Case Presentation: A 75-year-old female with a past medical history of hypertension and hyperlipidemia presented with one month history of worsening gait instability, imbalance, and intermittent visual disturbances. Neurological examination showed absent vibration sensation in both feet, brisk reflexes with bilateral upgoing toes, and marked gait instability. An outpatient lumbar spine MRI was normal. CT head demonstrated chronic small-vessel ischemic changes and brain MRI showed symmetric periventricular and pericallosal white-matter changes consistent with age but insufficient to explain her rapid decline. CSF analysis showed signs of an inflammatory process. CT abdomen and pelvis revealed a 7.5-cm left hemi pelvic mass concerning for an ovarian malignancy. Surgical resection confirmed a stage IIIC high-grade serous carcinoma involving the left ovary and fallopian tube with metastases to the rectum, omentum, and cervical tissues. Immunohistochemistry demonstrated PAX8 positivity with p53-null expression. An antibody panel returned positive for anti-Yo antibodies, establishing the diagnosis of paraneoplastic syndrome secondary to ovarian carcinoma. The patient received high-dose steroids and five sessions of plasmapheresis without neurological improvement. Given her progressive decline and poor prognosis, she elected hospice care.
Discussion: Anti-Yo–associated PCD is a rare but aggressive paraneoplastic syndrome primarily linked to gynecologic and breast cancers, with ovarian cancer in this case. Neurological symptoms often appear first, but the imaging and testing we do initially may not correlate with the acuity or severity of the symptoms which can delay treatment. Oftentimes, it is when we have ruled out all the other common causes of ataxia do we need to consider PCD, particularly in women with no reported breast or gynecologic cancer in either the past medical history or the initial workup. Once the anti-Yo titers are positive, we as providers need to find the source of the cancer because it is the cancer releasing the antibodies and causing ataxia. By finding the source we can control and even reverse some of the symptoms. However, the neurological deficiencies may be too great. As clinicians, we need to be proactive when all other avenues of ataxia have been ruled out and consider the possibility of PCD despite its rarity and do the appropriate testing for it.
Conclusions: While ataxia is associated with a broad differential diagnosis, it is when those diagnoses have been ruled out do we need to consider the rare and unique diagnosis, particularly in women. Paraneoplastic cerebellar degeneration due to an underlying cancer should be included in the differential diagnosis when all other testing has ruled out other diagnoses, and now we are looking for a cancer. In such cases, providers should focus on breast and gynecologic cancer and order an autoimmune panel to confirm our diagnosis. While the prognosis is not good despite treatment for PCD, we need to be vigilant for atypical presentations, do the full work up and learn from each case.