Pulmonary Langerhans cell histiocytosis presenting as a solitary nodule

Pulmonary Langerhans Cell Histiocytosis: An Unusual Differential for a Solitary Lung Nodule

Background

Pulmonary Langerhans cell histiocytosis (LCH) commonly presents as bilateral reticulonodular and cystic lung changes on chest imaging. Isolated lung nodule presentation is rare. Case Presentation. Our patient was an elderly male and an active smoker, who was referred to the pulmonology clinic for an incidental 19 mm lung nodule seen on a chest CT scan. A CT-guided transthoracic needle biopsy was performed to rule out malignancy. The biopsy sample showed marked inflammatory infiltrate with abundant eosinophils and epithelioid histiocyte-like cells suggestive of Langerhans cell histiocytosis. Antibodies against CD1a and Langerhans were positive which confirmed the diagnosis. During follow-ups, the patient had reduced smoking, and the lung nodule had decreased in size to 14 mm.

Conclusion

An isolated lung nodule in a patient with a smoking history always warrants a malignancy workup. Characteristic pathological findings with immunostaining are necessary to differentiate pulmonary LCH in these cases. Failure to perform immunostaining in such cases may lead to missing this vital diagnosis.

Pulmonary Langerhans Cell Histiocytosis Presenting as a Solitary Pulmonary Nodule on a Lung Cancer Screening CT

Pulmonary Langerhans cell histiocytosis (PLCH) is a rare inflammatory condition that mostly affects lungs in smokers. On imaging, it usually presents as multiple, upper lobe predominant, solid, and cavitary nodules, but presentation as solitary pulmonary nodule (SPN) is rare. We describe a case of SPN seen on low-dose lung cancer screening CT (LDCT) that was FDG avid on PET/CT. Given concern for malignancy, lobectomy was planned if intraoperative frozen section was consistent with malignancy. Lobectomy was performed based on frozen section; however, on formal pathology review, the nodule was ultimately found to be PLCH. This case illustrates an atypical presentation of PLCH as a solitary nodule. Furthermore, it helps demonstrate how rare etiologies (like PLCH) may be more frequently encountered and should be considered in the differential diagnosis for solitary lung nodules, especially in the era of lung cancer screening.

Obstructing tracheal pulmonary Langerhans cell histiocytosis

Pulmonary Langerhans cell histiocytosis, also known as eosinophilic granuloma, is an uncommon interstitial lung disease. A solitary nodule, usually parenchymal, may rarely be the only manifestation of the disease. We describe a case of Langerhans cell histiocytosis presenting as an obstructing tracheal lesion in a 55-year-old woman. Following complete resection of the lesion via flexible bronchoscopy, full recovery was achieved. This case represents a unique cause for tracheal obstruction, as well as an unreported manifestation of pulmonary Langerhans cell histiocytosis.

From the Archives of the AFIP

Pulmonary Langerhans cell histiocytosis (PLCH) is an isolated form of Langerhans cell histiocytosis that primarily affects cigarette smokers. PLCH is characterized by peribronchiolar proliferation of Langerhans cell infiltrates that form stellate nodules. The nodular lesions frequently cavitate and form thick- and thin-walled cysts, which are thought to represent enlarged airway lumina. PLCH lesions display temporal microscopic heterogeneity, with progression from dense cellular nodules to apparently cavitary nodules to increasing degrees of fibrosis that may extend along alveolar walls. In advanced cases, fibrotic scars are surrounded by enlarged, distorted air spaces. Affected patients are typically young adults who often present with cough and dyspnea. The characteristic radiographic features of PLCH are bilateral nodular and reticulonodular areas of opacity that predominantly involve the upper and middle lung zones with relative sparing of the lung bases. High-resolution computed tomography (CT) shows nodules and cysts in the same distribution and allows a confident prospective diagnosis of PLCH in the appropriate clinical setting. In typical cases, a predominantly nodular pattern is seen on CT scans in early phases of the disease, whereas a cystic pattern predominates in later phases. The radiologic abnormalities may regress, resolve completely, become stable, or progress to advanced cystic changes. Treatment consists of smoking cessation, but corticosteroid therapy may be useful in selected patients. Chemotherapeutic agents and lung transplantation may be offered to patients with advanced disease. The prognosis of PLCH is variable with frequent regression, stabilization, or recurrence of disease that does not correlate with cessation or continuation of smoking.