Managing Incidental Findings: A GP's Guide to Incidentalomas

Modern scanners see almost everything, and much of what they see was never the question. Incidental findings - "incidentalomas" - are unexpected abnormalities detected on a study performed for an unrelated reason, and they are common: scan enough abdomens and chests and a substantial proportion will contain a nodule, cyst or lesion of some description.

The overwhelming majority are benign. The clinical challenge is that a small minority are not, and distinguishing the two after the fact consumes consultations, follow-up imaging, procedures and patient peace of mind.

For the GP, incidentalomas arrive in two ways: in reports of scans you ordered, and in reports from hospital or specialist imaging that land in your inbox with the follow-up implicitly delegated to you. Both require the same discipline - a structured response, clear communication, and documentation that survives the years over which surveillance sometimes runs. The best prevention, of course, is not ordering low-value scans in the first place.

Incidental thyroid nodules turn up frequently on neck ultrasound, carotid Doppler, CT of the chest or neck, and PET. The background reality is reassuring: thyroid nodules are extremely common in the general population, the large majority are benign, and even many small malignant nodules behave indolently.

The general framework: not every incidental nodule needs workup. Guidelines (including widely used sonographic risk-stratification systems such as TI-RADS) direct fine-needle aspiration and follow-up based on the nodule's size and its ultrasound features - composition, echogenicity, margins, calcifications - rather than its mere existence. Small nodules with benign sonographic features generally need no further action; larger nodules or those with suspicious features warrant dedicated thyroid ultrasound and possibly biopsy.

A nodule found on CT or PET usually needs a dedicated ultrasound to characterise it before any decision. Check TSH before considering biopsy - a hyperfunctioning nodule follows a different pathway. Follow the radiologist's specific recommendation, and consult current endocrine guidance where the report is silent.

Adrenal incidentalomas appear on a meaningful fraction of abdominal CTs, and the two questions are always the same: is it hormonally active, and could it be malignant?

Most incidental adrenal lesions are benign, non-functioning adenomas, and imaging characteristics do much of the sorting - small size and low attenuation on unenhanced CT (reflecting lipid content) are reassuring features the radiologist will usually comment on explicitly.

The piece that falls to the referrer, and is most often missed, is the biochemical workup: current endocrine guidance recommends assessing incidental adrenal lesions for autonomous cortisol secretion, and for phaeochromocytoma in lesions without clearly benign imaging features, with aldosterone assessment in hypertensive or hypokalaemic patients. Lesions that are large, growing, or indeterminate on imaging warrant specialist referral.

Practical habit: when an adrenal incidentaloma appears in a report, treat "benign-appearing" as an imaging statement only - it does not answer the hormonal question, which requires blood and urine tests you initiate.

Incidental pulmonary nodules are among the most anxiety-provoking findings for patients, because everyone hears "spot on the lung" the same way. The evidence base, however, is well developed: management is guided by structured frameworks (the Fleischner Society recommendations being the most widely referenced) that stratify follow-up by nodule size, solidity (solid versus subsolid), and the patient's risk profile - principally smoking history and age.

In general terms: very small solid nodules in low-risk patients often require no follow-up at all; intermediate nodules earn surveillance CT at defined intervals; larger or suspicious nodules proceed to PET-CT, respiratory referral or biopsy. Subsolid nodules follow longer surveillance timelines. Australian radiologists usually cite the applicable recommendation directly in the report.

The GP's critical contribution is the risk context the radiologist may not have - an accurate smoking history, prior malignancy, occupational exposures - and the follow-through: a surveillance CT recommended for twelve months' time only happens if a system, not memory, ensures it is booked.

Simple renal cysts are so common with age that they barely qualify as findings - a well-defined, thin-walled, fluid-density cyst described as simple requires no follow-up, and patients can be told so plainly. Complexity changes the picture: septations, calcification, thickened walls or enhancement move a cyst up the classification (radiologists use the Bosniak system), with higher categories warranting dedicated imaging or urological referral. The report will normally state the category and the recommendation.

Beyond the classic four, incidentalomas have a long tail - hepatic lesions, ovarian cysts, thyroid uptake on PET, bone islands, meningiomas. Two general rules serve well. First, follow the radiologist's explicit recommendation, which usually reflects current consensus frameworks; where a report describes a finding but offers no guidance, phone the radiologist - a two-minute conversation beats guesswork. Second, resist symmetrical anxiety: findings explicitly characterised as benign do not need surveillance "just in case", and over-following benign findings is its own harm.

The conversation matters as much as the pathway. Patients hear "they found something" as "they found cancer" unless you actively frame it otherwise:

• Lead with the base rate - "Scans pick up small findings in a large share of people, and the vast majority turn out to be nothing of consequence" • Name the plan, not just the finding - "a repeat scan in twelve months" is a plan; an unexplained finding is a threat • Be honest about the residual uncertainty - most patients tolerate "very likely benign, and we're checking to be sure" far better than false certainty in either direction • Explain why waiting is safe when surveillance intervals feel long - the interval itself encodes how low-risk the finding is • Invite the questions - fear that goes unspoken in the room gets processed at 2 am instead

Incidentalomas are a well-recognised medico-legal fault line, and the failure mode is nearly always the same: a surveillance recommendation noted, agreed, and then lost. Habits that prevent it:

• Record the finding, the recommendation and its source (report date, framework cited) in the problem list or an equivalent visible place - not only in the buried document • Enter the follow-up as a concrete recall in your practice software at the point of reading the report, not later • Document the patient conversation - what was explained, what was agreed, and an informed decision to decline surveillance if the patient makes one • On any subsequent imaging referral, mention the finding under surveillance so comparison happens • When care transfers, make the surveillance item explicit in the handover

A finding tracked properly is a minor administrative task; a finding lost is the malignancy diagnosed two years late. This article is general professional information - the specific surveillance frameworks evolve, so consult current guidance and your reporting radiologist for individual cases.