Which condition is characterized as being associated with nursing?

Galactocele is a condition that specifically relates to lactation and is characterized by the accumulation of milk in a cyst-like structure in the breast. It typically occurs in women who are breastfeeding, resulting from a blocked milk duct. This condition may present as a palpable, movable lump in the breast that can be clinically or radiographically evaluated.

In contrast, the other conditions listed, while they may affect breast tissue, do not have the same direct association with nursing. Fibroadenoma is a common benign breast tumor occurring predominantly in younger women and is not linked to lactation. Fat necrosis usually occurs in the context of trauma to the breast tissue or previous surgeries, leading to areas of necrotic fatty tissue, rather than being a condition directly related to nursing. Hamartoma is a benign tumor that can occur in various tissues and does not specifically connect to the breastfeeding process. Thus, when considering conditions associated with nursing, galactocele is the condition that accurately fits this context.