Nodular lesions are larger and deeper than macules and papules, mostly invading deeper down into the dermis and reaching the subcutaneous tissue in severe cases. The surface is semicircular and smooth. The surface of inflammatory nodules is red, painful and angular, with a diameter of 0.5 to 5 cm. late nodules often break down, such as late syphilis nodular lesions, skin tuberculosis nodules are ulcerated and scarred. The nodules have deeper histopathological changes mostly in the deep dermis and can invade the subcutaneous fat layer, so they can be accompanied by lipid membrane and vascular type changes. The emetic has a slight pathological change in the superficial dermis, which differs from the spotted rash and papule pathological changes in the epidermis and superficial dermis. Depending on the etiology, nodules can be limited, asymmetrical, and few in number; they can also be systemic, symmetrical, and few or sparse in number. Nodular dermatoses generally have mild acute systemic symptoms, slow onset and relatively long course, such as cutaneous tuberculosis, syphilis, and erythema nodosum chronic migrans. Therefore, they are clinically different from maculopapular and papular skin diseases. Nodules are classified as inflammatory or non-inflammatory. What are the symptoms that are easily confused? 1. Multiple nodules Multiple nodules of the thyroid are a type of thyroid nodule. Thyroid nodules are a very common condition, especially among middle-aged women. Thyroid nodules are divided into two categories: benign and malignant, with benign nodules accounting for the majority of cases and less than 1% of malignant nodules. A variety of clinical thyroid disorders, such as thyroid degeneration, inflammation, autoimmunity, and neoplasia, can manifest as nodules. Thyroid nodules can be solitary or multiple. Multiple nodules have a higher incidence than solitary nodules, but solitary nodules have a higher incidence of thyroid cancer. 2.Single solid nodule Necrosis occurs in the center of granulomatous nodules, but not calcification. When the lesion spreads to the periphery, it may cause enlargement and suppuration of bronchial and mediastinal lymph nodes, and even pleurisy. Cutaneous budding bacteriosis presents as solitary or multiple cutaneous granulomas that eventually liquefy and necrosis and ulcerate in the center. The pathogen of cryptococcosis is Cryptococcus novelis, which mainly affects the brain, meninges, paranasal sinuses, as well as lungs, spleen, muscles, joints, and skin, causing dysmotility, circling movement, abnormal behavior, lameness, and nasal leakage in sick dogs. On autopsy, there were small foci of suppuration in the paranasal sinuses, turbinate, nasal cavity, and brain, and mucopurulent inflammation of the meninges. Subcutaneous granulomas were seen in the ears, eyelids and feet. 3. Fibrous calcified nodules Symptoms of calcified fibrotic nodules of the organism, mostly in the lungs. Diagnosis can be made by imaging examination. 4, pseudotuberculous nodules After 10 days of acute worm egg nodules, the capillaries in the eggs die, the eggs and necrotic material are removed, absorbed or calcified, and the macrophages in the lesion diffuse into epithelioid cells and foreign multinucleated giant cells, forming granulomas similar to tuberculous nodules, called pseudotuberculous nodules.