Pulmonary complications following bone marrow transplantation are common - ranging from infectious pneumonias to venous occlusive disease. Determining the correct diagnosis depends on integrating clinical data, tissue pathology, and radiographic patterns.
A twenty-nine year old African American male presented to the emergency room 45 days after receiving an autologous bone marrow transplant (BMT) for refractory non Hodgkin’s lymphoma; he had received BCNU, etoposide, cytarabine and melphalan (BEAM) chemotherapy prior to transplant. His complaints centered around dyspnea on minimal exertion progressing to dyspnea at rest over a one week time period; he denied cough, sputum production, or dyspnea with change in position. His vitals were remarkable for tachypnea with a rate in the thirties, temperature of ninety-nine degrees Fahrenheit, pulse rate of one hundred thirty, and requirement of a non-rebreather to keep his oxygen saturations above ninety percent. Pulmonary exam was remarkable for inspiratory crackles at the bases bilaterally and velcro rales of the apices bilaterally. The rest of the physical exam was notable for a high work of breathing, skin changes from prior radiation to his neck/mantle area, and for the absence of edema or jugular venous distention. The patient was admitted to the intensive care unit where bronchoscopy was performed and broad spectrum antibiotics, antivirals and antifungals were started. Bronchoscopy was remarkable for clear return from multiple bronchoalveolar lavages. Samples were sent for multiple studies including cytology and cultures (viral, acid fast, fungal, and bacterial.) The patient was intubated for respiratory fatigue on the second hospital day and afterwards a contrast chest CT was performed which demonstrated multilobar infiltrates and evidence of radiation fibrosis in the apices. A wedge biopsy from the lingula was performed on the third hospital day;pathology returned as diffuse alveolar damage. Cultures and cytology from the lung biopsy were also negative for infectious pathogens or malignant cells.
Pulmonary infiltrates after BMT are usually divided into those that occur in the first hundred days post transplant, and those that occur beyond that time frame. They are further divided into infectious and non-infectious etiologies. Infectious pulmonary infiltrates result from a multitude of causes including bacteria, viruses (especially respiratory syncytial virus, herpes simplex, and cytomegalovirus), fungi, and pneumocystis. Non-infectious causes include pulmonary edema, diffuse alveolar hemorrhage, radiation pneumonitis, mediastinal emphysema, cytolytic thrombi, acute graft versus host disease, and idiopathic pneumonia syndrome (IPS.) The patient’s lung biopsy was only remarkable for diffuse alveolar damage - no infections, no venoocclusive changes, no signs of malignancy. Our patient had two negative cultures from his lungs - from bronchoscopy and open lung biopsy. He had not received any radiation therapy in conjunction with his bone marrow transplant. Idiopathic pneumonia syndrome was formally defined by a 1993 NHLBI forum as diffuse lung injury (evident by CT and/or altered pulmonary physiology) occurring after BMT for which an infectious etiology is not identified. The patient described met these criteria. Treatment with steroids at 2mg/kg/day was started after the pathology returned and cultures from the lung biopsy remained negative for over three days. Improvements in the patient’s chest radiograph and in his pO2 to fiO2 ratio were dramatic.
The diagnosis of idiopathic pneumonia syndrome confers a poor prognosis - the one-year mortality is over eighty percent. The mechanism of injury also continues to be poorly understood but is thought to be the result of multiple insults - pretreatment chemotherapy, T lymphocyte activation, and oxidative stresses. Treatment with high dose steroids is still regarded as the standard of care by many experts - although the benefit from the treatment is controversial. Investigational treatments with tumor necrosis factor blockers and antioxidants are currently being studied.
C.E. Grossman, None.