Primary Signet Ring Cell Carcinoma of the Lung: A Rare Histologic Variant With Distinct Radiologic Presentation.

Signet ring cell carcinoma (SRCC) is a rare and distinct subtype of adenocarcinoma. It can arise in various organs, including the stomach, colon, breast, bladder, and prostate. It may also occur as a primary pulmonary tumor. We report a case of a 65-year-old woman with no significant medical history, who presented with a two-month history of dyspnea and hemoptysis, associated with weight loss. A chest CT scan revealed a locally advanced pulmonary mass with mediastinal lymphadenopathy and bilateral pulmonary metastases. A biopsy was performed and confirmed a diagnosis of pulmonary-origin signet ring cell adenocarcinoma. Given the patient's general condition, chemotherapy with weekly paclitaxel and carboplatin (AUC2) was initiated. At the first evaluation after three cycles, the disease was stable. The patient subsequently developed a respiratory infection due to a multidrug-resistant organism, and despite appropriate antibiotic therapy, she passed away because of the infection. Primary SRCC of the lung remains a diagnostic and therapeutic challenge, with poor prognosis despite early intervention. The rapid clinical decline observed in this case highlights the aggressive nature of the disease and the importance of supportive care.