This may turn out to be an excellent case Chandra.

The reason why I say so- is because I encountered a similar case 3 years ago, and the memory of it is still refreshing because it required a lot of 'head scratching' to figure out what was wrong- but ultimately I was able to find out (in that case) the problem - a lucky shot- but it earned me the 'Dr. House' title from my colleagues. :-)

Before I narrate that case- let me ask you a few other questions- 1) Was the increase in appetite significant? 2) How many years since she rapidly gained weight? (as evidenced from her growth chart) , 3) Any documented hypotension/shock at any time?, 4) Any unexplained 3rd space fluid collections?, 4) Sleep rhythm?, 5) Any significant infection prior to the start of these changes requiring hospitalizations? 6) Any history of trauma?

7) What all imaging studies of what all body parts were done? 8) Investigations on blood/ urine? 9)What about the weight /history in family members? 10) Developmental history? 11) Was ABG/ sugar monitoring done?

OK- now coming to the case

I had a patient - an 8 year old girl who was referred as a case of septic shock. She was obese, and her parents had tols us that till the age of 6 she was growing normally, then had an episode of fever(lasting 6 days), and since then she had been eating voraciously and gained weight rapidly. He parents were of medium build.

The child was hypoxic and in shock on admission, and required venous cut-down. She was ventilated in view of severe respiratory distress, which was caused by massive pleural effusions bilaterally. She was intubated and ventilated with a reatively high PIP/PEEP, and the following bedside USG thorax confirmed the findings. Cardiac echo showed diastolic dysfunction. ABG showed respiratory acidosis. Renal functions, and blood workup was normal. Dengue serology was negative, septic screen was negative, serum proteins were borderline.

We initially thought of the effusions and the progressive weight gain/polyphagia as two separate entities, but by day two had to consider the possibility that they could be related.

By evening of day 2, child's condition improved, as we could lower her ventilator settings. On day 3 morning, she self-extubated, and was surprisingly stable. She was interacting with her parents as well A repeat USG thorax showed almost 80% reduction in her pleural effusion- which perplexed me to no end. We did an MRI brain- which was normal.

By this time we were considering almost everything- right from Diabetes to Kleine Levin, Bardet- Biedl, an amygdaloid dysfunction etc. Hypothyroidism was ruled out. USG KUB was normal. So was Serum cortisol.

On day 4 noon- child again had a rapid decompensation, and had to be ventilated again, although this time, a CxR did not show any effusion. We gave her IV fluid boluses and then hemodynamics stabilized, by day 5 she again self extubated- but continued to be stable thereafter.

At this point I suggested a thoracic MRI - especially of the thorax because the rapid disappearance of the effusions was still most puzzling. I added a 'malignancy- ? lymphoma' also into my probable diagnosis sheet.

we shifted the patient via ambulance to a super specialty centre, and got the MRI done- and lo!- there was a mediastinal lymphoma. A screening of other areas was normal.

She was subsequently operated after 2 months, and is now on chemo. Her weight has started dropping (probably multifactorial causation).

So In short- keep an open mind, and the more puzzling a patient- work even more towards the diagnosis.Wish you success!