Conventional light microscopy (CLM) has classically been the basic tool to teach histology and pathology. In recent years, whole-slide imaging (WSI), which consists of generating a high-magnification digital image of an entire histological glass slide, has emerged as a useful alternative to CLM offering a myriad of opportunities for education. Navigation through the digitized slides closely simulates viewing glass slides with a microscope and is also referred to as virtual microscopy. WSI has many advantages for education. Students feel more comfortable with its use, and it can be used in any classroom as it only requires a computer with Internet access and it allows remote access from anywhere and from any device. WSI can be used simultaneously by a large number of people, stimulating cooperation between students and improving the interaction with the teachers. It allows making marks and annotations on specific fields, which enable specific directed questions to the teacher. Finally, WSI supports are cost-effective compared with CLM. Consequently, WSI has begun to replace CLM in many institutions. WSI has shown to be an extremely useful tool for undergraduate education (medical, dental and veterinary schools), for the training of residents of pathology, tele-education and in tumor boards.

BAckgRoundFor over half a century, clinicians and pathologists have recognized a group of pulmonary diseases associated with an accumulation of lymphoid follicles in the walls of bronchi and bronchioles. This entity was first described in patients with bronchiectasis, a disease characterized by extensive airway mural inflammation, where lymphocytic hyperplasia in the walls of small airways formed part of the inflammatory picture. However, in a group of patients, pathologists were able to confirm that sub-epithelial accumulation of lymphoid follicles was the primary pathology affecting the bronchioles [1]. These enlarged follicles would often distort the architecture of the bronchial tree, merely due to their size, projecting into the bronchial lumen and causing partial bronchial and bronchiolar obstruction.In 1947, the first reference to this entity was made by Engel et al., who coined the term "nodal bronchiolitis", describing thickened bronchioles, with well formed lymphoid follicles in their walls in the absence of a diffuse inflammatory infiltrate [2].In 1952, Whitewall studied 200 consecutive lung specimens mainly from lobectomies and pneumonectomies of patients with advanced bronchiectasis. He described this feature as "follicular bronchiectasis", where the most prominent microscopic finding was an extensive formation of lymphoid follicles and lymph nodes in the walls of affected bronchi and bronchioles [1].In 1979, Epler et al., described an association between bronchiolitis and the administration of D-penicillamine in 2 patients with rheumatoid arthritis and eosinophilic fasciitis. The chronic inflammatory bronchiolar disorder seen was characterized by extensive proliferation of lymphoid tissue, occurring as follicles in the bronchiolar walls and was given the name "follicular bronchiolitis" (FB) [3].Currently, FB is classified as one of the non-neoplastic (reactive) pulmonary lymphoid disorders in a group known as the lymphoproliferative pulmonary diseases (LPDs) [ ABstRActFollicular bronchiolitis (FB) also known as hyperplasia of the bronchial associated lymphoid tissue (BALT), or bronchiolar nodular lymphoid hyperplasia, is an entity characterized by the development of lymphoid follicles with germinal centers in the walls of small airways. FB is thought to be caused by antigenic stimulation of BALT, followed by a polyclonal lymphoid hyperplasia. It is currently classified as one of the reactive pulmonary lymphoid disorders in a group known as the lymphoproliferative pulmonary diseases (LPDs).FB is a pathological diagnosis that can be seen in several clinical settings, including connective tissue diseases, immunodeficiency states, autoimmune diseases, infections, obstructive airway diseases, as well as several types of interstitial lung diseases (ILDs).Its characteristics need to be carefully identified and differentiated from other closely related diseases in the group of LPDs due to significant differences in treatment and prognosis. Lymphoproliferative Pulmonary diseases (LPds)Reactive / of lymphoi...

AimsExperience in the use of whole slide imaging (WSI) for primary diagnosis in pathology is very limited. We aimed to determine the accuracy of interpretation of WSI compared with conventional light microscopy (CLM) in the diagnosis of routine gynaecological biopsies.MethodsAll gynaecological specimens (n=452) received over a 2-month period at the Department of Pathology of the Hospital Clinic of Barcelona were analysed blindly by two gynaecological pathologists, one using CLM and the other WSI. All slides were digitised in a Ventana iScan HT (Roche diagnostics) at 200×. All discrepant diagnoses were reviewed, and a final consensus diagnosis was established. The results were evaluated by weighted κ statistics for two observers.ResultsThe level of interobserver agreement between WSI and CLM evaluations was almost perfect (κ value: 0.914; 95% CI 0.879 to 0.949) and increased during the study period: κ value 0.890; 95% CI 0.835 to 0.945 in the first period and 0.941; 95%; CI 0.899 to 0.983 in the second period. Major discrepancies (differences in clinical management or prognosis) were observed in 9 cases (2.0%). All discrepancies consisted of small lesions (8 high grade squamous intraepithelial lesions of the uterine cervix, one lymph node micrometastasis of an ovarian carcinoma) underdiagnosed or missed in the WSI or the CLM evaluation. Discrepancies with no or minor clinical relevance were identified in 3.8% of the biopsies. No discrepancy was related to the poor quality of the WSI image.ConclusionsDiagnosis of gynaecological specimens by WSI is accurate and may be introduced into routine diagnosis.

Rapid advances in informatics and technological improvements have led to the development of high-throughput whole-slide imaging (WSI) scanners able to produce high-quality digital images, which allow achieving a correct diagnosis of the biopsies using virtual viewers. This technology is currently prepared to be introduced in the departments of pathology for routine diagnosis. The aim of this review is to analyze the current evidence regarding the use of WSI in primary or routine diagnosis in the different subspecialties of pathology. An increasing number of studies have shown almost perfect inter- and intraobserver agreement between the diagnoses obtained with WSI and the classical diagnoses based on conventional light microscopy. The only exception seems to be cytology, which still requires some technological development. Although validation studies are needed in some areas of pathology, growing evidence indicates that WSI is a reliable tool for routine diagnosis. Pathologists have a positive perception of the ergonomics of the workstations, the low magnification of WSI and the possibility of making annotations and measurements. WSI can be used from any device and anywhere, thereby providing great opportunities for teleconsultation. New technologies such as the recognition of histopathology patterns using image analysis may facilitate diagnosis and improve the reproducibility among pathologists in the future.