Pinch purpura are seen in –
**Core Concept**
Pinch purpura, also known as Schamberg's sign, is a clinical manifestation of platelet dysfunction characterized by the appearance of petechiae or purpura upon gentle pinching of the skin. This phenomenon is often associated with bleeding disorders, particularly those involving platelet function or coagulation factor deficiencies.
**Why the Correct Answer is Right**
The correct answer is related to a specific condition that affects platelet adhesion and aggregation. Pinch purpura is a hallmark feature of Glanzmann's thrombasthenia, a bleeding disorder caused by mutations in the ITGA2B or ITGB3 genes that encode for the alpha IIb and beta 3 subunits of the platelet integrin. This integrin is crucial for platelet aggregation and adhesion to the site of injury. In the absence of functional ITGA2B or ITGB3, platelets are unable to form stable platelet plugs, leading to impaired bleeding control and the characteristic appearance of pinch purpura.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specifically relate to platelet dysfunction or the characteristic clinical presentation of pinch purpura.
**Option B:** This option is incorrect because it refers to a different type of bleeding disorder characterized by coagulation factor deficiencies, not platelet dysfunction.
**Option C:** This option is incorrect because it is not directly related to the clinical presentation of pinch purpura or bleeding disorders involving platelet function.
**Clinical Pearl / High-Yield Fact**
In addition to Glanzmann's thrombasthenia, pinch purpura can also be seen in other bleeding disorders such as Bernard-Soulier syndrome, which is caused by mutations in the GP1BA gene encoding the platelet glycoprotein Ib-alpha subunit. This condition affects platelet adhesion to von Willebrand factor, leading to impaired platelet function and bleeding.
**Correct Answer:** D.