👉 Illymia, a condition marked by swelling or enlargement in the skin without a cause, is the most frequent form of hereditary dermatosis. Nodyacne refers to the appearance of this abnormality. It's characterized by a swollen area that can appear anywhere on the body, from face and lips to arms and legs. Detailed definition: Illymia refers to a condition marked by swelling or enlargement in the skin without a cause. Nodyacne is a term used specifically for the abnormality described above.