Step 1: Understanding the Question:
The patient is a "16-year-old male" with "recurrent profuse nasal bleeding" and a specific radiological sign: "bowing of the posterior wall of the maxillary sinus".
This constellation of symptoms is the classic "textbook" presentation for JNA.
Step 2: Detailed Explanation:
Juvenile Nasopharyngeal Angiofibroma (JNA):
Demographics: Almost exclusively occurs in adolescent males.
Symptoms: Profuse, recurrent, spontaneous epistaxis and nasal obstruction.
Radiological Hallmark:
Holman-Miller Sign: Anterior bowing of the posterior wall of the maxillary sinus seen on CT or lateral X-ray. It occurs because the tumor originates in the pterygopalatine fossa and pushes the sinus wall forward as it grows.
Analyzing other options:
Antrochoanal Polyp (B): Common in children but causes obstruction, not profuse bleeding. CT shows the polyp coming from the maxillary antrum, but no bone bowing.
Rhinosporidiosis (C): Presents as a friable, "strawberry-like" mass with white dots; usually associated with bathing in stagnant water.
Step 3: Final Answer:
The clinical profile of an adolescent male with severe epistaxis and the Holman-Miller sign on CT confirms the diagnosis of JNA.