Leptomeningeal Metastasis from Gastric Signet Ring Cell Carcinoma: A Case Report and Literature Review

Leptomeningeal carcinomatosis (LMC) is a rare and highly fatal complication of solid malignancies and is extremely uncommon in gastric cancer, particularly as an isolated metastatic lesion. This study presents a rare case of LMC in a patient diagnosed with gastric signet-ring cell carcinoma and reviews cases reported in PubMed over the last 10 years. n METHOD: We present a 43-year-old male patient diagnosed with poorly differentiated gastric signet-ring cell carcinoma and elevated CA19-9 levels. His initial staging was consistent with locally advanced disease (CT4aN2M0). The patient received neoadjuvant FLOT chemotherapy, followed by total gastrectomy. In addition, articles published in PubMed over the last 10 years were systematically reviewed to identify cases of LMC associated with gastric cancer.

The final pathology from the gastrectomy revealed ypT3N3 disease. Three weeks after surgery, the patient developed new-onset headaches and progressive confusion, with a Mini-Mental State Examination score of 23/30. Contrast-enhanced brain MRI did not reveal any mass lesion but showed subtle hyperintensity in the cerebral peduncle region. CSF cytology confirmed LMC, demonstrating malignant signet-ring cells. After detailed consultation, the patient declined targeted therapy and transitioned to home palliative care, passing away two weeks after the diagnosis. The literature review identified 18 cases of LMC associated with gastric cancer. Clinical presentations were largely non-specific, including headache, nausea/vomiting, and confusion. Outcomes were uniformly poor, with survival typically measured in weeks.

In patients with gastric cancer, clinicians should maintain a high index of suspicion for LMC when new neurological symptoms are detected, even in the absence of other metastatic disease on systemic workup. Cerebrospinal fluid cytology remains as an important test for confirming the diagnosis.