Paraneoplastic Stiff Person Syndrome With Anti-amphiphysin Antibodies Presenting With Pruritus as the Initial Manifestation: An Unusual Case

Stiff person syndrome (SPS), also known as Stiff-man syndrome/Moersch-Woltman syndrome, is a rare disorder of the central nervous system, first described in 1956, characterized by rigidity and stimulus-triggered painful muscle spasms of predominantly axial and proximal limb muscles. There are many variants of SPS; these include the classical SPS, stiff leg syndrome, and paraneoplastic variant. The paraneoplastic variant of SPS is more common in patients with breast cancer with anti-amphiphysin antibodies, followed by colon carcinoma, lung carcinomas, thymoma, and Hodgkin's lymphoma. A possible autoimmune origin for the disease has been proposed, including antibodies against glutamic acid decarboxylase and amphiphysin. We thus describe a case of anti-amphiphysin antibody-positive SPS, which initially manifested with generalized pruritus. After extensive investigations and removing her underlying tumor, she reported complete recovery of her symptoms.