Objective To report a case of Niemann-Pick disease type C (NPC) after radiotherapy and chemotherapy for sellar seminoma, and improve the understanding of Niemann-Pick disease (NPD).

Methods The 4-year medical history of a teenager who developed hypersituitarism, severe liver damage, hepatosplenomegaly, and secondary diabetes mellitus after hormone replacement therapy after resection of sellar seminoma, radiotherapy and chemotherapy in June 2021 was retrospectively analyzed.

Results The patient was a young female. After the resection of seminoma in sellar region and radiotherapy and chemotherapy, she gradually developed varying degrees of hematocytopenia, abnormal lipid metabolism, abnormal liver function, and enlargement of the liver and spleen. Until bone marrow aspiration was performed that 2% Niemann-Pick cells were found, the final diagnosis of NPC was made. After blood transfusion, liver protection, insulin hypoglycemic, hormone replacement and other symptomatic treatment, the indicators were improved compared with those before treatment, and her mental state was slightly improved compared with that at admission, but the patient still had jaundice, hepatosplenomegaly, and occasionally mental abnormalities. At present, the outpatient follow-up was continued and symptomatic treatment was given.

Conclusion For patients with endocrine and metabolic symptoms caused by intracranial tumor after surgery or radiotherapy and chemotherapy, accompanied by unexplained neurological, mental, and organ dysfunction, the possibility of NPC should be considered. Niemann-pick cells can be detected by bone marrow aspiration for initial diagnosis. At present, the treatment of NPC is mainly symptomatic.