INTRODUCTION: Primary pulmonary lymphomas (PPL) are rare and are seldom considered in the initial differential diagnosis when a patient presents with a clinical picture of "non-resolving pneumonia". Even so, the majority of PPL are B-cell derived neoplasms. We report an unusual case of non-HIV related PPL of natural killer/T-cell origin presenting as non-resolving pneumonia.
CASE PRESENTATION: A 31 year old nonsmoking Egyptian male without significant past medical history presented to the hospital with shortness of breath, cough and low-grade fever of several weeks duration. He was diagnosed with community acquired pneumonia based on chest x-ray findings of bilateral alveolar infiltrates. Despite treatment with antibiotics, he clinically declined, and developed acute respiratory failure requiring mechanical ventilation. Systemic corticosteroids were added and antibiotics were broadened which improved his clinical status. He was then successfully extubated and discharged from the hospital after a few weeks. HIV test done during the hospitalization was negative. Over the next few weeks, he had recurrence of symptoms upon corticosteroid taper and was re-admitted to the hospital for progressive respiratory insufficiency. A chest CT scan revealed bilateral diffuse patchy lung parenchymal consolidation with air bronchograms without significant mediastinal or hilar lymphadenopathy. He failed to improve on empiric regimen of systemic corticosteroids and broad spectrum antibiotics. A fiber-optic bronchoscopy was non-diagnostic, following which a video-assisted thoracoscopic lung biopsy was performed. The surgical lung specimen showed atypical lymphocytic interstitial infiltrates. The immunohistochemical stains confirmed the diagnosis of NK/T-cell lymphoma. A total body PET imaging study showed abnormal uptake only in the lung fields with no hypermetabolic lymphadenopathy elsewhere in the body. A bone marrow biopsy was negative for lymphoma. The patient was treated with chemotherapy for a few months which resulted in radiographic resolution of lung infiltrates and successfully underwent an allogeneic hematopoietic stem cell transplant. Unfortunately, this was complicated by gastrointestinal graft-versus-host disease, cytomegalovirus (CMV) pneumonitis, and refractory thrombocytopenia. He expired from an intracranial hemorrhage approximately one year after initial presentation.
DISCUSSIONS: PPL are rare and represent only 0.5-1% of all primary lung malignancies and less than 1% of all cases of Non-Hodgkin's lymphoma. The diagnostic criteria of PPL usually include: 1) involvement of the lung without evidence of mediastinal adenopathy 2) no previous diagnosis of extrathoracic lymphoma 3) no evidence of extrathoracic lymphoma or lymphatic leukemia at the time of diagnosis of PPL or for three months thereafter. PPL are typically of B-cell linage and thought to arise from the bronchial mucosal associated lymphoid tissue (BALT). Very few cases of PPL of T-cell origin have been reported in the literature with NK/T-cell lymphoma being rarer still. Such cases often exhibit aggressive metastatic potential that may lead to a rapid clinical decline. Our patient presented clinically as "non-resolving pneumonia" with radiographs illustrating diffuse lung parenchymal consolidation. The absence of lymphadenopathy and negative bone marrow specimens support a primary pulmonary origin in this case. Following chemotherapy, this patient's clinical status improved and the pulmonary infiltrates resolved; unfortunately he expired from complications of hematopoietic stem cell transplantation.
CONCLUSION: The differential diagnosis of lung parenchymal consolidation presenting as "non-resolving" pneumonia is vast. However, in reporting this case, we bring awareness that NK/T-cell lymphoma may present as a primary pulmonary tumor. Early suspicion, biopsy and appropriate chemotherapy regimens are necessary for this otherwise aggressive lymphoma.
DISCLOSURE: Brian Davis, No Financial Disclosure Information; No Product/Research Disclosure Information