12 month MRI says "increased in size compared with prior". First scan was FINE. How is bigger ever not the bad news?

Acoustic neuroma, treated last June. Some of you saw me in the "stable, no change" thread being nervous about my first scan, which came back fine at six months. I actually let myself relax after that one.

Twelve month scan was last week. Report landed in the portal this morning: "the lesion measures 16 x 14 mm, previously 14 x 12 mm, increased in size compared with prior studies." The nurse rang before I'd even finished reading it and said the team had reviewed it, they are "not concerned", it is "likely treatment effect", rescan in six months.

Not concerned. It is two millimetres bigger in every direction. The whole POINT of the treatment was to stop it growing, and at one year it has grown, and everyone is being calm at me. I went out and walked eleven miles today and it did not help.

So please, from people further down the road: has anyone actually had one get bigger and then smaller? And how do they KNOW it's swelling and not the tumour just carrying on? Because from where I'm sitting "likely" is doing a lot of work in that sentence.

Pete, I'm the resident got-bigger-then-smaller exhibit, so let me flesh out the story I've told here before, because the details are what helped me.

My first meningioma scan said "marginally increased" and I spiralled for a fortnight until I asked the registrar to actually show me the pictures rather than the sentence. Two things on that screen changed everything. First, the middle of the tumour had gone dark on the contrast scan, and she said that darkening IS the treatment working, the centre losing its blood supply, and that tumours which are dying often puff up before they shrink. Second, she pointed out that my "increase" was about the width of the line they draw to measure it. Different scanner that day, slightly different slice angle, and a millimetre or two appears out of nowhere.

Mine kept looking swollen through about month nine, was flat by eighteen months, and measured smaller at two years. Nobody at the clinic was surprised at any stage except me.

AVM here, so a different lesion but the same lesson turned up to eleven: my scans are practically REQUIRED to look worse before they look better. There's a bright halo around mine on some sequences that my team greeted like an old friend, expected reaction, right on schedule. Reading the site's piece on radiation necrosis, calmly explained when that halo first appeared is what finally got it through to me that the picture getting uglier and the treatment failing are two different things.

Following this one nervously, my own twelve month scan is booked for the end of July and I had quietly assumed that after a stable six month result the only remaining direction was down.

Question for the room while we have it: is there a point where they stop saying swelling and start saying growth? Because "likely treatment effect, rescan in six months" sounds reassuring right up until you ask what happens if the next one is bigger too.

Pete, what your team is describing has a name, and I find patients do better with the name than with "likely": pseudoprogression, usually called transient expansion in the acoustic neuroma literature. A proportion of these tumours swell temporarily after radiosurgery before they settle, in published series somewhere between roughly one in ten and one in three depending on how enlargement is defined. It most often appears between about 3 and 18 months, which is exactly where you are, and it settles over the following one to two years. The mechanism is the treatment itself: the dose injures the tumour's internal blood supply, the tissue reacts and swells, and the target looks larger while it is in fact being switched off.

How radiologists tell the difference is a pattern, never a single number. Paul's registrar showed him the most reliable sign: loss of enhancement in the centre of the target, the middle going dark on contrast, which reflects treatment effect rather than growth. They also weigh the trend across your whole sequence rather than one comparison, they increasingly measure volume rather than a single diameter, and they treat a 2 mm change with appropriate suspicion, because slice positioning and scanner differences alone can produce it. To Mark's question, what shifts the conversation from swelling to growth is persistence: continued, sustained enlargement across successive scans beyond the two to three year window, or a target that regains solid enhancement while it grows. That is also why nobody makes a re-treatment decision on one image, and why the answer to enlargement at twelve months is a scan at eighteen, not an intervention. If swelling causes symptoms in the meantime, a short course of corticosteroids manages it; silent swelling like yours is usually just watched. The site's guide to results and follow-up after Gamma Knife covers the expected shape of these curves condition by condition.

What I cannot do from here is read your images, and the pattern is precisely what matters. Ask your team to walk you through the pictures side by side, the centre of the target especially. Most centres will do this gladly, and patients who have seen the darkening with their own eyes tend to sleep better than patients holding a sentence.

Update, because I hate threads that leave you hanging.

Got an appointment and asked for exactly that walk-through. The consultant put the two scans up side by side and there it was, the middle of the thing noticeably darker than a year ago. He used the words "textbook transient expansion", agreed the measurements have a wobble in them, and showed me the volume numbers, which have barely moved. Rescan in December.

I won't pretend I'm serene, but I'm sleeping, and "the middle going dark" has joined "boring is the goal" on the list of phrases doing heavy lifting in this house. Thank you all, genuinely.