 Hello everyone, welcome back to a new session on dentistry and more. Today's topic in oral pathology is Pemphicus vulgaris and bullus pemphigoid. The names are little bit same but there is lot of difference between these two, auto immune, blister formation, skin disease and along with that we will be learning what is Nikolsky sign and what is Chang test or Chang cell. So let's see the basic differences between Pemphicus vulgaris and bullus pemphigoid. So what is the fundamental difference between Pemphicus and Pemphigoid. There are lots of differences between these two skin diseases. The common thing is these both are autoimmune diseases. We know what is autoimmune diseases. Our own antibodies acting against our own cell and causing destruction in one way or other. So Pemphicus and Pemphigoid both are autoimmune antibodies but the mechanism of blister formation is different. In Pemphicus it is intradermal blister formation. We will go into detail later. Now let's see what is intradermal. It is like the acantholysis that is the detachment of cells that is the cell adhesion is lost between the cell layers that is between the epithelial layers. So the basal layer is intact here. The basal layer is intact here. So it is forming within the epithelium that is intradermal blister formation. So it is forming within the epithelium. But in Pemphigoid the epithelium is not affected. You can see the basal layer is here and all the other layers are here. There is no much problem in within the epidermis but the problem is the epidermis and the basal membrane. So it is sub-epidermal. This is intra-epidermal blister formation. This is sub-epidermal blister formation. So that is the unique difference between these two. So this is forming within the epidermis. This is underneath the epidermis that is between the basal membrane and epithelium. So that is the difference between Pemphigoid and Pemphigoid. Now let's see the other differences. The Pemphicus vulcaris which is seen common in younger patient but whereas the bullus Pemphigoid it is high incidence seen in elder age group and this is mucosal involvement is very common and oral relations. But in Pemphigoid the mucosal involvement is very rare and there is no oral relations because it is a very deeper relations because as shown here. So if you know this concept explaining these differences is very much easier because mucosal involvement is very common because it is the intra-epidermal problem or blister formation. This is sub-epidermal. So this will be definitely in a very deeper location. So mucosal involvement will be common in Pemphicus. Pemphigoid it will be very rare. So the antibodies so I said it is a autoimmune system. So autoantibody is working against our own cells. So antibodies are acting against Desmogline tree. So you can see here the antibodies causing separation of these cells that is it affects Desmogline tree. Desmogline tree are the keratin fibres or the fibres which connects the cells. So it affects Desmogline tree. So it separates the cells and forming these blisters whereas this is acting against Hemidesmosome. Hemidesmosomes are structures which keeping the basal membrane and epithelium close together. So it acts here between Hemidesmosome attachment that is between the basal membrane and epithelium. So the Pemphicus is intra-epidermal blisters that is superficial. So I explained in detail that is intra-epidermal whereas the sub-epidermal D-blisters are seen in Pemphigoid. This is D-blisters and sub-epidermal that is underneath of epidermis this is intra-epidermal. The blisters are flaccid and rupture very easily because it is superficial. This is very tense and firm because it has a thick layer of epidermis over the blister. But here the layer is not very concrete so very firm so it is easily rupturable the Pemphicus. So that is why I was saying if you know this concept it is very easy to understand. Nikolsky sign is positive and Nikolsky sign is negative. So let us see what is exactly Nikolsky sign. It was put forward by a scientist Nikolsky. The thing is when we apply lateral pressure so when we apply lateral pressure or a shearing force the skin ruptures that is Nikolsky sign. So when it ruptures when there is a superficial blisters or a intra-epidermal blister formation or intra-epidermal acantholysis is there there will be Nikolsky sign. So it is most commonly seen in Pemphicus vulcaris and it will not be seen in pullus pemphigoid because it is a very deeper lesion. It has a thick epidermis above the blister so if you apply lateral pressure or shearing force there will not be any loss of or any rupture of the superficial skin. So that is Nikolsky sign it is to identify the intra-versus sub-epidermal blisters. So Nikolsky sign which is seen in Pemphicus vulcaris and also it is seen in Stephen Johnson syndrome. So it is nothing but a significant indicator of active acantholysis and altered structural integrity within the epidermis. So which allows a physician to determine the level of split in the skin so as to distinguish between intra-epidermal and sub-epidermal blistering diseases in the clinical setting. That is the importance of Nikolsky sign. So these are Nikolsky sign positive skin lesions. So that is Nikolsky sign when we apply lateral pressure or shearing force there will be rupture. And the acantholysis is seen on Changsmear and it is not seen on Changsmear. So acantholysis is nothing but the loss of detachment or loss of the intra-dermal connection. So if the intra-dermal connections or intra-epidermal connections is lost that is known as acantholysis that the acanthosis is lost. This is a cell-to-cell connection so that is lost. So when we take a smear we can see Changsmear. Changsmear is nothing but a multi-nucleated giant cell fusion of the acantholytic keratinocytes. So when there is acanthosis happening so these acantholytic keratinocytes will coalesce to form a multi-nucleated giant cell which is known as Changsmear. These cells will be observed in testing that is staining and we can keep it as a positive sign for superficial lesion that is Pemphigus vulgaris. So Changsmear is positive in all these conditions and one more thing is the prognosis. The prognosis for Pemphigus vulgaris is poor but whereas the pullus pemphigoid is good prognosis. The patient's recovery is very good with pullus pemphigoid. And the tombstone apparatus is seen with Pemphigus vulgaris. You can see the tombstone appearance of the basal membrane. So this is the tombstone appearances just the stone we keep for graveyard. So that collection of tombstone you can see in Pemphigus but that is not very visible here because there is no intra epithelial or intradermal separation. So here it is basal membrane is separated here the intradermal separation is there. So we can very clearly see in the tombstone appearance in Pemphigus. So while coming to immunofluorescence so in Pemphigus vulgaris we have net like IgG whereas in the pullus pemphigoid we have linear IgG structures. So that is all about Pemphigus vulgaris and pullus pemphigoid. So it is the difference as I mentioned it is the intradermal and sub epidermal. So you understand this concept clear then you apply this into the differences it is very easy to understand and learn about Nikolsky sign and Chang test or Chang cell. So it is very commonly asked what is Nikolsky sign and Chang test or Chang cells and also the tombstone appearance. Tombstone appearances are seen in many conditions and one among this is Pemphigus vulgaris. So I will come up with a new topic in the industry and more. 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