Morvan's syndrome: An unusual presentation of a solid pseudopapillary pancreatic tumor.

Morvan's syndrome is a rare anti-contactin-associated protein-like 2 (CASPR2) antibody-mediated autoimmune disorder. The clinical features of this syndrome include muscular twitching, insomnia, dysautonomia, peripheral nerve hyperexcitability, and fluctuating delirium. An underlying tumor is commonly found among Morvan's syndrome cases, with thymoma being the most frequent association. We describe an unusual case of a 39-year-old female with excruciating bilateral leg pain, insomnia, hyperhidrosis, peripheral nerve hyperexcitability, serum anti-CASPR2 antibody positivity, and a solid pseudopapillary tumor of the pancreas on histopathology. Furthermore, the patient's symptoms improved after receiving intravenous immunoglobulin (0.4 g/kg per day for 5 days). To the best of our knowledge, this is the first case of Morvan syndrome associated with a solid pseudopapillary pancreatic tumor to be reported in the literature to date. Our case adds to the spectrum of malignancies that are associated with Morvan's syndrome. The recognition of this rare syndrome and its various associations are important for the neurologist, as it is a potentially treatable condition.