Purpose To explore the clinicopathological and molecular genetic features of phytosterolemia(PTSL)with necrobiotic xanthogranuloma.Methods 4 cases of PTSL with necrobiotic xanthogranuloma as the primary mani-festation were reviewed.Gene mutations were detected by whole-exome sequencing and screened and verified by Sanger sequencing.The clinical manifestations,laboratory tests,genetic testing results,treatment and prognoses of the pa-tients were analyzed.Results All 4 patients developed subcutaneous masses on the face over a period of 3-13 years.Case 4 showed weakness of both lower limbs and an intracranial mass on MRI.Blood smear analysis revealed that the patients had platelets of varying sizes and were generally large,with increased stomatocytes.Total cholesterol(6.9-11.36 mmol/L)and low-density lipoprotein(4.45-7.08 mmol/L)were elevated in 4 patients.Genetic analysis re-vealed that cases 2 and 4 carried heterozygous mutations in the ABCG5 gene,and case 3 had a homozygous mutation in the ABCG8 gene.Conclusion Thrombocytopenia,stomatocytosis and splenomegaly are the special clinical manifesta-tions of patients with PTSL,and necrobiotic xanthogranuloma may be one of the late manifestations of the disease.Early genetic testing plays a critical role in the timely diagnosis and management of PTSL.

Purpose To explore the clinicopathological and molecular genetic features of phytosterolemia(PTSL)with necrobiotic xanthogranuloma.Methods 4 cases of PTSL with necrobiotic xanthogranuloma as the primary mani-festation were reviewed.Gene mutations were detected by whole-exome sequencing and screened and verified by Sanger sequencing.The clinical manifestations,laboratory tests,genetic testing results,treatment and prognoses of the pa-tients were analyzed.Results All 4 patients developed subcutaneous masses on the face over a period of 3-13 years.Case 4 showed weakness of both lower limbs and an intracranial mass on MRI.Blood smear analysis revealed that the patients had platelets of varying sizes and were generally large,with increased stomatocytes.Total cholesterol(6.9-11.36 mmol/L)and low-density lipoprotein(4.45-7.08 mmol/L)were elevated in 4 patients.Genetic analysis re-vealed that cases 2 and 4 carried heterozygous mutations in the ABCG5 gene,and case 3 had a homozygous mutation in the ABCG8 gene.Conclusion Thrombocytopenia,stomatocytosis and splenomegaly are the special clinical manifesta-tions of patients with PTSL,and necrobiotic xanthogranuloma may be one of the late manifestations of the disease.Early genetic testing plays a critical role in the timely diagnosis and management of PTSL.