To document a case of Purkinje cell cytoplasmic antibody type 1 (PCA-1, or anti-Yo) associated paraneoplastic cerebellar degeneration (PCD) in a woman with gastric adenocarcinoma

Subacute cerebellar degeneration is a paraneoplastic syndrome often preceding the diagnosis of cancer. Multiple antibodies have been linked with it, including PCA-1 (most commonly), PCA-2, PCA-Tr, and anti-mGluR1. PCD is usually associated with gynecologic cancer, small-cell lung cancer, or lymphoma. Gastric adenocarcinoma has infrequently been reported with PCA-1 + PCD in men; we could not identify published reports in women.

Case report, literature review

A 56-year-old woman with history of gastric sleeve surgery presented with several weeks of progressive dysmetria, opsoclonus, and scanning dysarthria. Serological studies revealed normal thiamine, mildly elevated ANA (1:320) and SSA antibodies, and low titer GAD65 antibodies (0.10 nmol/L).  CSF evaluation demonstrated a lymphocytic pleocytosis (66 nucleated cells), elevated protein (63 mg/dL), and 10 CSF-specific oligoclonal bands. An incidental pineal cyst was noted on brain MRI. 

CT chest/abdomen/pelvis showed multiple masses involving the gastrohepatic and gastrocolic ligaments, anterior mesentery, and endometrial canal. Per gynecology, a pelvic ultrasound showed a fibroid uterus and a benign ovarian cyst. A prominent supraclavicular lymph node was biopsied, revealing poorly differentiated adenocarcinoma, likely upper GI primary.  Biopsy of a gastric ulcer revealed poorly differentiated adenocarcinoma with signet ring cell features.  Ultimately, high titer PCA-1 antibodies were identified in the serum (1:15630), as well as CSF (1:512).

PCD is infrequently associated with gastric adenocarcinoma. We report a case of a middle-aged woman with PCA-1 positive PCD and gastric adenocarcinoma. Immunotherapy targeted to the paraneoplastic syndrome was ineffective.