Sinonasal Sarcoidosis Presenting as an Aggressive Nasal Destructive Lesion Mimicking Malignancy: A Diagnostic Challenge.

Sarcoidosis is a multisystem granulomatous disease that commonly involves the lungs, with rare involvement of the sinonasal region. We present the case of a 64-year-old Asian female with a five-month history of painless nasal swelling and deformity. Imaging revealed an aggressive, fluorodeoxyglucose (FDG)-avid lesion involving the frontal sinuses, nasal septum, hard palate, and adjacent soft tissues, raising concern for malignancy such as lymphoma or squamous cell carcinoma. However, multiple biopsies from the nasal lesion, mediastinal lymph nodes, and a subcutaneous elbow nodule revealed non-necrotising granulomatous inflammation. A diagnosis of stage II pulmonary sarcoidosis with nasal and cutaneous involvement was confirmed through a multidisciplinary team review. This case highlights the diagnostic challenge posed by sinonasal sarcoidosis, which can mimic malignancy both clinically and radiologically, especially in the absence of systemic symptoms related to sarcoidosis. Early consideration of sarcoidosis in the differential diagnosis of destructive sinonasal lesions can help avoid unnecessary investigations and guide appropriate management.