Patients-not just Images

Devoted to Education and Practice in Patient-centered Radiology

Digging deeper into Pica

Sameer Kalgaonkar, Ravi Ramakantan

This is an example of how staring at the surface gets you nowhere – if you want to hit gold, you have to keep digging deeper. This may mean some hard work and not a little bit of wanting to know the answers to the questions that you had never asked - till now.

A five-year-old boy presented to the paediatrics department of our hospital with crampy abdominal pain since many days. The mother also said that the child had been constipated for several months and needed laxatives often and on.

An upright film of the abdomen was done. (image below). That showed no abnormal air fluid levels. However, strange well-defined, irregular, approximately 5 mm to 10 mm radiopaque shadows were seen throughout the abdomen – especially along the course of the large bowel.

Even as we raked our brains as to what these radiopaque shadows could be, our department's tag-line kept coming back to our mind. We do agree with Benjamin Felson when he says that the 'world's greatest consultant to a radiologist is the patient's previous radiological investigations' (there were none for this patient) ; we go one step ahead and say and we believe that Radiology is about Patients and not just Images. It was therefore natural for us to turn to the patient's mother and ask a detailed history. Whereupon, she said that the child has been asking for an unusually large number of erasers over the past several months. We then wondered if the shadows that were seen in the abdomen could be those of the erasers that the child might be eating as a part of a disease process which is familiar to all of us by the name of Pica - in which, the patient eats non-nutritive substances at the age where such behaviour is not appropriate. This often involves scratching the paint on the wall and eating them (leading to lead toxicity) or sometimes eating dirt or even faeces. But, we have not often heard of Pica being produced by 'addiction' to rubber erasers.

Before looking any further, we wondered: Pica?.

Why call something 'Pica'?



It turns out that the word Pica in Latin means the bird Magpie. This bird is to reputed to eat whatever comes its way. And, look very closely and you'll see that it has an uncanny resemblance to our common crow which pretty much eats everything up.

And so, we could have said that based on the history that the mother gave, that the child suffered from Pica due to eating of rubber erasers and we could have been deeply satisfied that we had made the correct diagnosis and lived happily ever after!

But, that would've always left an unanswered question in our mind as to "why is the rubber in the eraser really so radiopaque?"

To understand this, we got a bunch of these erasers from a stationary shop and cut them up into small pieces like those seen on the film of the abdomen(images below).

We then obtained a radiograph of the pieces of rubber fancifully arranged in the pattern of the letter R – representing Research in Radiology. The rubber pieces were very radioopaque.

We also obtained a CT scan of a single piece of the rubber and where quite taken aback to see that the density of this piece of rubber measured about 850 Hounsfield units. This is very dense indeed .(Image below).

But, we wanted to know what is it in the rubber that makes it so radioopaque.

A little bit of research on Google told us that the following are the constituents of the commonly used a rubber eraser.

Styrene-butadiene rubber


Colour pigments

Vegetable oil

It is obvious that the sulphur which is used for vulcanisation of the rubber was indeed the one responsible for producing the radio opacity. But, fortunately, in the eraser, the sulphur is in the compound form and it does not get absorbed from the GI tract and produces no harm to the patient systemically.

Pica is considered to be a psychological disease and this boy is now under the treatment of a child psychologist for the same. Hopefully, in a few weeks we'll be able to show you a repeat film of the abdomen and report on how the child is doing in terms of eating of erasers.

What I wish to stress is this:

As radiologists, we had two options: The one that we would normally have followed was to report "Multiple radiopaque foreign bodies seen in the abdomen .. no free air.. no fluid levels" etc. And end with "Suggest clinical correlation". Honestly, this is what most would have done.

But, here we were curious to dig deeper and that threw up an altogether new ballgame and we learned a lot about the patient, materially contributed to clinical care and also did a bit of 'basic research' on radiopacity of rubber.

In all this, the radiology residents who work with us saw a new face of the practice of radiology in everyday's work and we believe, it counts for a lot.

I firmly believe that talking to patients-as and when required .. as and when presented with a puzzling case, is an integral part of everyday practice of radiology. I have seen it helps immensely in 'radiology care'.

And to me, the "Where is time?" excuse does not wash.