Paracicatricial
Paracicatricial emphysema, also known as irregular emphysema, is seen next to areas of fibrosis (scarring) as large spaces. The scarring is most often a result of silicosis, granulomatous  infection, tuberculosis, or pulmonary infarction. It can be difficult to differentiate from the honeycombing of pulmonary fibrosis. HIV associated
Classic lung diseases are a complication of HIV/AIDS with emphysema being a source of disease. HIV is cited as a risk factor for the development of emphysema, and COPD regardless of smoking status. Around 20 percent of those with HIV have increased emphysematous changes. This has suggested that an underlying mechanism related to HIV is a contributory factor in the development of emphysema. HIV associated emphysema occurs over a much shorter time than that associated with smoking; an earlier presentation is also seen in emphysema caused by alpha-1 antitrypsin deficiency. Both of these conditions predominantly show damage in the lower lungs which suggests a similarity between the two mechanisms. Alpha-1 related
Emphysema may develop in some people with alpha-1 antitrypsin deficiency, the only genotype of chronic obstructive pulmonary disease. This usually occurs a lot earlier, as does HIV associated emphysema than other types. Ritalin lung
The intravenous use of methylphenidate, commonly marketed as Ritalin and widely used as a stimulant drug in the treatment of attention deficit hyperactivity disorder, can lead to emphysematous changes known as Ritalin lung. The mechanism underlying this link is not clearly understood. Ritalin tablets contain talc as a filler, and these need to be crushed and dissolved for injecting.
Leukoencephalopathy can develop from long-term treatment of methotrexate even at low doses. In contrast to intravenous methotrexate for cancer patients, leukoencephalopathy induced by orally taken methotrexate may be associated with cognitive dysfunction and even death.Oxycodone is the main active ingredient in various oral pain relief medications. High doses of opiates such as oxycodone can lead to leukoencephalopathy. The activity of various opioid and nociceptive receptors appear to play a role in the disease; however, the exact mechanism remains unknown.Metronidazole, an antibiotic used to treat anaerobic and protozoal infections, has been known at high doses to produce neurologic symptoms associated with toxic leukoencephalopathy. Other
Toxic leukoencephalopathy may also result from carbon monoxide poisoning, ingestion of methanol, ingestion of ethylene, toluene toxicity, ethanol poisoning, ingestion of methylenedioxymethamphetamine (MDMA or "ecstasy"), or ingestion of paradichlorobenzene, which is a toxic agent in mothballs. Diagnosis
Due to advances in MRI, this neurological disorder has been characterized more successfully in more recent years. MRI can aid in the detection of injured brain tissue; however, the severity and extent of the damage demonstrated by imaging does not always reflect patient clinical status. Toxic leukoencephalopathy encompasses the degeneration of white matter tracts devoted to higher cerebral function; however, white matter can appear normal until the disease has progressed more intensely. Toxic leukoencephalopathy-related damage to central nervous system (CNS) white matter, typically of the periventricular nucleus, and other structures in the brain is often bilateral and symmetric.