Related to its physical properties, heliox gas seems to have a strong and pronounced effect when used in patients with severe lower airway obstruction. However, in the absence of severe lower airway obstruction, there is no advantage to using heliox instead of oxygen as a vehicle of nebulization.

Riedel's thyroiditis is a rare, chronic inflammatory disease of the thyroid gland. The aggressive fibrosis with extension beyond the thyroid into adjacent tissues contrasts with the diffuse, but intracapsular fibrosis of Hashimoto's thyroiditis. Most current studies refute the possibility of progression from a highly fibrosing form of Hashimoto's thyroiditis to a Riedel's thyroiditis based on the distinct clinical and laboratory data, although an unknown immunological basis is suggested for both diseases. The authors describe a patient with Riedel's thyroiditis, probably associated with Hashimoto's thyroiditis, sent to surgery because her cytological examination suggested thyroid malignancy. This patient had clinical and laboratory features of hypothyroidism and very high titers of antimicrosomal and antithyroglobulin antibodies, which decreased after surgery. Pathology studies disclosed Riedel's thyroiditis with intense lymphocytic infiltration suggestive of Hashimoto's thyroiditis. Quantitative immunohistochemical studies were not able to distinguish between both diseases.

Incidentalomas of the thyroid are common small nodules found occasionally during imaging procedures. Their pathological nature is generally benign, but about 4% may harbour malignant tissue. Most current studies only suggest clinical follow-up, but there are no data about the natural history of malignant incidentalomas. The authors describe a patient with multiple incidentaloma of the thyroid submitted to fine-needle aspiration biopsy because his larger nodule grew 50% in 3 months at ultrasonographic follow-up. The cytological examination suggested thyroid malignancy in this nodule and surgical pathology showed multicentric papillary carcinoma. This case suggests that the larger diameter of a malignant incidentaloma may change rapidly. If more time had been spent before repeating the ultrasonography, the volume could have changed even more and the prognosis could have been changed as indicated by most prognostic score indexes.