Final answer:
A nodule can form on the skin due to inflammation in response to clogged hair follicles, infections, immune reactions like contact dermatitis, or as a result of cell damage from conditions such as skin cancer.
Step-by-step explanation:
A nodule is a type of lesion that can appear on the skin due to various underlying conditions. These dome-shaped structures can be caused by an inflammatory response to an infection, such as when hair follicles become clogged and create a perfect environment for bacterial growth. For instance, acne is one such condition where clogged, sebum-filled pores become inflamed, leading to cellular damage and the potential development of nodules. Inflammation goes deep into the skin with the formation of an acne nodule. Another cause can be related to a skin condition or an immune response, such as contact dermatitis, which can arise from exposure to certain materials like latex resulting in a delayed-type hypersensitivity reaction.
Localized inflammation of the skin can also lead to nodule formation. This can happen when the dermis and subcutaneous layers become inflamed, making the skin red, warm, and painful to the touch. Additionally, skin cancer is a severe medical condition where abnormal cell growth can lead to the creation of cancerous nodules, often as a result of DNA damage from exposure to UV radiation.
In summary, nodules are complex lesions with various causes including infections, immune responses, and even skin cancer. It is essential to understand the underlying cause to treat the nodule effectively.