11th April 2024

An 18-year-old male presents with acutely tender breast tissue.

An 18-year-old male presents with acutely tender breast tissue. On examination, there is symmetrical, palpable breast tissue extending beyond the area under the nipple bilaterally. He has no significant past medical history and does not take any regular medications. You explain this is gynaecomastia, a benign, physiological change not warranting treatment currently. The proliferation of which structure is responsible for his presentation?

Select the SINGLE most appropriate option from the list below. Select ONE option only.