Diagnosis of common skin diseases includes the following: 1. Blood work to determine if it is a viral or bacterial infection. In the case of bacterial infections, such as dermatophytosis, elevated white blood cells and neutrophil fraction may be seen. In the case of viral infections, there may be a decrease in white blood cells and an increase in lymphocyte fraction. 2. fungal microscopy and culture. Fungal microscopy is performed for fungal infections such as ringworm, ringworm, and Malassezia folliculitis. Fungal cultures are performed for diseases such as onychomycosis that are not easily detected by microscopy. 3. Skin CT, dermatoscopy, and skin histopathology are performed to clarify the name of the disease and the genus of the disease.