You are seeing a 45-year-old female in a primary care setting who has presented with some lumps under her armpits that she is concerned about. On questioning, the patient informs you that these lesions appeared several weeks ago and are not painful she just wants to get them checked out. On examination, you note the presence of dome-shaped, flesh-coloured papules with a central umbilication. They are around 4mm in diameter. What is the most likely diagnosis?