A 17 yo F with no PMHx presents to Urgent Care w/ L sided chest pain. Pain sharp, radiates to L upper back, has been intermittent x 1 month, worse x last 2-3 days. No exacerbating or relieving factors. She denies fever/chills, cough/URI sx, LE pain/edema. No prior hx of DVT, no OCPs. On exam, she is anxious appearing. She is tachycardic to the 120s with normal heart sounds. Spo2 is 100% and breath sounds are diminished on the left. A CXR is done and shown below. What's the diagnosis?(scroll down for answer) 

Answer: Large L sided spontaneous pneumothorax

• Types of pneumothorax:
• Primary PTX: no prior history of lung disease
• Secondary PTX: known lung disease (COPD, asthma, CF, ILD, cancer) 
• Iatrogenic: secondary to invasive procedures (ie: subclavian central line)
• Tension PTX: positive pressure within pleural space
• Differential: PE, pneumonia, pericardidits, pleural effusion, shingles
• Mimics: large emphysematous bullae
• Do NOT insert chest tube
• Obtain CT or perform bedside US to differentiate
• ED treatment
• Tension PTX: CLINICAL diagnosis--> needle decompress --> tube thoracostomy
• Administer O2
• Small PTX (<20%): supplemental O2, 4 hours observation, repeat CXR
• IF improved --> follow up in 24 hours then weekly if resolves
• Aspiration or tube thoracostomy
• Needle aspiration: 14-G (adults) or 18-G (peds) at 2nd intercostal midclavicular space or 4-5th mid axillary
• Chest tube thoracostomy: 10 to 14 Fr if nontraumatic; 14 to 22 Fr if large air leak suspected
• Further management in this case:
• Transferred to hospital
• Placement of 16 Fr thorcostomy by peds surgery at bedside
• Chest tube placed to suction x 48 h then waterseal
• repeat CXR at 4 hours of waterseal revealed no PTX
• Chest tube pulled and follow up CXR at 5 hours post removal was stable--> patient discharged

References: 

Cadogan M. Spontaneous and Iatrogenic Pneumothorax. In: Cydulka RK, Fitch MT, Joing SA, Wang VJ, Cline DM, Ma O. Cydulka R.K., & Fitch M.T., & Joing S.A., & Wang V.J., & Cline D.M., & Ma O(Eds.),Eds. Rita K. Cydulka, et al.eds. Tintinalli's Emergency Medicine Manual, 8e. McGraw-Hill.