INTRODUCTION: Idiopathic interstitial pneumonias (IIP) are an uncommon cause of chronic cough. Lymphoid interstitial pneumonia (LIP) is a very rare diagnosis, found in only about 1% of biopsies performed for interstitial lung disease. LIP is manifested as a lymphoplasmacytic infiltration of the alveolar spaces and interstitium. Though the etiology of this process is unknown, it is most commonly associated with connective tissue disease and immunodeficiency. We present a case of LIP in a 43-year-old male presenting with chronic cough.
CASE PRESENTATION: A 43 year-old non-smoking male presented to our clinic for evaluation of a chronic, dry cough of two months duration. He denied sputum production, fever, allergies, gastrointestinal reflux, and wheezing. Previous treatment included multiple courses of antibiotics, with no improvement in symptoms. Vital signs and physical exam were normal. Chest x-ray showed no acute cardiopulmonary process. Initial spirometry revealed a mild reduction in FVC without bronchodilator response. He was started on empiric treatment for chronic cough including an antihistamine and proton pump inhibitor. He returned six weeks later for follow-up with no improvement in his cough. Repeat spirometry included lung volumes consistent with a moderate restrictive pattern. A high-resolution chest CT scan revealed basilar subpleural interlobular septal thickening and ground glass opacities. A bronchoscopy, with transbronchial biopsies and bronchoalveolar lavage, was performed. Pathology showed a focal lymphoid follicle, with nonspecific, mixed inflammation on BAL. The patient was referred for surgical lung biopsy, which revealed prominent lymphoplasmacytic infiltrates with lymphoid follicle formation, consistent with lymphoid interstitial pneumonia. The patient subsequently developed symptoms consistent with an autoimmune myositis, though definitive diagnosis of his rheumatologic disease is pending at the time of this submission.
DISCUSSION: Lymphoid Interstitial Pneumonia (LIP) is a rare condition that has a variable clinical course. It was first described in 1969 and classified as an idiopathic interstitial pneumonia. LIP falls within a spectrum of disease ranging from follicular bronchiolitis to malignant lymphoma. LIP is characterized on pathology by diffuse, polyclonal lymphoid cell infiltrates that invade the interstitium and surround the airways. CT scan commonly shows thickened bronchovascular bundles, nodules, cysts and ground-glass opacities. It is most frequently associated with autoimmune disorders, with Sjogren syndrome being the most common. Systemic immune deficiencies are also known causes, specifically HIV infection and common variable immunodeficiency. LIP tends to be female predominant with a mean age at diagnosis of 52-56 years. There is no race predominance, although most HIV-positive adults with LIP are African-American, and most HIV-negative adults are Caucasian. LIP is common in HIV-infected children, (16-50%), and is considered an AIDS-defining condition. While evidence of LIP can be seen on transbronchial biopsies, open lung biopsy is required for definitive diagnosis. It is typically treated with high-dose oral steroids, however the response is unpredictable. The clinical course is highly variable, ranging from complete resolution to death. Older studies showed a high transformation rate to malignant lymphoma (approximately 30%), but subsequent studies suggested that the number was likely closer to 5%.
CONCLUSIONS: Chronic cough is a common presenting symptom evaluated by pulmonary physicians. Though cough is most frequently attributed to conditions such as asthma, gastroesophageal reflux and upper airway cough syndrome, other less common etiologies should be considered if initial therapy for these conditions is unsuccessful. Using an algorithmic approach, additional testing, targeted by history, exam and spirometry findings, may be useful. In the case of our patient, a chest CT was performed to evaluate cough in the setting of progressive restriction. An interstitial abnormality not appreciated on chest x-ray was found, which prompted biopsy and ultimately led to the diagnosis of this unusual interstitial process. The exact incidence and prevalence rates of LIP are largely unknown, as it occurs so infrequently.
Reference #1 Swigris, J. J. "Lymphoid Interstitial Pneumonia: A Narrative Review." Chest 122.6 (2002): 2150-164.
Reference #2 Cha, S-I. "Lymphoid Interstitial Pneumonia: Clinical Features, Associations and Prognosis." European Respiratory Journal 28.2 (2006): 364-69. Print.
DISCLOSURE: The following authors have nothing to disclose: Allison Buel, Douglas Frenia, Michael Van de Kieft
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