Uncommon, except in lower socioeconomic classes, this typically affects adolescents and young adults, especially in institutions, armed forces, etc., or people with HIV/AIDS. The disease has occurred in epidemic-like patterns, but it is not contagious. History
Necrotizing ulcerative gingivitis has been observed for centuries. Xenophon observes sore mouth and foul smelling breath in Greek soldiers in the 4th century BC. Hunter describes the clinical features of ANUG in 1778, differentiating it from scurvy (avitaminosis C) and chronic periodontitis. Jean Hyacinthe Vincent, a French physician working at the Paris Pasteur Institute describes a fusospirochetal infection of the pharynx and palatine tonsils, causing "ulcero-membranous pharyngitis and tonsillitis", which later became known as Vincents angina. Later in 1904, Vincent describes the same pathogenic organisms in "ulceronecrotic gingivitis". Vincents angina is sometimes confused with NUG, however the former is tonsillitis and pharyngitis, and the latter involves the gums, and usually the two conditions occur in isolation from each other. The term trench mouth evolved because the disease was observed in front line soldiers during World War I, thought to be a result at least partly because of extreme psychologic stress they were exposed to. The same condition was appearing in civilians during periods of bombing raids, who were away from the front line, and who had relatively good diets during wartime due to rationing, so it is assumed that psychologic stress was the significant causative factor. It has also been associated with high tobacco use in the army.
Peliosis hepatis is an uncommon vascular condition characterised by multiple, randomly distributed, blood-filled cavities throughout the liver. The size of the cavities usually ranges between a few millimetres and 3 cm in diameter. In the past, it was a mere histological curiosity  occasionally found at autopsies, but has been increasingly recognised with wide-ranging conditions from AIDS to the use of anabolic steroids. It also occasionally affects spleen, lymph nodes, lungs, kidneys, adrenal glands, bone marrow, and other parts of gastrointestinal tract.Peliosis hepatis is often erroneously written "peliosis hepatitis", despite its not being one of the hepatitides. The correct term arises from the Greek pelios, i.e. discoloured by extravasated blood, livid, and the Latinized genitive case (hepatis) of the Greek hepar, liver. Presentation
Disease associations
Infections: HIV, bacillary peliosis (caused by genus  Bartonella, bacteria responsible for cat-scratch disease which are identified histologically adjacent to the peliotic lesions), Staphylococcus aureus
Chronic conditions:  End stage kidney failure, kwashiorkor, tuberculosis, and other chronic infections
Malignancy: Monoclonal gammopathies (multiple myeloma and Waldenströms macroglobulinemia), Hodgkin disease, malignant histiocytosis, seminoma, hepatocellular adenoma, and hepatocarcinoma
Kidney transplants:  It can be found in up to 20% patients, can be related to azathioprine or cyclosporine use, and may be associated with increased risk of transplant rejection. Drugs and toxins: Corticosteroids, androgens, azathioprine, tamoxifen

Pathophysiology
The pathogenesis of peliosis hepatis is unknown.