Paraneoplastic Cerebellar Degeneration in a Patient with Pseudomyxoma Peritonei and Breast Cancer: Case Report and Literature Review

The case of a 31-year-old woman with progressive cerebellar degeneration preceding by several months the diagnosis and treatment of breast cancer initially and pseudomyxoma peritonei (PMP) with evidence of causative association with the latter is presented. Despite various chemotherapeutic and surgical manipulations, the patient did not substantially improve and succumbed 20 months following initial diagnosis of the neurological disorder. Interestingly, neurological symptoms partially regressed transiently only after surgical debulking of the PMP and not after the remission of breast cancer after various chemotherapeutic regimens suggesting an etiological relationship of the former and the cerebellar degeneration. Early recognition and appropriate therapy of this rare complication of PMP is imperative as it may be crucial for the outcome. Paraneoplastic neurological syndromes (PNS) are rare immune-mediated syndromes occuring in less than 1% of patiens with breast cancer (1, 2). Their pathogenesis is not well understood and their clinical presentation and course vary. However, specific autoantibodies targeting onconeuronal antigens, such as anti-Hu, anti-Ri and anti-Yo may be identified in the serum and cerebrospinal fluid (CSF) in some patients (3-5). These syndromes may precede diagnosis of cancer by months or years, therefore their diagnosis could be challenging and is usually performed in two steps. The exclusion of more common causes of neurological dysfunction and a high degree of clinical suspicion are both required and depend on the knowledge of the association of neurological symptoms and specific tumor types. Pseudomyxoma peritonei (PMP) is a rare disease commonly diagnosed incidentally at laparotomy and characterized by disseminated mucinous ascites and peritoneal implants. The etiology of the disease remains unclear: it usually involves the appendix (6), while other sites include the ovaries and the pancreas (7); however, most cases of cystic ovarian mucinous tumors associated with PMP are associated with metastases from an appendiceal tumor (7). Radical surgical debulking and appendicectomy remain the cornerstones of treatment, although the optimal management of the disease remains controversial. Intraoperative and intraperitoneal chemotherapy have also been attempted and the clinical outcome varies widely among the benign and the malignant forms and between the different treatment modalities.