## 2 Related Studies  
Skin lesions show similar appearances to a congenital nevus (mole), which poses difficulties in the early diagnosis of skin diseases via visual inspection by humans. Moreover, differences among various types of skin diseases and lesions are difficult to differentiate, which necessitates a precise analysis of skin lesions [24]. 1. Actinic keratosis (AKIEC) presents as scaling pink/red macules or papules on areas of chronic sun exposure and is a precancerous condition of the skin that may evolve into squamous cell carcinoma (SCC). 2. Basal cell carcinoma (BCC), a malignant neoplasm derived from non-keratinizing cells originating in the epidermis and its basal layer, is locally invasive, and its metastasis is rare. BCC and SCC are the two most common subtypes of nonmelanoma skin cancer. 3. Benign keratosis-like lesions (BKLs) are benign tumors that develop on the skin, characterized by excessive formation of keratinized tissue resulting in a thick, irregular epidermal layer. Although they are generally not life-threatening, accurate diagnosis is necessary as they can be mistaken for malignant tumors. 4. Dermatofibroma refers to a benign tumor of the skin composed of fibrocytes and fibers forming connective tissue, often occurring in conjunction with other types of skin tumors. 5. Malignant melanoma (MEL) is a type of skin tumor caused by the malignant transformation of melanocytes; it may be congenital or acquired. Although MEL primarily develops on the skin, it can originate from melanocytes located in the eyes or in mucosal membranes lining the anus, nose, and esophagus. 6. Melanocytic nevi (NV) refer to pigmented lesions of the skin and typically occur in children or adolescents, and occasionally at birth. NV comprise a cluster of melanin-producing cells known as melanocytes. As time progresses, the number of nevi may increase, or those already present may increase in size or become darker. 7. Vascular lesions (VASC) are lesions such as nevus flammeus, facial flushing, telangiectasia, and hemangiioma, which are caused by hemoglobin oxidation and triggers severe oxidative stress in blood cells and vessels. They appear in various forms, such as facial flushing, nevus flammeus, and rosacea. If melanocytic nevi is suspected of being malignant melanoma, excisional biopsy is essential and, in the case of BCC or SCC, biopsy is performed to plan subsequent treatment. The examination requires approximately one week and incurs a high cost. To resolve this problem, researchers are attempting to replace conventional methods of skin disease diagnosis with medical AI [25; 26; 27]. Figure 1 shows eight types of skin lesions. [PERSON] et al. [28] proposed an integrated diagnostic framework that combines the skin lesion boundary segmentation stage and the multiple skin lesion classification stage. They used a full resolution convolutional network to segment skin lesion boundaries from whole dermoscopic images; additionally, they used Inception-v3, ResNet-50, Inception-ResNet-v2, and DenseNet-201 to classify segmented skin lesions. The classification performance of each classifier model in terms of accuracy was 88.05%, 89.28%, 87.74%, and 88.70%, respectively, and the final results were obtained by synthesizing the accuracy of these classifiers. Since this framework uses multiple classifiers, the initial setup for experiments incurs high costs and the training and inference processes are time-consuming. [PERSON] et al. [29] classified skin lesions hierarchically into melanocytic and non-melanocytic lesions based on their origins; subsequently, they were further classified into benign or malignant lesions depending on the malignancy degree. The classification method used may be similar to that used for binary tree problems, and DenseNet-161 and ResNet-Inception were used as the architectures of the input image encoder.