The Application Of Imaging Techniques And Molecular Biological Techniques In The Diagnosis Of Some Dermatoses

Background:The classic diagnosis of skin diseases depends on the patient's medical history,physical examination(mainly dermatological examination)and histopathological results.The histopathological examination is the gold standard for many skin diseases.However,problems like the following still exist:1.It should not be widely used as screening technology for skin diseases because biopsies caused wound.2.Sometimes histopathological results is difficult to determine the etiology.Therefore,it is necessary to explore new diagnostic techniques for skin diseases.Although imaging techniques are widely used in clinical diagnosis,their applications in dermatology need to be further discussed.Recently,high frequency ultrasound is used to diagnose some skin diseases,but it has not been widely promoted in China.Droplet digital PCR technology,a newly emerging molecular biology technology in recent years,is based on the technology of water-in-oil emulsion droplets to analyze nucleic acid quantitatively without standard curves.Previous studies about the technology in infectious diseases showed obvious advantages in pathogenic microorganism detection.However,there is no extensive clinical practice in China.In this paper,the application values of high frequency ultrasonography and the droplet digital PCR in the diagnosis of certain dermatological diseases are investigated to extend applications of the two techniques in dermatology.Objectives:1.To explore the application value of high frequency ultrasonography,one of the imaging techniques,in screening and diagnosis of bullous skin diseases.2.To establish and evaluate the application of droplet digital PCR in leprosy diagnosis,especially in the paucibacillary leprosy,and deepen the understanding of molecular biology technology to promote the development of dermatology.Methods:1.Bullous pemphigoid and pemphigus vulgaris,belonging to the group of subepidermal and intraepidermal bullae respectively,are two potentially devastating blistering skin diseases.We performed high-frequency ultrasonography with 22MHz and 50MHz probes in those patients as prototypes to study the value of HFUS in discriminating blister location,compared with histopathological diagnosis.2.Firstly,the droplet digital PCR was established for the diagnosis of leprosy by multibacillary leprosy patients and control patients.Then,it was applied in the patients with paucibacillary leprosy,whose results were compared with the results of Taqman qPCR.Results:1.We could see clearly that the image of patients with bullous pemphigoid illustrated a well-defined anechoic subepidermal cystic structure with a hypoechoic subjacent upper dermis.And sonographic findings of patients with pemphigus vulgaris revealed that there is a clear boundary at the bottom of the well-defined and anechoic areas.The obvious difference was that the image of subepidermal blister showed no hyperechoic line and that of intraepidermal blisters demonstrated the hyperechoic line at the bottom of anechoic area by 22MHz or 50MHz probe.2.Out of 33 paucibacillary patients detected by the developed droplet digital PCR assay,qPCR positive in 15(45%)cases.In contrast,droplet digital PCR detected M.leprae in 28(85%).A total of 15(15%)cases tested positive by both diagnostic tools i.e.qPCR and droplet digital PCR.There was no case in which qPCR was positive and PCR was negative.droplet digital PCR confirmed the diagnosis in 13(72%)out of 18 skin tissues which qPCR negative.Conclusions:1.High frequency ultrosound could be used as an aid to screen and diagnose the blistering skin diseases,especially when additional clinical findings such as Nikolski phenomena are not present.In addition,the sonographic characteristics show a high correlation with the well-known histologic findings of these diseases.2.The droplet digital PCR is superior to Taqman qPCR technology for the diagnosis of leprosy,which provides a new means for early diagnosis of leprosy cases,especially paucibacillary patients.3.The application of new technologies in dermatology still need further exploration,On the one hand,to expand the application field,further analysis of features and principle of existing imaging technology or molecular biology techniques are needed.On the other hand,as new technologies are emerging endlessly,every researcher should keep bold attempts and active explorations.