<s>[INST] Hi, I have a lump under my right nipple and I'm a boy 12 years old. It is abt 3 cm big and has lasted for a month. It's gotten bigger over time I'll say tripled. It's painless except for when pressure is applied. Its pretty far from the surface and I've been slowing down alot, and having nausea. [/INST] hi.it is best if you consult with a doctor, preferably a general or a pediatric surgeon, for medical and physical examination. based from your description, it could be a cyst. even if you're a boy, breast lesions could also occur. it could also be a fibroma or fibrocystic lesion. these lesions are best evaluated clinically. further diagnostic examinations, such as breast ultrasound, will be requested as needed. management (medical and/or surgical) will be directed accordingly.hope this helps.good day!!~dr.kaye </s>