Nodule (pl.: noduli; synonym: small nodule; ICD-10-GM R21: skin rash and other nonspecific skin eruptions) in dermatology refers to a small nodule on skin or mucosa.
The nodule appears as a solid elevation of the skin:
- Nodule (nodule; pl: noduli): circumscribed tissue solidification protruding into or above the skin 0.5-1.0 cm
- Nodus (nodule; pl: nodi): circumscribed in or above the skin protruding tissue consolidation > 1.0 cm
Note: papules: circumscribed skin elevation < 1.0 cm in diameter; plaques: planar elevation > 1.0 cm in diameter.
The nodule belongs to the so-called primary florescences. These are skin changes that are the direct result of a disease.
Most frequently nodules occur in the tissue of the skin. Usually they can be palpated. However, they can also be found in organs such as the lungs, liver, heart or brain.
One can distinguish the following forms depending on the localization of nodules in the skin layers:
- Epidermal nodules – the nodules occur in the stratum corneum (horny cell layer) or stratum spinosum (prickle cell layer) of the epidermis (epidermis)
- Cutaneous nodules – the nodules occur in the corium (dermis).
- Epidermo-cutaneous nodules – the nodules occur in the stratum corneum or stratum spinosum of the epidermis as well as in the corium (mixed form)
Nodules or nodi can be the symptom of many diseases (see under “Differential diagnoses”).
Course and prognosis: Some nodules regress spontaneously (by itself). If the cause of the nodule is harmless, no treatment is necessary. Nodules located in internal organs are removed by surgery if malignancy (malignancy) is suspected.