The incidence of mucormycosis, an opportunistic infection, has been increasing worldwide in recent years. This is primarily due to the spread of coronavirus disease 2019 and the increase in the number of at-risk populations. Risk groups include patients with conditions or diseases, such as diabetes, neutropenia, organ or stem cell transplantation (on immunosuppressive therapy), trauma and burns, hematological disorders, and steroid therapy. The basis of successful treatment includes early diagnosis based on the detection of the first nonspecific signs of the disease in patients at risk, rapid verification of pathogens, earliest possible start of etiotropic therapy, and prompt and aggressive surgical treatment (necrectomy). This study presents a clinical case of rhino-orbital mucormycosis in a child at risk. The patient had Alagille syndrome and was followed up from the age of 2 years. The syndrome is characterized by an insufficient number or the small diameter of the intrahepatic bile ducts that remove bile from the liver and lead to the development of liver cirrhosis. Liver transplantation is the only radical treatment method for liver cirrhosis in the absence of gross defects. By the age of 8 years, the syndrome led to liver cirrhosis, and in 2020, hepatectomy was performed, including orthotopic transplantation of a liver fragment from a related donor (aunt). The patient subsequently received immunosuppressive therapy. The article also described the changes in the clinic and imaging methods and stages of treatment by day. Clinical manifestations of mucormycosis appeared on day 6 of hospitalization, that is, edema of the left lower eyelid. The severe general condition of the child did not allow for early surgical treatment with the excision of necrotic tissues. Unfortunately, the patient died. Thus, possible errors in diagnosis and treatment were analyzed.
