Necrosis occurs in the center of granulomatous nodules, but not calcification. When the lesion spreads peripherally, 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. The main cause of solitary solid nodules is fungus. The following diseases may also be the cause of solitary solid nodules: 1. CD30 positive cutaneous T-cell lymphoma CD30 positive cutaneous T-cell lymphoma, also known as primary CD30 positive cutaneous T-cell lymphoma, is a solitary or limited skin lesions that tend to ulcerate (50%) and regress spontaneously (25%). It is rare in children and more common in males than females. Malignant granulosa cell tumors are relatively rare and often occur in the skin or subcutaneous tissues, and rarely in the bladder and larynx. There are two types: one is clinically malignant and histologically benign; the other is clinically and histologically malignant. Ulcers often occur. The more recognized criteria for malignancy are: (1) benign pathology, but clinical recurrence or metastasis; (2) volume greater than 4-5 cm, nuclear division 2/10 HPF, spindle cell tumor, large nuclei with obvious nucleoli, necrosis, rapid growth or recurrence, all six phenomena need not be present.