Lipoid pneumonia

　　Lipoid pneumonia can be divided into exogenous and endogenous according to the different causes of the occurrence of lipoid pneumonia. Specifically, as follows.

　　Firstly, exogenous lipoid pneumonia:It is caused by the inhalation of vegetable, animal, or mineral oils, with liquid paraffin being the most common. Liquid paraffin nasal drops often drain into the lower part of the lung, and liquid paraffin as a laxative can be inhaled into both lungs if aspirated. Mineral oil has little irritability, does not cause a cough reflex when entering the bronchial tree through the pharynx, and can also impede the ciliary movement of the airway epithelium in the removal of inhaled oils.

　　Mineral oil is an inert substance that is not hydrolyzed in the body, emulsified rapidly in the lungs upon inhalation, engulfed by macrophages, and transported away through the lymphatic vessels; if there are residues, they can cause pulmonary fibrosis. Vegetable oils such as olive oil can be emulsified but cannot be hydrolyzed by pulmonary esterase, so they do not damage the lung, most of which are coughed up. Animal oils can be hydrolyzed by pulmonary esterase, releasing fatty acids, causing significant inflammatory reactions, and early inflammation and late fibrosis can coexist in the same lesion.

　　Secondly, endogenous lipoid pneumonia is also known as cholesterol pneumonia (cholesterol pneumonia):It is a complication of lung cancer, bronchiectasis, radiation therapy, and fibrosis secondary to systemic sclerosis or pneumoconiosis, etc., and can also occur in diseases such as fat embolism, pulmonary alveolar proteinosis, and lipodystrophy.

　　Lipoid pneumonia, in addition to its clinical manifestations, can also cause other diseases. Lipoid pneumonia can complicate with fat embolism and lipodystrophy, and severe cases may complicate with pulmonary heart disease, which should be highly emphasized by clinicians and patients.

　　Most patients with lipoid pneumonia are asymptomatic, and it is only noticed when an abnormality is found on a chest X-ray. Common symptoms include cough, dyspnea after exercise, and may include chest pain, hemoptysis, fever (often low-grade), chills, night sweats, and weight loss. Physical examination may show no signs, or there may be fever, tachypnea, and dullness on auscultation of the chest, with bronchial or bronchopulmonary rales or crackles, and the analysis of arterial blood gases may be normal. Hypoxemia may occur after exercise, and severe patients may have hypoxemia,低碳酸血症, and mild respiratory alkalosis. Pulmonary function tests show restrictive ventilatory dysfunction, decreased lung compliance, sputum examination shows macrophages with vacuoles of 5-50mm in diameter in the sputum, aggregated into clumps, showing deep orange-yellow when stained with Sudan, and extracellular small oil droplets with the same staining. Chest X-rays may show unilateral or bilateral infiltrative shadows, which are localized or diffuse in distribution, more common in the lower lungs, with visible air bronchograms. When fibrosis occurs, the lung volume decreases, with linear and nodular infiltrative shadows, and may also present as localized masses, resembling bronchogenic lung cancer.

　　Lipoid pneumonia seriously affects patients' daily lives, so it should be actively prevented. Exogenous lipoid pneumonia should focus on prevention, avoid using liquid paraffin drops in the nose and diarrhea, and people prone to the disease should pay special attention.

　　In the sputum of patients with lipoid pneumonia, macrophages can be seen with vacuoles of 5-50mm in diameter, aggregated into groups, and when Sudan stained, they appear deep orange-yellow, with similar stained extracellular small oil droplets, and an accelerated erythrocyte sedimentation rate.

　　X-ray chest films show unilateral or bilateral infiltrative shadows,呈局限性或弥散性分布，most commonly in the lower lungs, with visible airway bronchial signs. When fibrosis occurs, lung volume decreases, with linear and nodular infiltrative shadows, and there may also be localized mass shadows, resembling bronchogenic lung cancer. Pulmonary function tests show restrictive ventilatory dysfunction and decreased lung compliance.

　　Patients with lipoid pneumonia should pay attention to taking light and easily digestible foods in their diet, eat more fresh vegetables and fruits appropriately, drink more water, especially it is recommended to eat more foods such as white fruit, lily, white radish, lotus root slices, and at the same time, avoid eating cold, spicy, and stimulating foods, avoid smoking, drinking alcohol, drinking strong tea, and staying up late, and pay attention to resting more.

　　Guidance for patients with lipoid pneumonia to perform cough exercises for several days to promote the excretion of mineral oil. Exogenous lipoid pneumonia should focus on prevention, avoid using liquid paraffin (paraffin oil) drops in the nose and diarrhea, and people prone to the disease should pay special attention. There are also reports of effective treatment with corticosteroids. Endogenous cholesterol pneumonia is mainly treated by surgery, especially in cases that are difficult to differentiate from lung cancer.