Testicular microlithiasis

What it means

Testicular microlithiasis describes tiny, pinpoint deposits of calcium scattered throughout the soft tissue of one or both testicles. Each spot is typically smaller than 3 millimeters — far too small to feel — and on ultrasound they show up as a scatter of bright white dots against the gray background of normal testicular tissue, sometimes described as a "starry sky" pattern. The deposits themselves are made of calcium salts that build up inside the tiny tubules where sperm are produced, and they don't damage the tissue around them.

Why it appears on a CT or MRI report

Microlithiasis is almost always found on scrotal ultrasound, the standard way of imaging the testicles, rather than on CT or MRI. It typically turns up incidentally — while a scan is being done to investigate pain, swelling, a lump, or infertility — rather than because someone was looking for it specifically. The report will describe how many spots are visible and whether they are scattered throughout the testicle (classic microlithiasis) or clustered in one area, and whether one or both testicles are involved.

What it usually means

Microlithiasis is common, showing up in roughly 2 to 5 percent of men who get a scrotal ultrasound for any reason, and in most of those men it is an isolated finding with no other abnormality. On its own, it is not a disease, does not cause pain or fertility problems, and is not itself a tumor. The reason it draws attention is a statistical association: studies have found testicular cancer is somewhat more common in men who also have microlithiasis, particularly with additional risk factors such as a history of an undescended testicle, prior testicular cancer, infertility, or a mass elsewhere in the testicle. Absolute risk in an otherwise healthy man with microlithiasis and no other risk factors remains low, and most men with microlithiasis never develop cancer. Because of this loose association, it is treated as a marker worth watching rather than a diagnosis requiring treatment.

When to follow up

Most guidelines suggest that men with microlithiasis and no other risk factors don't need routine repeat imaging, but should learn how to do a monthly testicular self-exam and see a doctor promptly for any new lump, firmness, or change in size. Men who also have an additional risk factor — a prior undescended testicle, a family or personal history of testicular cancer, infertility, or an atrophic-looking testicle — may be advised to have yearly follow-up ultrasounds, decided together with a urologist. Any new lump, swelling, heaviness, or dull ache in the scrotum should always be checked promptly, whether or not microlithiasis has been noted before.

A plain-language way to picture it

Picture the inside of the testicle as a fine mesh of tiny tubes, and imagine a light dusting of salt settled here and there along that mesh over time. Each grain is inert and doesn't interfere with the tube around it, and none of it forms a lump you could ever feel. On the ultrasound picture, those grains simply reflect sound waves back brightly, which is why they show up as a scatter of white specks. The dusting itself isn't the concern — it's simply a marker that occasionally travels alongside other, separate risks, which is why doctors sometimes suggest keeping half an eye on things rather than ignoring it entirely.