Case of Pulmonary Langerhans-Cell Histiocytosis in 40-year-old
A 40-year-old male with a history of smoking reported to the emergency room with a 2-week history of cough, dyspnea, night sweats, and left-sided pleuritic chest pain. The physical examination revealed reduced breath sounds over the left lung fields. A chest radiograph (Panel A) revealed a significant pneumothorax on the left side as well as interstitial infiltrates in both lungs. Chest-tube thoracostomy was used to treat the pneumothorax. Following computed tomography of the chest, several cysts and nodules were found, mostly in the upper and intermediate lung fields, with the costophrenic angles spared (Panel B).
Transbronchial lung biopsy was carried out. Histopathological examination revealed a lymphocytic lung infiltrate with thickening of the interalveolar septum, eosinophils, and big cells with foamy cytoplasm and large nuclei (Panel C). S-100 protein, CD1a, placental acid phosphatase, and langerin immunohistochemical staining were all positive. The patient was diagnosed with pulmonary Langerhans-cell histiocytosis. Additional testing found no signs of systemic histiocytosis. BRAF testing was not carried out. The patient was encouraged to quit smoking, and a prednisone tapering dose was prescribed. At the 6-month check-up, the patient had quit smoking, was still on low-dose prednisone, and his symptoms had subsided.
Pulmonary Langerhans-Cell Histocytosis
Also known as eosinophilic granuloma of the lung, pulmonary Langerhans cell granulomatosis, and pulmonary histiocytosis X, is a rare cystic interstitial lung disease that usually affects young adults. It is caused by a myeloid dendritic cell dysfunction. There is no evidence of an occupational or regional propensity, however nearly all affected individuals have a history of current or prior cigarette smoking. As a result, cigarette smoke is suggested to be a factor.
The pathogenesis, clinical manifestations, diagnosis, and management of PLCH will be discussed in this article. A basic overview of Langerhans cell histiocytosis is offered separately, covering the more prevalent extrapulmonary symptoms of this illness.
Epidemiology
Although the exact incidence and prevalence of PLCH are unknown, it is rare. It is believed that PLCH accounts for 3 to 5% of adult diffuse parenchymal lung disease. The frequency is determined by the prevalence of cigarette smoking in the population, as more than 90% of PLCH patients smoke. White people are more likely to be affected than Black people.
A study from Japan underlined the rarity of the diagnosis, with frequency estimates of 0.27 per 100,000 in males and 0.07 per 100,000 in females. Similarly, a survey from an Italian speciality lung disease centre discovered 40 occurrences over a 10-year period.
The age of onset is greatest between the ages of 20 and 40. In general, males and females are equally affected, however, females tend to present at a later age.
Cigarette smoking and genetic factors
There is compelling evidence showing a link between cigarette smoking and PLCH in adults. The vast majority (> 90%) of adult patients who develop PLCH smoke cigarettes or have been exposed to significant second-hand smoke. The link between cigarette smoking and PLCH in children is less obvious, while it has been observed that smoking in adolescence can trigger PLCH in young adults with a history of non-pulmonary childhood LCH. Quitting smoking may result in total or partial remission of lung lesions. PLCH is distinguished by substantial peribronchial inflammatory alterations, implying that an inhaled irritant, such as cigarette smoke, has injured the tiny airways.
Macrophage recruitment and buildup surrounding tiny airways, interstitium, and distal air spaces is a critical characteristic of several smoking-induced lung disorders, including PLCH. A perplexing and unsolved subject concerns the observation that only a tiny percentage of smokers acquire PLCH, implying a role for endogenous host variables or additional external factors (a second hit). Smokers with PLCH may experience an amplified inflammatory response induced by tobacco smoke (and possibly other factors), which activates multiple cell types in the lung, including epithelial and immune cells, resulting in a vicious cycle of inflammation, tissue injury, and tissue remodelling.
Source: NEJM
