Ho-ho-ho! Gather ’round, my curious elves, for I have a tale that’s as rare and unexpected as a reindeer with a shiny red nose. In the bustling workshop of medicine, there was a case that jingled all the way to the attention of the doctors. A 39-year-old patient, who had been prancing through life with relapsing-remitting multiple sclerosis, received a gift not so merry—a treatment with the anti-CD52 potion known as alemtuzumab, a concoction that sends those pesky lymphoid cells on a long winter’s nap.

But, oh, what a twist in the tale! Forty-five months after this patient started on alemtuzumab, a storm brewed, not of snow, but of immune-mediated thrombotic thrombocytopenic purpura (iTTP), as rare as a silent night when the toys are being made. iTTP, my dear friends, is like the Grinch that stole platelets, causing a ruckus in the bloodstream and threatening to dampen the holiday spirit with its life-threatening mischief.

Not to worry, for the medical sleigh was swift! The patient was whisked away for a treatment as magical as Christmas itself—plasma exchange, corticosteroids, and a sprinkle of caplacizumab. And would you believe it? Just like the joy of Christmas morning, clinical remission was achieved in three months, with platelets aplenty and ADAMTS-13 activity as restored as the twinkle in my eye.

So, let this be a lesson, my jolly assistants: if ever you encounter a patient with signs of thrombotic microangiopathy after a dance with alemtuzumab, think of iTTP. It may be as rare as a toy workshop at the North Pole, but it’s real, and with a dash of holiday cheer and medical know-how, it can be overcome. Now, back to toy-making, and let’s keep those spirits bright!