Overcoming diagnostic pitfalls in primary gastric squamous cell carcinoma: the imperative of adequate sampling in an elderly female patient, case report

Objective To report the diagnosis and treatment of a rare case of primary gastric squamous cell carcinoma (PGSCC) in an elderly female, and to explore the diagnostic pitfalls and individualized treatment strategies. Methods We conducted a retrospective analysis of the clinical, imaging, endoscopic, and pathological data of a 77-year-old female patient. The evolution of the diagnosis from the initial “possible adenocarcinoma” to the final diagnosis of “ squamous cell carcinoma” was emphasized. Results The patient presented with abdominal pain. The first endoscopic biopsy, due to the limited tissue sample, showed immunohistochemistry results of CKpan (+), CK7(+), MUC5AC (focal+), and Ki-67(partly+), favoring a diagnosis of adenocarcinoma. A subsequent deep biopsy with complete immunohistochemistry (CK5/6+, P40+, P63+) confirmed the diagnosis of gastric squamous cell carcinoma. Given the patient’s advanced age, poor physical condition, and refusal of surgery, a palliative treatment plan of “Raltitrexed + Sintilimab” was finally decided upon after a multidisciplinary consultation. Conclusion This case highlights the importance of adequate sampling in the diagnosis of gastric squamous cell carcinoma to avoid misdiagnosis due to limited specimens. It also provides a potential treatment option of immune therapy combined with low-dose chemotherapy for elderly patients with gastric squamous cell carcinoma who are not suitable for surgery.