The DL still fulfill histological criteria for lupus. In the absence of a precise histological diagnosis, thickening of basement membrane, hyperkeratosis, cellular infiltration, epidermal atrophy and elastosis are the most common features. Loss of melanocytes and the dermal fibrosis suggests that DL in cutaneous LE behave as post-inflammatory scars.

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Focal cortical dysplasia (FCD) is a highly epileptogenic cortical malformation with few treatment options. Here we generated human cortical organoids from patients with FCD type II. Using this human model, we mimicked some FCD hallmarks, such as impaired cell proliferation, the presence of dysmorphic neurons and balloon cells, and neuronal network hyperexcitability. Furthermore, we observed alterations in the adherens junctions zonula occludens-1 and partitioning defective 3, reduced polarization of the actin cytoskeleton, and fewer synaptic puncta. FCD cortical organoids showed downregulation of the small GTPase RHO A, a finding that was confirmed in brain tissue resected from these patients. Functionally, both spontaneous and optogenetically-evoked electrical activity revealed hyperexcitability and enhanced network connectivity in FCD organoids. Taken together, our findings suggest a ventricular zone instability in tissue cohesion of neuroepithelial cells, leading to a maturational arrest of progenitors or newborn neurons, which may predispose to cellular and functional immaturity and compromise the formation of neural networks in FCD.

5064 Introduction Livedoid vasculopathy is a rare skin disease caused by the extensive formation of microthrombi in dermis vessels, which leads to infarction and ulceration of the epidermis. The pathogenesis of livedoid vasculopathy is unknown, and hypercoagulation states have been implicated. Moreover, success using anticoagulation was reported in some patients. We hypothesized that decreased levels of ADAMTS13 activity and Von Willebrand factor (vWF) levels could contribute to the pathogenesis of local thrombus formation in livedoid vasculopathy. Objective Here we evaluated the levels of ADAMTS13 activity and vWF in patients with livedoid vasculopathy. Patients and methods Fourteen patients (93% female) with livedoid vasculopathy, median age of 41.5 years (22 - 48) were included in the study. All patients were evaluated for the presence of classical acquired and hereditary thrombophilia markers. In addition, vWF antigen levels (Elisa) and activity (collagen binding assays), as well as ADAMTS13 activity (evaluated by residual collagen binding) were evaluated. Results nine patients (64%) were carriers of the MTHFR C677T mutation (6 heterozygous and 3 homozygous); 1 patient was a carrier of factor V Leiden mutation, and 1 patient was a carrier of the FII G20210A mutation. None of the patients presented deficiency of antithrombin, protein C or S, and antiphospholipid antibodies were not identified in our study population. ADAMTS13 and VWF activities were normal in all patients. Median vWF antigen was 120.5U/dl (reference value of 40.0 - 232.0%), and vWF activity was 102.3% (reference value of 45.5 - 203.7%). ADAMTS13 activity was 138.9% (reference value of 56.0 - 227.2 %). Two patients had a history of thromboembolic diseases: one patient with 2 strokes and one patient with central retinal artery occlusion. Conclusion We show here that ADAMTS13 activity and vWF levels are not altered in patients with livedoid vasculopathy. The MTHFR C677T mutation is frequent in patients with livedoid vasculopathy but quantification of homocysteine levels is necessary to consider any relationship with this disease. Disclosures No relevant conflicts of interest to declare.

Sarcoidosis and tuberculoid leprosy (TL) are prototypes of granulomatous inflammation in dermatology, which embody one of the histopathology limitations in distinguishing some diseases. Recent advances in the use of nonlinear optical microscopy in skin have enabled techniques, such as second-harmonic generation (SHG), to become powerful tools to study the physical and biochemical properties of skin. We use SHG images to analyze the collagen network, to distinguish differences between sarcoidosis and TL granulomas. SHG images obtained from skin biopsies of 33 patients with TL and 24 with sarcoidosis retrospectively were analyzed using first-order statistics (FOS) and second-order statistics, such as gray-level co-occurrence matrix (GLCM). Among the four parameters evaluated (optical density, entropy, contrast, and second angular moment), only contrast demonstrated statistical significance, being higher in sarcoidosis (p ¼ 0.02; 4908.31 versus 2822.17). The results may indicate insufficient differentiating power for most tested FOS and GLCM parameters in classifying sarcoidosis and TL granulomas, when used individually. But in combination with histopathology (H&E and complementary stains, such as silver and fast acid stains), SHG analysis, like contrast, can contribute to distinguishing between these diseases. This study can provide a way to evaluate collagen distribution in granulomatous diseases.