We are familiar with liver cancer and lung cancer, but I am afraid that squamous adenocarcinoma is a bit unfamiliar, but I often hear professionals mention it. Adenocarcinoma is a malignant tumor of the glandular epithelium, which may have a blistering, papillary, or solid growth pattern. It is often associated with mucus production, and detection of mucus requires special staining, especially in poorly differentiated tumors. Detection of mucus is sometimes able to distinguish solid adenocarcinoma from other large cell carcinoma with the same morphological presentation. What is squamous cell carcinoma? Squamous cell carcinoma is a malignant tumor of the epidermal cells of the skin. The incidence is about 8% of eyelid malignancies. It is mostly seen in elderly people over 50 years old. There are more men than women. It occurs in the spiny cell layer of the skin at the junction of the eyelid skin and conjunctiva. It begins as a nodule, similar to basal cell carcinoma, but with abundant keratin. As the tumor progresses, it may become painful, especially when it invades the superior and inferior orbital nerves. What is the difference between squamous carcinoma and adenocarcinoma? First of all, their growth sites are different. Squamous carcinoma occurs in squamous epithelial cells and often occurs in the parts of the body covered by the original squamous epithelium, such as skin, mouth, lips, cervix, vagina, esophagus, larynx, penis and so on. Adenocarcinoma occurs in glandular epithelial cells, mostly in the stomach, intestines, breast, liver, thyroid, salivary glands, bronchi and uterine body. Secondly, their clinical manifestations are also different. Squamous carcinoma has different degrees of differentiation and a longer course of disease, but generally grows more slowly. Squamous carcinoma is prone to metastasis in the late stage and usually metastasizes first through the lymphatic tract and only in the late stage does it metastasize in the bloodstream. Adenocarcinoma grows faster and has a shorter course. The tumor is infiltrative and often has poor boundaries with normal tissues, poor mobility, or even fixed. In advanced stage, it may invade skin, muscle, nerve and bone tissue, which may cause ulceration on the surface of tumor, pain and difficulty in opening mouth.