Thyroid membrane involvement in rheumatoid nodules: a rare finding.

A 76-year-old woman with a 19-year history of rheumatoid arthritis (RA) presented with progressive cachexia and constitutional symptoms. Imaging revealed a suspicious hypermetabolic lesion in the cervical region, initially raising concerns of malignancy. Following excision, histopathology identified the lesion as a rheumatoid nodule, a rare extra-articular manifestation of RA in deep tissues like the thyroid membrane. The patient's symptoms were attributed to her autoimmune disease and cognitive decline. This case highlights the importance of considering rheumatoid nodules in the differential diagnosis of cervical masses in RA patients, potentially avoiding unnecessary surgical interventions.