特发性炎性肌病（IIM）是一组以肌肉炎症为特征的疾病，可能导致肌肉无力和损伤。这些疾病的确切原因尚不明确，因此被称为“特发性”。这些条件也被认为是自身免疫性疾病，其中身体的免疫系统错误地攻击自身组织。

特发性炎性肌病的主要类型包括：
1. 皮肌炎（DM）：这种类型涉及肌肉无力以及独特的皮肤皮疹。
2. 多发性肌炎（PM）：这涉及肌肉炎症和无力，但没有皮肌炎特有的皮肤皮疹。
3. 包涵体肌炎（IBM）：这种类型导致肌肉无力和消耗进展，通常与肌细胞内形成包涵体相关。
4. 坏死性自身免疫肌病（NAM）：其特点是严重的肌肉无力和没有显著炎症的肌细胞死亡的证据。
5. 少儿肌炎（JM）：这种类型影响儿童，通常包括皮肌炎或多发性肌炎中见到的症状。

每种类型的IIM都有其独特的特征，并可能需要不同的治疗方法。

Idiopathic inflammatory myopathies (IIM) are a group of diseases characterized by inflammation of the muscles, which can cause muscle weakness and damage. The exact cause of these disorders is unknown, which is why they are termed "idiopathic." These conditions are also considered autoimmune diseases, where the body's immune system mistakenly attacks its own tissues.

The main types of idiopathic inflammatory myopathies include:
1. Dermatomyositis (DM): This type involves muscle weakness along with a distinctive skin rash.
2. Polymyositis (PM): This involves inflammation and weakness in the muscles but without the skin rash characteristic of dermatomyositis.
3. Inclusion body myositis (IBM): This type leads to progressive muscle weakness and wasting, and it is often associated with the formation of inclusion bodies within the muscle cells.
4. Necrotizing autoimmune myopathy (NAM): This is characterized by severe muscle weakness and evidence of muscle cell death without significant inflammation.
5. Juvenile myositis (JM): This type affects children and often includes symptoms seen in dermatomyositis or polymyositis.

Each type of IIM has distinct features and may require different treatment approaches.