A40-12 Reevaluation of Pulmonary Langerhans Cell Histiocytosis Following Retrospective Pathology Review

Abstract Pulmonary Langerhans cell histiocytosis (PLCH) is an inflammatory lung disease characterized by parenchymal Langerhans cell infiltration. In most patients with PLCH, the disease is isolated to the lung, but multisystem disease can be present. Differentiating between isolated PLCH and multisystem LCH is vital, as the treatment strategies vary considerably. Therefore, clinicians should maintain a high index of suspicion for extrapulmonary manifestations when evaluating patients with PLCH. A 31-year-old male presented to the emergency department (ED) with sudden-onset shortness of breath. Medical history was significant for recurrent mandibular osteomyelitis over the last 2 years and tobacco use. A right-sided pneumothorax was noted on chest x-ray, and a chest tube was placed and attached to a Heimlich valve. He was discharged with follow-up planned, but represented to the ED prior to follow-up. The Heimlich valve was found to be malfunctional, and computed tomography (CT) chest showed worsening pneumothorax, subcutaneous emphysema, and pneumomediastinum. CT also was concerning for PLCH. Chest tube was replaced with improvement in the pneumothorax. On day 6, patient underwent chemical pleurodesis. Given the CT findings concerning for PLCH, further evaluation focused on the patient’s history of osteomyelitis to assess for multisystem involvement. The patient had initially presented to a dentist with tooth pain 2 years prior to his admission, and failed several antibiotic courses, requiring extraction of the tooth. He was referred to oral and maxillofacial surgery and underwent debridement of the left mandible. A bone biopsy showed acute and chronic inflammation, and culture grew several bacteria consistent with oral flora. The patient completed a prolonged course of antibiotics but was still having jaw pain a year after the initial debridement. During his admission for pneumothorax, biopsies were requested from outside hospital for re-review. Cells that stained positive for CD1a, S100, and Langerin (Figure 1) were seen on biopsy, consistent with diagnosis of Langerhans cell histiocytosis. The patient was referred to hematology/oncology for management. In this patient, his disease was initially suspected to be isolated PLCH. However, after review of medical history, there was concern for possible multisystem LCH. This was confirmed after obtaining biopsy slides and re-reviewing with the new knowledge of his pulmonary disease. For management of this patient’s disease, initially only smoking cessation was recommended. By reevaluating his reported history of recurrent osteomyelitis of the jaw, the suspicion for multisystem LCH was heightened, leading to correct diagnosis and referral to hematology/oncology for chemotherapy. This abstract is funded by: None