[Granulomatous dermatoses]. / Granulomatöse Dermatosen.

The group of granulomatous dermatoses refers to a multitude of clinically different diseases, which are characterized by a histopathologically similar pattern of inflammation. The cause of granulomatous inflammatory reactions can be infections and also noninfectious stimuli, such as cell disintegration or foreign bodies. The aim of this immunological defence reaction is encapsulation in order to prevent further spread and delimitation from healthy tissue. This is histologically expressed as a granuloma in the sense of a circumscribed aggregation of histiocytes and multinucleated giant cells mostly in dermal connective tissue. The following can be histologically differentiated: sarcoid granuloma characterized by a sparse lymphocytic inflammatory infiltrate and tuberculous granuloma with central necrosis and denser lymphocytic inflammatory infiltrate. Neutrophilic granulocytes together with macrophages occur in suppurative granulomas and palisaded granulomas are characterized by peripherally arrayed macrophages.

Deep Learning Assisted Diagnosis of Onychomycosis on Whole-Slide Images.

BACKGROUND: Onychomycosis numbers among the most common fungal infections in humans affecting finger- or toenails. Histology remains a frequently applied screening technique to diagnose onychomycosis. Screening slides for fungal elements can be time-consuming for pathologists, and sensitivity in cases with low amounts of fungi remains a concern. Convolutional neural networks (CNNs) have revolutionized image classification in recent years. The goal of our project was to evaluate if a U-NET-based segmentation approach as a subcategory of CNNs can be applied to detect fungal elements on digitized histologic sections of human nail specimens and to compare it with the performance of 11 board-certified dermatopathologists. METHODS: In total, 664 corresponding H&E- and PAS-stained histologic whole-slide images (WSIs) of human nail plates from four different laboratories were digitized. Histologic structures were manually annotated. A U-NET image segmentation model was trained for binary segmentation on the dataset generated by annotated slides. RESULTS: The U-NET algorithm detected 90.5% of WSIs with fungi, demonstrating a comparable sensitivity with that of the 11 board-certified dermatopathologists (sensitivity of 89.2%). CONCLUSIONS: Our results demonstrate that machine-learning-based algorithms applied to real-world clinical cases can produce comparable sensitivities to human pathologists. Our established U-NET may be used as a supportive diagnostic tool to preselect possible slides with fungal elements. Slides where fungal elements are indicated by our U-NET should be reevaluated by the pathologist to confirm or refute the diagnosis of onychomycosis.

Anti-p200 pemphigoid: a novel autoimmune subepidermal blistering disease.

Anti-p200 pemphigoid is a recently defined autoimmune subepidermal blistering disease characterized by circulating and tissue-bound autoantibodies to a 200-kDa protein (p200) of the dermal-epidermal junction (DEJ). This DEJ constituent is thought to be important for adhesion of basal keratinocytes to the underlying dermis. While the exact identity of p200 remains unknown, it has been demonstrated to be immunologically and biochemically distinct from all major autoantigens of the DEJ, including bullous pemphigoid antigens 180 and 230, laminin 1, 5 and 6, alpha6beta4 integrin, and type VII collagen. Clinically, most reported cases present with tense blisters as well as urticarial papules and plaques, closely resembling bullous pemphigoid. Histopathological examination of lesional skin biopsies shows subepidermal split formation and superficial inflammatory infiltrate typically dominated by neutrophils. Immunopathologically, linear deposits of immunoglobulin (Ig)G and C3 are detected along the DEJ by direct immunofluorescence microscopy of perilesional skin. Indirect immunofluorescence microscopy of patients' sera on NaCl-split human skin demonstrates circulating IgG autoantibodies labeling the dermal side of the split. By immunoblotting, these autoantibodies recognize a 200-kDa protein of human dermis. Biochemical characterization of the p200 molecule revealed a noncollagenous N-glycosylated acidic protein with an isoelectric point of approximately 5.5. We present an overview of the pathogenesis, clinical features, diagnosis and treatment of this new disease entity.

[Syphilis maligna in an HIV-negative patient]. / Syphilis maligna bei einem HIV-negativen Patienten.

A 21-year-old patient with a history of drug addiction presented with generalized, centrally-ulcerated papules and haemorrhagic crusts. Initially, differential diagnostic considerations included pityriasis lichenoides et varioliformis acuta and syphilis. Biopsy and serological testing confirmed the latter diagnosis. Syphilis maligna is a rare form of secondary syphilis; symptoms include a papulonecrotic exanthem and general malaise with fevers and wasting. In the past the disease was described in connection with tuberculosis; today it is most often seen in association with HIV.