Atypical Sjögren-Like Presentation as a Paraneoplastic Manifestation of Metastatic Parotid Adenocarcinoma

Paraneoplastic Sjögren-like syndrome is a rare extraglandular manifestation of occult malignancy that can closely mimic primary autoimmune disease, leading to delayed diagnosis of the underlying neoplasm. While most reported cases are associated with hematological malignancies, its occurrence in the context of solid tumors, particularly salivary gland carcinomas, is exceptionally rare and poorly characterized. We report a 43-year-old male presenting with progressive dyspnea, constitutional symptoms, and severe polyserositis, initially suggestive of primary Sjögren's syndrome (SS) based on objective sicca findings, including severely reduced lacrimal secretion on the Schirmer test and clinically observed asialia, in conjunction with positive anti-SSA antibodies. Imaging showed persistent pulmonary lesions and pleural effusions, while bronchoalveolar lavage revealed markedly elevated galactomannan levels, suggesting probable pulmonary aspergillosis. Despite immunosuppressive therapy, no clinical improvement was observed. Further evaluation, including surgical biopsy, demonstrated metastatic adenocarcinoma of probable salivary gland origin. The final diagnosis was stage IV parotid adenocarcinoma with pulmonary metastases and paraneoplastic Sjögren-like syndrome. The patient received one cycle of chemotherapy but subsequently deteriorated and died. Paraneoplastic Sjögren-like syndrome is exceptionally rare and characterized by heterogeneous clinical presentations, often lacking classic histopathological findings. Red flags such as rapid progression, systemic involvement, and poor response to standard therapy should prompt evaluation for occult malignancy. This case highlights the importance of recognizing atypical Sjögren-like presentations as a probable paraneoplastic phenomenon. Early identification of warning signs may facilitate timely diagnosis of underlying malignancy and impact clinical outcomes.