Why Would a Female Have a Hard Lump under Her Belly Button?

There are several potential causes for a hard lump under the belly button. One common cause is an umbilical hernia, which occurs when tissue like fat or part of the intestine pushes through a weak spot in the abdominal wall at the umbilicus. Sometimes these hernias feel firm, especially if the tissue becomes trapped or fibrotic. Another possibility is an epidermal inclusion cyst, a benign lump that forms when skin cells accumulate beneath the skin. In females, umbilical endometriosis is also a consideration. This happens when endometrial tissue, which normally lines the uterus, implants in or around the belly button, often leading to a firm, sometimes painful nodule that may fluctuate with the menstrual cycle. Although much less common, a hard umbilical nodule might also represent a Sister Mary Joseph nodule, which is a sign of metastatic cancer from internal organs such as the gastrointestinal tract or reproductive system. Because these conditions vary greatly in terms of severity and treatment, it is important to have any new or persistent lump evaluated by a healthcare provider. They may use imaging tests or a biopsy to make an accurate diagnosis and determine the best course of action.