Introduction: A 64-year-old woman presented with symptoms of subacute exacerbation of a year-long carpal tunnel syndrome that was caused by a large calcified mass in the tunnel.
Conclusion: The resected mass consisted of very tiny rods, and x-ray diffraction analysis, as well as the component analysis using energy dispersive x-ray microanalysis, revealed the mass to be most compatible with apatite. The back-scattered electron images suggested that precipitation might be a mechanism for development of the calcified mass.