Case Presentation: 16 year old male presented with respiratory distress for 4 days. Past medical history included obesity, obstructive sleep apnea, mild intermittent asthma (no history of asthma hospitalizations), and sickle cell trait. Patient developed respiratory distress 4 days prior to presentation and was taking albuterol about 6-8 times a day with some relief. Notably, his mom had recently started smoking indoors and he had not used his prescribed CPAP for 2 years. Patient had no recent doctor visits, other than one for abdominal pain diagnosed as constipation. In his doctor’s office he was hypoxic to 78% on room air. He was transported to the emergency room and was started on continuous duoneb. On exam he was tachycardic, tachypnic, hypertensive, saturating in the low 90s on 12 L/min via facemask, obese (BMI of 53), uncomfortable but able to speak in full sentences. Respiratory exam had equal air movement bilaterally, but diminished in the bases without wheezing or rhonchi. Exam was noted to be limited by body habitus. He was treated with bronchodilators, IV magnesium, and steroids. He tolerated gradual reduction of respiratory support over the next couple days with weaning of bronchodilators from continuous to 4 times a day and weaning of supplemental oxygen to room air. Then he had a sudden onset of shortness of breath and hypoxia with saturation of 63% on room air. Repeat chest x-ray was similar to prior x-rays with persistent patchy bibasilar and perihilar opacities. At this time, the case was re-examined. In retrospect, his history of no significant asthma flares and absence of wheezing on exam, did not fit with an asthma etiology for his respiratory distress, and the differential was broadened. Due to concern for pulmonary embolism a lower extremity doppler was obtained and revealed a right external iliac deep vein thrombosis. Chest CT revealed a saddle embolism of his pulmonary arteries and also demonstrated a mass near his right kidney along with multiple pulmonary nodules and multiple liver masses. Emergent pulmonary embolectomy was done with nodule biopsy obtained. Ultimately diagnosed with renal medullary carcinoma with metastases.
Discussion: Besides the important lesson of keeping a differential broad, this case has an interesting diagnosis as well. Renal medullary carcinoma is a highly aggressive cancer with an extremely poor prognosis. Neither chemotherapy nor radiation have been shown to be efficacious and the mean survival time is less than 1 year. Metastasis at presentation is extremely common. It almost always affects patients with sickle cell trait and median age is 19 to 22 years old with a male predominance. The most common presenting signs and symptoms are weight loss, hematuria and abdominal or flank pain.
Conclusions: Not all respiratory distress in an asthma patient is an asthma exacerbation. Identify the signs and symptoms of pulmonary embolism and remember not to limit the differential.