WBR0295
| Author | [[PageAuthor::Ogheneochuko Ajari, MB.BS, MS [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pathophysiology |
| Sub Category | SubCategory::Dermatology |
| Prompt | [[Prompt::A 42-year-old male presents to the ER with a fever, chills, and facial pain, which had began three days prior. Upon further questioning, he states that he accidentally cut his face while shaving. Physical examination reveals a very red and swollen skin lesion with blisters and a raised border that is warm to touch on the left side of the face. Which of the following mechanisms is true about the lesion?]] |
| Answer A | AnswerA::The redness and warmth is due to histamine-mediated vasoconstriction of arterioles |
| Answer A Explanation | AnswerAExp::Incorrect. The redness and warmth is due to histamine-mediated vasodilation of arterioles and not due to vasoconstriction of arterioles |
| Answer B | AnswerB::The redness and warmth is due to histamine-mediated vasodilation of venules |
| Answer B Explanation | AnswerBExp::Incorrect. The redness and warmth is due to histamine-mediated vasodilation of arterioles and not due to vasodilation of venules |
| Answer C | AnswerC::The redness and warmth is due to histamine-mediated vasodilation of arterioles |
| Answer C Explanation | AnswerCExp::Correct. See explanation |
| Answer D | AnswerD::The swelling is due to histamine mediated decrease in permeability of venules |
| Answer D Explanation | AnswerDExp::Incorrect. The swelling is due to histamine mediated increase and not a decrease in permeability of venules |
| Answer E | AnswerE::The pain is caused by PGE2 sensitization of specialized nerve endings to the effects of serotonin |
| Answer E Explanation | AnswerEExp::Incorrect. The pain is caused by PGE2 sensitization of specialized nerve endings to the effects of bradykinin |
| Right Answer | RightAnswer::C |
| Explanation | [[Explanation::This is a case of Erysipelas of the face due to group A streptococcus. Signs of acute inflammation present in this patient include Rubor (redness), Calor (warm to touch), Tumor (swelling) and Dolor (pain). The infection is associated with a warm skin (calor) and pain (dolor). The redness and warmth experienced by this patient is due to histamine-mediated vasodilation of arterioles Educational Objective: |
| Approved | Approved::Yes |
| Keyword | |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |