What condition is suggested by a 1cm swelling adjacent to the thyroid and symptoms of weight loss and night sweats?

A 1cm swelling adjacent to the thyroid along with symptoms such as weight loss and night sweats raises concern for a malignant process, and lymphoma is particularly indicated in this scenario. Lymphoma can present as a localized mass in the neck, often with systemic symptoms like weight loss and night sweats due to the aggressive nature of the disease and its impact on the immune system.

The other options typically present with different clinical features:

• Follicular carcinoma, while a thyroid malignancy, often presents as a more indolent thyroid mass without prominent systemic symptoms such as significant weight loss or night sweats.

• Papillary carcinoma also tends to present with a thyroid nodule, but typically does not lead to such marked systemic symptoms in its early stages.

• Graves' disease is an autoimmune hyperthyroid condition characterized by symptoms like goiter, specific hypermetabolic signs (like heat intolerance), and is unlikely to present as a discrete mass alongside classic malignancy symptoms.

The combination of localized swelling with systemic symptoms strongly points towards lymphoma as the most likely diagnosis in this context.