Tornwaldt cyst is
**Core Concept**
A Tornwaldt cyst is a type of benign salivary gland tumor that arises from the lymphoid tissue of the nasopharynx, specifically from the torus tubarius, a bony projection in the Eustachian tube.
**Why the Correct Answer is Right**
The cyst is thought to be a congenital anomaly that becomes apparent during puberty or adulthood. It is often associated with inflammation or infection of the Eustachian tube, which can lead to symptoms such as nasal regurgitation of food, nasal obstruction, and recurrent infections. The exact mechanism of cyst formation is not fully understood, but it is believed to involve the obstruction of lymphatic drainage from the nasopharynx.
**Why Each Wrong Option is Incorrect**
**Option A:** A Tornwaldt cyst is not a type of salivary gland tumor that arises from the submandibular gland. While it is a type of salivary gland-related lesion, it is specifically associated with the nasopharynx.
**Option B:** A Tornwaldt cyst is not a type of nasopharyngeal carcinoma. While both conditions can affect the nasopharynx, they have distinct clinical and pathological characteristics.
**Option C:** A Tornwaldt cyst is not a type of branchial cleft cyst. While both conditions can arise from embryonic remnants, they are distinct anatomically and clinically.
**Clinical Pearl / High-Yield Fact**
A Tornwaldt cyst is often associated with symptoms that mimic a chronic sinus infection, so it's essential to consider this diagnosis in patients with persistent nasal regurgitation or nasal obstruction.
**Correct Answer: B. A benign tumor arising from the nasopharynx.**