Malignant tumors of the eyelid are malignant invasive tumors that originate in the eyelid skin and its appendages and include mainly basal cell carcinoma, squamous cell carcinoma, sebaceous gland carcinoma, and malignant melanoma. The incidence of these tumors accounts for about 32.6% of all eyelid tumors and more than 95% of eyelid malignancies. Malignant tumors of the eyelid not only damage the appearance and affect vision, but also cause local infiltration and distant metastases, which can endanger the life of the patient. The presentation of eyelid malignancies is complex and varied, and clinical features alone can easily lead to misdiagnosis and missed diagnoses, delaying the best time for treatment. Fine-needle aspiration biopsy (FNAB) can be used preoperatively to determine the nature and type of tumor, especially the status of local lymph node metastases, and can help guide surgical planning, but it has not received the attention it deserves. Unless the patient is unwilling to accept it, surgical resection is currently the most important method for treating eyelid malignancies, but scholars both at home and abroad still disagree greatly on the specific surgical plan selection and tumor margin control. The frozen margin-controlled surgical approach (Mohs micrographic surgery, MMS) can ensure the maximum preservation of normal eyelid tissues while ensuring tumor eradication and is worth advocating and promoting. The repair of eyelid defects after resection of tumors, especially giant tumors, is one of the major challenges in the treatment of eyelid malignancies, which requires expertise in oculoplastic surgery to select a reasonable repair method based on the site, size, and extent of the eyelid defect to achieve the desired outcome of both radical treatment and functional reconstruction. The role of needle biopsy in the diagnosis and differential diagnosis of eyelid tumors Fine needle aspiration cytology (FNAB) is a method in which a fine needle (usually a 7-gauge needle) is used to penetrate the tumor and aspirate a certain amount of tumor tissue for smear examination to determine the nature of the tumor. As a diagnostic tool, puncture biopsy has been highly controversial. Due to the limitations of the procedure, the amount of tissue that can be obtained is small, sometimes only a few cells, and the cells are easily distorted or broken during the aspiration process, making it very demanding for the reader and sometimes impossible to confirm the diagnosis; even if sufficient tissue is obtained, the diagnosis rate is still not high enough compared to postoperative pathological examination by paraffin section. However, in the diagnosis and differential diagnosis of eyelid tumors, puncture biopsy has unique advantages: the superficial site of the eyelid tumor does not require ultrasound or imaging guidance, which makes it easier to operate; the puncture needle does not pass through normal tissue, so complications such as bleeding and infection are rare and generally do not lead to tumor spread; when applying the traditional surgical method of non margin control, the pathological type of the tumor after the needle puncture can be used to determine the extent of resection of the tumor surrounding the tumor. It is useful for determining local lymph node metastasis and the need for lymph node dissection; it is especially suitable for diagnosing tumors that obviously invade the conjunctiva, and it is easy to obtain more specimens to make a clear diagnosis. Puncture biopsy is an important method for preoperative diagnosis of malignant tumors of the eyelid because it is easy to perform, has minimal damage, and is quick to diagnose. It has been reported that the diagnostic rate of puncture biopsy for eyelid and orbital tumors in foreign countries is as high as 94%, which is close to the diagnostic rate of postoperative paraffin section case examination. However, in China, puncture biopsy is rarely applied at present, and only one report was retrieved. Therefore, the role of needle biopsy in eyelid malignancies should be fully valued and selected for application in due course. Second, the important role of Mohs method in eyelid tumor resection should be emphasized. Surgical resection is the most effective and surest treatment for eyelid malignancies. The basic principle of surgical treatment of ocular tumors should be to remove the maximum amount of tumor tissue to ensure the cure rate. However, because the eyelid has a special anatomy, unique function of opening and closing, and tear secretion, excessive removal of eyelid tissue not only damages the appearance and affects movement, but also causes serious complications such as corneal clouding and even blindness. Therefore, there has been considerable controversy regarding the extent of margin excision for eyelid malignancies. It has been suggested that different eyelid malignancies have different infiltrative and invasive abilities, and the extent of surgical resection should be formulated according to the histologic origin and pathologic subtype of the tumor. (1) Basal cell carcinoma: 3 mm for nodular type, 5 mm for infiltrative type, and 8 mm for sclerosing type. (2) Squamous cell carcinoma: 4-5 mm. (3) Adenocarcinoma of the lid: 5-9 mm. (4) Malignant melanoma: 7-10 mm. However, if this criterion is followed, even if the lid adenocarcinoma detected early is only 3 mm in diameter, tumor excision will inevitably result in an eyelid defect of nearly 13-21 mm in diameter, making repair very difficult. How to maximize the preservation of normal eyelid tissues with complete resection of the tumor has become a key concern in the current resection and repair of eyelid malignancies. As early as the 1930s, Dr. Mohs discovered that injecting zinc chloride into the skin could cause tissue fixation and necrosis, allowing its microstructure to be maintained and thus distinguished from normal skin, thus giving birth to the Mohs method, which is widely used in the surgical treatment of skin cancer. However, zinc chloride ointment is highly irritating and can easily cause conjunctivitis and even keratitis when used in eyelid skin lesions. In view of this, Dr. Mohs removes the unfixed eyelid tissue and then makes frozen sections for microscopic observation to control the extent of eyelid tumor excision until all margins are negative before changing gloves and surgical instruments for further blepharoplasty, which is the Mohs method commonly used in eyelid tumor surgery today. This is the Mohs method, which is now commonly used in eyelid tumor surgery. Compared with the conventional method, which has wide margins and destroys too much normal eyelid tissue, the Mohs method ensures complete resection of the tumor while preserving the maximum amount of uninfiltrated normal tissue, which facilitates intraoperative eyelid reconstruction. More importantly, the Mohs method results are more reliable for deep or recurrent tumors, because standard surgery is performed under the naked eye, and even if the conventional extent of resection is achieved, tumor tissue may remain and there is an increased risk of local infiltration or metastasis. The Mohs method has become an increasingly popular method for the treatment of eyelid malignancies internationally, with a cure rate of 98% for primary basal cell carcinoma, compared to 93% for standard surgery, 91% for radiotherapy, and 92% for cryotherapy, especially for recurrent basal cell carcinoma, where the Mohs method can achieve a 95% cure rate, compared to 83% and 60% for conventional resection and radiotherapy, respectively. The Mohs method has increasingly become the mainstream method for the treatment of eyelid malignancies internationally, but its application in China still needs to be further promoted and popularized. However, for highly malignant lid adenocarcinoma and malignant melanoma, even if the Mohs method shows negative margins, a significant proportion of patients still develop local lymph node or distant organ metastases after surgery, which can eventually lead to death. How to improve the cure rate of these eyelid tumors, such as whether prophylactic cervical lymph node dissection is needed and whether the resection of peri-tumor tissues should be further expanded on the basis of negative Mohs method margins, still needs to be provided by clinical studies with definite evidence-based medical evidence. Immediate repair of eyelid defects after eyelid malignancy resection Eyelid malignancies often result in eyelid defects, which not only hinder the appearance, but also cause a series of symptoms such as dry eyes and corneal clouding, which seriously affect the quality of patients’ survival. There are several ways to classify eyelid defects. Clinically, they are often classified as anterior, posterior, or total defects based on the depth of the defect, with total or posterior defects being the main cause of eyelid defects due to eyelid tumor resection. On this basis, a specific repair plan is developed based on the location, extent, and degree of the defect, as well as the patient’s age. Successful eyelid reconstruction requires that the following conditions are met: (1) basic eyelid function is maintained; (2) the shape of the eyelid is maximized; and (3) complications are minimized. The key to repairing an ocular defect is lid reconstruction. The traditional method of sliding the normal lid and conjunctiva of the upper or lower lid into alignment to repair the defect has the inherent disadvantages of sacrificing a healthy lid, and the lack of support of the posterior lid layer after reconstruction can result in the development of lid entropion and contracture, as well as the need for two-stage surgery. Autologous or allogeneic tissue material is now commonly used clinically as a replacement for the posterior lid layer to enhance the stability of the repaired eyelid. Common lid substitutes include posterior auricular cartilage, allograft sclera, nasal septal cartilage, decellularized dermis, and hard palate mucosa. Autologous hard palate mucosa has moderate hardness, smooth surface, contains small glands, rich blood flow, concealed incision, and no risk of rejection with autologous graft, which has obvious comparative advantages among multiple lid substitutes and is the most widely used lid substitute at present. However, the biggest problem with lid defect repair is that all existing materials or substitutes do not have the glandular secretion function of the lid and cannot provide the active component of the tear film, which can lead to varying degrees of postoperative damage to ocular surface stability and, in severe cases, significant corneal conjunctival damage. The development of new lid substitutes or the use of tissue engineering techniques to construct artificial lids is an important direction for future basic research in eyelid repair. When repairing a total eyelid defect, if a free tissue graft is chosen for the posterior layer, a tissue graft with a good blood supply must be used for the anterior layer to ensure that the posterior layer can be viable. It is common to use a hard palate mucosa graft to repair a posterior lid defect and an adjacent flap transfer to repair an anterior lid defect. Commonly used adjacent flaps include suprabrow flaps, zygomatic-temporal flaps, nasal-cheek flaps, and superficial temporal fascial island flaps. The choice of flap should be individualized and applied flexibly. For example, malignant tumors of the eyelid are commonly seen in the elderly, so the use of a frontal suprabrow flap can take advantage of the flaccid and redundant frontal lid skin of the elderly, which can both repair eyelid defects and improve skin laxity. The treatment of malignant tumors is lifelong, and even if the tumor is completely removed with negative margins, it does not mean the end of treatment. Routinely, patients with eyelid malignancies are followed up monthly for three months after surgery in the first year, then every three months in the next year, every six months in the second year, and annually thereafter. For recurrent tumors and more malignant eyelid tumors such as malignant melanoma, adenocarcinoma of the lid, squamous cell carcinoma, and poorly differentiated basal cell carcinoma, the interval between follow-up visits should be shortened appropriately depending on the condition. The observation indexes at the follow-up examination are mainly: clinical examination of the eyes; ultrasound of bilateral preauricular, neck and parotid glands; imaging examinations such as CT of the head or abdomen. In China, due to the lack of systematic case registration system and standardized community follow-up system, coupled with the low compliance of many patients to seek medical care, a large number of oncology patients have been lost after surgery. It should be advocated to establish personal files of eyelid malignancy patients after surgery and collect detailed information so that they can be common across the country, thus ensuring that patients can receive correct and continuous treatment even if they visit different hospitals and different regions. Of course, the diagnosis and treatment of eyelid malignancies involve other multifaceted and complex issues, such as the prospect of the application of non-surgical treatment methods, the development of novel diagnostic and therapeutic methods, and research at the molecular and genetic levels. However, the issues discussed in this article are very important clinical issues that have not received sufficient attention at present. The improvement and popularization of the understanding of these issues will actively improve the diagnosis and treatment of eyelid malignancies in China and improve the prognosis and survival quality of patients.