Diffuse large B-cell lymphoma associated with chronic inflammation
Diffuse large B-cell lymphoma associated with chronic inflammation (DLBCL-CI) is an Epstein–Barr virus-associated lymphoproliferative disease arising in persons with a long and persistent history of chronic inflammation. The diseases lesions consist of large, mature-appearing B-cells infiltrating the lungs pleura and nearby tissues. Most cases have occurred in patients who were given a pneumothorax (i.e. therapeutic introduction of air into the chest cavity in order to collapse and thereby "rest" the lung) to treat pulmonary tuberculosis that had progressed to a pyothorax (i.e. pus in the pleural cavity). Fibrin-associated large B-cell lymphoma (FA-DLBCL), often considered a sub-type of DLBCL-CI, is an infiltration of large neoplastic B-cells and fibrin affix to a prosthesis (e.g., cardiac valve, orthopaedic device) or accumulate within a hydrocele, pseudocyst, cardiac myxoma, or chronic subdural hematoma. The B-cells in these lesions are often but not always infected with the Epstein–Barr virus. DLBCL-CI occurring in cases of pleural empyema (sometimes termed pyothorax-associated lymphoma, i.e. PAL) is an aggressive lymphoma with a five-year overall survival rate of 20–35%; FA-DLBCL, when involving the heart (e.g. occurring on myxommas or prosthetic valves) or vasculature structures (e.g. on thrombus-laden vascular grafts), may involve life-threatening cardiovascular complications, particularly strokes. Outside of these complications, however, DLBCL-CI usually has a highly favorable outcome. Lymphomatoid granulomatosis
Lymphomatoid granulomatosis (LYG) is a DLBCL in which large, atypical B-cells with immunoblastic or Hodgkin disease-like features that are infected by the Epstein-Barr virus center around and destroy the microvasculature.
Cause
The most common causative organisms are (often intracellular living) bacteria:
Chlamydia pneumoniae
Mild form of pneumonia with relatively mild symptoms. Chlamydia psittaci
Causes psittacosis. Coxiella burnetii
Causes Q fever. Francisella tularensis
Causes tularemia. Legionella pneumophila
Causes a severe form of pneumonia with a relatively high mortality rate, known as legionellosis or Legionnaires disease. Mycoplasma pneumoniae
 Usually occurs in younger age groups and may be associated with neurological and systemic (e.g. rashes) symptoms.Atypical pneumonia can also have a fungal, protozoan or viral cause.In the past, most organisms were difficult to culture. However, newer techniques aid in the definitive identification of the pathogen, which may lead to more individualized treatment plans. Viral
Known viral causes of atypical pneumonia include respiratory syncytial virus (RSV), influenza A and B, parainfluenza, adenovirus, severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), COVID-19
and measles. Diagnosis
Chest radiographs (X-ray photographs) often show a pulmonary infection before physical signs of atypical pneumonia are observable at all. This is occult pneumonia. In general, occult pneumonia is rather often present in patients with pneumonia and can also be caused by Streptococcus pneumoniae, as the decrease of occult pneumonia after vaccination of children with a pneumococcal vaccine suggests.Infiltration commonly begins in the perihilar region (where the bronchus begins) and spreads in a wedge- or fan-shaped fashion toward the periphery of the lung field. The process most often involves the lower lobe, but may affect any lobe or combination of lobes. Epidemiology
Mycoplasma is found more often in younger than in older people. Older people are more often infected by Legionella.