Docetaxel-induced nail changes--a neurogenic mechanism: a case report.

Docetaxel is a new taxoid widely used in chemotherapy for advanced breast cancer and other solid malignancies. Painful nail changes with onycholysis occur in about 40% of docetaxel-treated patients as a prominent adverse effect. We report a patient with a complete peripheral palsy of the right arm due to advanced breast cancer with diffuse tumor infiltration of the brachial plexus. Treatment with docetaxel led to onycholysis at all extremities except the paretic hand. Sensory and motoric innervation measured by nerve conduction studies showed a complete loss of large nerve fiber function of the right arm. Function of deep mechanosensitive A beta-fibers (quantitative vibrametry) was severely decreased, but not absent. Sympathetic reflexes (induced by deep inspiration and measured with laser Doppler flowmetry) were absent on the right side and skin temperature was decreased consistent with a complete sympathetic denervation. Small afferent fibers investigated by quantitative thermotesting revealed a total loss of thermal and pain sensation. Furthermore, iontophoresis of histamine failed to induce any axon reflex-vasodilatation indicating a complete peripheral degeneration of small fiber afferents. In summary, a severe denervation of small and large fibers of the right upper limb was revealed. These results indicate that integrity of peripheral nerves seems to be a substantial factor for docetaxel-mediated nail changes. The role of an inflammatory process in onycholysis maintained by postganglionic sympathetic terminals and nociceptive C-fiber afferents is discussed. In accordance with this hypothesis, a cyclooxygenase-2 inhibitor improved nail alterations of the non-paretic limbs.