Patients with leukemia usually need to undergo chemotherapy. However, before, during and after chemotherapy, the patient is prone to a decrease in whole blood cells, resulting in serious complications such as anemia, bleeding, and infection, which can be dangerous if surgery is performed during this time, but also dangerous if surgery is not performed when combined with sinusitis. Due to the low resistance of the patient, sinusitis is mostly mycosis fungoides or even invasive mycosis fungoides, which often erodes the surrounding bone causing destruction of the surrounding bone, spreads to the orbit causing loss of vision and even spreads to the skull causing intracranial infection. Patients are often faced with a dilemma: on the one hand, surgery is not possible, and there is a risk of aggravation or even deterioration of the disease; on the other hand, hematologic patients with low immune function, difficult wound healing, low platelets, and difficult bleeding are often contraindicated in conventional surgery, and if surgery is performed, they will face the risk of intraoperative and postoperative bleeding and aggravation of infection. However, in order to improve the patient’s prognosis, nasal endoscopic sinus surgery can also be performed for hematologic patients when conditions permit, taking advantage of the characteristics of the disease. Case: The patient was treated with chemotherapy for leukemia and bilateral sinusitis was found during chemotherapy. The pathology was confirmed to be invasive mycosis fungoides. The patient recovered well and recently completed the bone marrow transplantation. The experience of this patient suggests that sinus surgery is possible in patients with leukemia and that the timing of surgical intervention is important, as in this patient, early nasal endoscopic surgery might have reduced the extent of necrotic lesions. Therefore, if sinusitis is detected during chemotherapy, early surgical intervention is recommended to achieve better results. However, this requires the surgeon to weigh the pros and cons with the patient and family and to choose the least invasive surgical procedure possible.