Case report: Clinical, imaging, and genetic characteristics of type B niemann pick disease combined with segawa syndrome diagnosed via dual gene sequencing

Niemann Pick disease B (NPB) often presents with hepatosplenomegaly and lung pathological changes, but it usually does not present with central nervous system symptoms. This report presents the unique case of a 21-year-old woman with a 10-year history of hard skin and hepatosplenomegaly. Genetic sequencing revealed NPB and also suggested Segawa syndrome. Although symptomatic supportive treatments were administered in an attempt to improve muscle tone and treat the skin sclerosis, their efficacy was not satisfactory, and the patient refused further treatment. This case provides several noteworthy findings. First,although NPB and Segawa syndrome are rare, both are autosomal recessive inherited diseases that share common clinical symptoms and imaging manifestations. Second, when NPB and Segawa syndrome are highly suspected, screening for tyrosine hydroxylase (TH) and sphingomyelin phosphodiesterase-1 (SMPD1) gene mutations is critical to determine an accurate diagnosis. Finally, early diagnosis and comprehensive therapies are crucial for improving the prognosis of patients with NPB and Segawa syndrome.

whole exome sequencing revealed a variant in the SMPD1gene (chromosomal position chr11: 6415105_6415108, variant information NM: 000,543.5: c.1341-21_ 1341-18del, genetic pattern AR, homozygote, ACMG variant classification pathogenic variation) and Segawa syndrome [variant gene TH, chromosomal position chr11: 2188714, variant information NM_199,292.3: c.739G>A (p.Gly247Ser), genetic pattern AR, homozygote, ACMG variant classification pathogenic variation] (Figure 1). High-resolution chest computed tomography (CT) revealed diffuse miliary nodules distributed along the bronchial vascular tree in both lungs, with regular lung morphology and relatively uniform density. The interlobular septum exhibited slight local thickening (Figure 2). Plain radiography of the patient’s hands revealed that the bone trabeculae of both hands were slightly sparse, density was slightly reduced, the cortex was thinner, the marrow cavity was widened, and the alignment of the distal interphalangeal joints of the left index and middle fingers and the proximal interphalangeal joints of the right little finger showed swan neck-like changes (Figure 3).Abdominal ultrasonography and CT revealed enlargement of the liver and spleen (Figure 4)