnostic for a gastrointestinal stromal tumor (GIST), which can be confirmed by positive immunohistochemistry for C-kit. Educational Objective: C-kit, also called CD 117, is often associated with gastrointestinal stromal tumors (GIST). |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Cancer, WBRKeyword::GIST, WBRKeyword::Gastrointestinal stromal tumor, WBRKeyword::Imatinib, WBRKeyword::Tyrosine kinase inhibitor, WBRKeyword::Chemotherapy |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |