Cracking the calcium code: Diagnosing hydroxyapatite deposition disease

Acute calcific periarthritis (ACP) of the great toe is a very rare presentation of hydroxyapatite deposition disease (HADD) in an unusual site, often causing acute pain, swelling, and reduced motion of the affected joint which may mimic trauma or infection. Diagnosis can be challenging, which often requires radiological imaging and the treatment is primarily conservative. In this case report, we wish to highlight the features of this rare entity in an unexpected site, that is, ACP of foot in a young female who presented with acute onset pain in the right great toe.