A Diagnosis on theLAM: Pulmonary Lymphangioleiomyomatosis Masquerading as Progressive Mediastinal Lymphadenopathy

Andrew Kuykendall, MD; Prudence Smith, MD; Jose Silva-Morales, MD; Joseph Garrett, MPH; Carla Moodie, PA-C; Eric Toloza, MD

INTRODUCTION: Mediastinal lymphadenopathy is usually diagnosed by computed tomography (CT) scan and has a broad differential diagnosis, including primary or metastatic neoplasia, acute infection, sarcoidosis, and chronic infection, such as Histoplasmosis or tuberculosis. Various mimickers of lymphadenopathy have been described, and their identification is vital to establish an accurate diagnosis, to minimize unnecessary diagnostic workup, and to provide appropriate therapy.

CASE PRESENTATION: We present a 46-year-old woman with history of pregnancy-associated chylothorax requiring pleuro-peritoneal shunt 19 years previously. More recently, she presented 3 months prior with back pain, exertional dyspnea, and left supraclavicular lymphadenopathy, without fever or night sweats. Her dyspnea worsened, and serial CT scans noted progressively enlarging mediastinal lymph nodes (LNs). Positron emission tomography (PET)-CT scan was compared to a PET-CT scan 5 years earlier and revealed extensive mediastinal lymphadenopathy as well as prevascular, paraortic, and retroperitoneal soft tissue masses with minimal to low fluorodeoxyglucose activity. Left supraclavicular LN biopsy revealed prominent smooth muscle with staining for desmin and smooth muscle actin, indicating a likely lymphangioma. She was referred for surgical evaluation of her mediastinal LNs. She underwent left video-assisted thorascopy, with extensive pleurolysis and pleural and posterior mediastinal biopsies. The presumed extensive posterior mediastinal LNs were found to be loculations of chylous fluid. Pleural and mediastinal biopsies were consistent with pulmonary lymphangiomyomatosis. She had no perioperative complications and was discharged home on postoperative day #2. She was treated with daily oral pazopanib, a tyrosine kinase and angiogenesis inhibitor.

DISCUSSION: Lymphangioleiomyatosis (LAM) is an uncommon gender-restricted disease characterized by progressive dyspnea on exertion, recurrent pneumothoraces, lymphadenopathy, chylous effusions, abdominal tumors, and characteristic thin-walled cysts on high resolution CT (HRCT)1. In our case, loculated chylous lakes mimicked a finding of progressive mediastinal lymphadenopathy, which, in addition to our patient’s gender and age, along with her lack of smoking history, weight loss, or infectious symptoms, led to an initial suspicion for lymphoma. However, her history of chylous effusion during child-bearing age resulted in concern for LAM. Surgical biopsy proved useful to confirm diagnosis in this atypical case.

CONCLUSIONS: Pulmonary LAM is rare, with classic presenting features occurring in a characteristic patient population. With nonspecific imaging features, maintaining high clinical suspicion is important to establish an accurate diagnosis.

Chest. 2014;146(4_MeetingAbstracts):354A. doi:10.1378/chest.1976158