Nodules are usually multiple, forming a multinodular goitre (Figure 50.11). Occasionally, only one macroscopic nodule is found, but microscopic changes will be present throughout the gland; this is one form of a clinically solitary nodule. Nodules may be colloid or cellular, and cystic degeneration and haemorrhage are common, as is subsequent calcification. Nodules appear early in endemic goitre and later (between 20 and 30 years) in sporadic goitre, although the patient may be unaware of the goitre until his or her late 40s or 50s. All types of simple goitre are more common in the female than in the male owing to the presence of oestrogen receptors in thyroid tissue.