There is typically a low numbers of macrophages and inflammatory cells (although this is variable). Treatment
The standard treatment for PAP is whole-lung lavage and supportive care. Whole lung lavage is a procedure performed under general anesthesia, in which one lung is pumped with oxygen (ventilated lung), and the other lung (non-ventilated lung) is filled with a warm saline solution (up to 20 L) and drained, removing any proteinaceous effluent along with it. This is generally effective at improving PAP symptoms, often for a prolonged period of time. Other treatments still being studied include subcutaneous and inhaled GM-CSF, and rituximab, an intravenous infusion that works to stop the production of the autoantibodies responsible for autoimmune PAP. Lung transplantation has been performed in individuals with the various forms of PAP; however, this is often only used when all other treatment options have failed and significant lung damage has developed due to the risks, complications, or recurrence of PAP following transplantation. Epidemiology
The disease is more common in males and in tobacco smokers.In a recent epidemiologic study from Japan,  Autoimmune PAP has an incidence and prevalence higher than previously reported and is not strongly linked to smoking, occupational exposure, or other illnesses. Endogenous lipoid pneumonia and non-specific interstitial pneumonitis has been seen prior to the development of PAP in a child. History
PAP was first described in 1958 by the physicians Samuel Rosen, Benjamin Castleman, and Averill Liebow.
Pathology
Macroscopically, splenosis manifests as individual pieces of reddish-blue tissue with variable shape, which can be as few as one and as many as 300, mostly in the abdominal cavity, and varying in size from a few millimeters to as large as 12 cm. Due to the limited blood supply to these nodules, the typical size of splenic implants is usually less than 3 cm. The implants can be separate pieces or connect to other pieces of splenic tissue by a thin stem. Histologically, the regular spleen tissue is made up of red and white pulp, similar to the structure of an accessory spleen. Clinical presentation
About a decade commonly passes between the injury and the discovery of splenosis. As little as five months and as much as 32 years have been reported. Most people with splenosis have no symptoms, so the splenosis is discovered by chance through screening or in the process of diagnosing another disease. Some people experience symptoms, such as abdominal pain, intestinal obstruction, hemorrhage, or hydronephrosis. Tissue infarction due to limited blood supply can be a cause of symptomatic splenosis. Symptoms of splenosis affecting the thoracic cavity sometimes include hemoptysis or pleurisy. Diagnosis
A definitive diagnosis is often made through biopsy and histological examination of the tissue by a pathologist. Multiple implants of splenic tissue can mimic the appearance of some cancerous conditions. This can be clarified through diagnostic imaging (for example, ultrasound, CT scan, and MRI).