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Screenings by age and gender

Spleen lesion found by chance: follow-up scans

A spleen spot, or focal splenic lesion, is sometimes seen on a CT, MRI or ultrasound done for another reason. The vast majority are benign. (Teja 2026) This page covers which spots need more scans, which kind and how often, not biopsy, surgery or treatment.

The main guidance

  • ACR 2013 white paper (American College of Radiology): spleen and lymph node findings found by chance on CT and MRI, with flowcharts. (ACR 2013)
  • CAR 2026 (Canadian Association of Radiologists): spleen and node findings in adults, building on the ACR guidance with newer evidence and aiming to cut unneeded follow-up. (CAR 2026)
  • WFUMB 2021 (World Federation for Ultrasound in Medicine and Biology): spleen findings found by chance on ultrasound, and which need no further tests, a repeat scan or prompt tests. (WFUMB 2021)

The full texts of these three are behind a paywall. The details below come from open-access reviews that summarise them, and name the guideline each point comes from. (Corvino 2023)(Teja 2026) Corvino 2023 notes that none of the published approaches has yet been tested in prospective studies. (Corvino 2023)

Your history comes first

Reviews say the first step is to sort people by whether they have a history of a solid cancer or a blood cancer such as lymphoma, and to check for symptoms such as pain in the upper left belly, fever or weight loss. (Corvino 2023) In Siewert 2018, spleen spots found by chance were cancer in 1.0% of people with no cancer history or symptoms, compared with about a third of those with a known cancer. (Siewert 2018)

Findings that usually need no follow-up

  • Benign-looking spot, such as a simple cyst: fluid-filled or even, with smooth edges and no contrast uptake, needs no further tests or follow-up. (Corvino 2023) WFUMB 2021 lists no further assessment for spots with no echoes on ultrasound, and says many findings, such as spare spleens (splenules) and spleen cysts, need no further tests. (Corvino 2023)(WFUMB 2021)
  • Spot stable on older scans: ACR 2013 says a spot that has not changed for more than a year needs no follow-up. (Corvino 2023)
  • Scattered small calcium specks with no mass need no further work-up. (Corvino 2023)
  • Unclear spot with no cancer history and no symptoms: CAR 2026 says even a spot that stays unclear on CT or MRI does not need dedicated follow-up imaging. (Teja 2026)

When a repeat scan or MRI is usual

Follow-up for a spleen spot that is not clearly benign (simplified)
GuidanceWhoWhat and how often
ACR 2013No cancer history, unclear look, no older scansMRI at 6 and 12 months
ACR 2013Cancer history, spot under 1 cmMRI at 6 and 12 months
ACR 2013Cancer history and spot 1 cm or more, or no cancer history but suspicious lookFurther tests (PET, MRI or biopsy)
WFUMB 2021Bright (echo-rich) spot on ultrasoundRepeat ultrasound at 3 months
CAR 2026No known cancer, no symptomsNo dedicated follow-up imaging, even if unclear

Sources for the table: the ACR 2013 and WFUMB 2021 rows from the Corvino 2023 summary, the CAR 2026 row from the Teja 2026 review. (Corvino 2023)(Teja 2026) Corvino 2023 also summarises a review by Thut and colleagues: in people with no symptoms, MRI for complex cysts and solid spots, no follow-up if MRI shows a haemangioma or a cyst with old bleeding, and follow-up imaging in 6 to 12 months if MRI stays unclear. (Corvino 2023)

What changes the plan

  • Growth or change in size on a later or earlier scan means further tests. (Corvino 2023)
  • A history of cancer, especially with a spot of 1 cm or more. (Corvino 2023)
  • Features that look less benign, such as blurred edges, low blood flow on contrast scans or solid parts that take up contrast. (Corvino 2023)
  • Symptoms such as fever, weight loss or pain in the upper left belly. (Corvino 2023)(Siewert 2018)

Routine age-based screening

A spleen spot found by chance does not replace the routine screenings for your age. For other findings on a scan, see liver lesion found by chance, pancreatic cyst found by chance, kidney cyst found by chance and adrenal mass found by chance.

Where they differ:

  • Unclear spot in a person with no cancer history. ACR 2013 lists MRI at 6 and 12 months; CAR 2026 says no dedicated follow-up imaging is needed when there are also no symptoms. (Corvino 2023)(Teja 2026)
  • Which scan. ACR 2013 covers CT and MRI and did not consider ultrasound; WFUMB 2021 builds its plan on ultrasound and contrast ultrasound. (Corvino 2023)
  • How soon. WFUMB 2021 lists a repeat ultrasound at 3 months for an echo-rich spot; ACR 2013 lists MRI at 6 and 12 months. (Corvino 2023)

Your doctor decides what your result means for you.

Questions people ask

Are most spleen spots found by chance cancer?

No. In Siewert 2018, 2 of 205 people (1.0%) whose spleen spot was found by chance had cancer, and in both a tumour elsewhere already showed it. The authors concluded follow-up may not be needed. (Siewert 2018)

Does a simple spleen cyst need follow-up?

Usually not. A spot that looks clearly benign, such as a smooth, even, fluid-filled spot with no contrast uptake, needs no further tests or follow-up. (Corvino 2023) (WFUMB 2021)

My spot was on an older scan too. Does it need more tests?

If it has stayed the same size for more than a year, ACR 2013 says no follow-up is needed. If it has changed size, it needs further tests. (Corvino 2023)

Why might a past cancer change the plan?

Guidance sorts people by cancer history first. With a past cancer, a spot of 1 cm or more that is not clearly benign is checked further rather than watched. (Corvino 2023) (Teja 2026)

Can a haemangioma look bigger on a later scan?

Yes. Corvino 2023 notes that a haemangioma can look slightly larger or smaller on a later scan because of the timing of the contrast, and that this should not be read as true growth. (Corvino 2023)

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