Patient presents with complaints consistent with pneumomediastinum, including sudden onset of chest pain, often described as sharp or tearing, and potentially radiating to the neck, back, or shoulders.  Subcutaneous emphysema, noted as a crackling sensation upon palpation of the neck or chest, may be present.  The patient may also exhibit Hamman's sign, a crunching or clicking sound synchronous with the heartbeat, auscultated over the precordium.  Dyspnea and dysphagia are also possible presenting symptoms.  Differential diagnosis includes esophageal rupture, pneumothorax, and myocardial infarction.  Chest radiography, often the initial imaging modality, may reveal characteristic findings such as the ring sign or continuous diaphragm sign, indicative of air dissecting along mediastinal structures.  CT scan of the chest provides greater sensitivity and specificity for confirming the diagnosis of pneumomediastinum and evaluating the extent of air within the mediastinum.  Etiology may be spontaneous, secondary to forceful Valsalva maneuvers, or related to underlying medical conditions such as asthma, COPD, or iatrogenic causes like endoscopic procedures.  Management of pneumomediastinum typically focuses on treating the underlying cause and providing supportive care, including analgesia for pain management and supplemental oxygen as needed.  Surgical intervention is rarely required, reserved for cases with significant complications such as airway compromise or suspected esophageal rupture.  Patient education regarding avoidance of activities that increase intrathoracic pressure is essential.  Follow-up chest imaging may be indicated to monitor resolution of the pneumomediastinum.  ICD-10 code J98.8, other specified diseases of the mediastinum, is appropriate for primary spontaneous pneumomediastinum, while alternative codes may be necessary depending on the underlying etiology, requiring careful medical coding for accurate billing and reimbursement.