18-year-old woman • chest pain • shortness of breath • electrocardiogram abnormality • Dx?

Radiographic imaging is essential to elucidate the diagnosis. Chest radiograph can show an intrathoracic mass, and CT can provide further characterization, such as density and precise location.

Location of mass guides differential

Localizing an intrathoracic mass in the anterior, middle, or posterior mediastinum allows for narrowing of the differential diagnosis (TABLE⁶). The main diagnostic consideration for a middle mediastinal or hilar mass is primary carcinoma. Posterior mediastinal masses, on the other hand, are generally of benign etiology and may include neurogenic tumors, foregut duplication cysts, or, in rare cases, extramedullary hematopoiesis.

The differential diagnosis of anterior mediastinal masses can be separated into 4 main categories of disease, colloquially known as the “4 Ts”:

Teratoma. Mixed tissue densities seen on CT relate to the multiple tissue types originating from the embryologic germ cell layers.Frequently, there will be fat, fluid, and calcifications.

Thyroid pathology. A goiter or thyroid cancer can manifest with endocrine dysfunction, such as thyroid-stimulating hormone and T3/T4 abnormalities. A thyroid mass tends to sit more superiorly than do other anterior mediastinal masses and may be confirmed using a nuclear scan looking for increased radioactive iodine uptake.

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