I have a lipoma and had thyroid cancer. my seven year old has two lipomas. are they truly benign or can this be a sign of an underlying disorder?

Familial lipomas?: You might want to read this: http://www.Cancer.Net/cancer-types/cowden-syndrome. As you can see, there are certain familial conditions that feature lipomas and thyroid neoplasms. From the information you provided, i cannot tell whether or not you might have this or some other syndrome, but the clustering of tumors suggests there might well be a familial syndrome at play.

Not related: Lipomas are benign fatty tumors that are totally unrelated to thyroid cancer. Lipomas do tend to run in families, but are still benign in that situation.

No relation: Lipomas are benign growths developing in adipose tissue. They are not related to any malignancies but can on their own, progress to develop malignant transformation. If lipoma begins to grow rapidly and noted to become firm in consistency rather than softi , then bx is indicated. The majority of lipomas do not convert and have not been reported to be involved in any tumor syndrome