Pangender /pan 'jendər/ is a term for people who feel that they identify with all genders available to them. This does not inherently include closed genders that are culture specific. Pangender is a non-binary gender as it means one does not identify solely as a women or man. It can have a great deal of overlap with genderqueer.
Pangender individuals are usually happy living "in between" and have no desire to live exclusively as any specific gender. Some pangender people may or may not use the transgender label. Some may identify as trans masculine or trans feminine, often shortened to trans masc or trans femme. Keep in mind that gender identity is separate from gender expression, and pangender people can have widely varying outward appearances. Being pangender does not necessarily mean that someone will appear androgynous. Pronouns do not correlate to gender either, and pangender people use a wide variety of pronouns. Always make sure to ask what someone's pronouns are if you're unsure. They/Them is a good neutral ground to work from.
Because gender identification is so closely intertwined with sexual gratification in western culture, the sexuality of pangender individuals is difficult to discuss. There are newer terms, such as Diamoric, that can apply to non-binary people's attraction which can help clear up confusion.
Pangender and transgender individuals are sometimes dismissed as fetishists ignoring the issue of gender identification altogether. Always remember that it does not mean someone else is wrong or invalid just because you may not understand their identity. :)