Congenital insensitivity to pain with anhydrosis. Report of two unrelated cases.

Two unrelated female cases of congenital insensitivity to pain with anhydrosis are presented. The first case was born from consanguineous parents. In both cases, onset of manifestation was observed in infancy with automutilation and recurrent fever. Both were mentally retarded. They underwent a peripheral nerve biopsy respectively at 3 and 33 years. A dramatic loss of unmyelinated fibers was observed in both cases. Myelinated fibers were also moderately reduced in number, especially those of smallest diameter; this loss was more marked in the second patient who was adult when the peripheral nerve was studied. Clusters of regenerating myelinated fibers were seen in both cases. Such histological observations might suggest a slowly progressive disorder. The cases are discussed together with previous reports dealing with congenital insensitivity to pain.