Severe RAS-Associated Lymphoproliferative Disease Case with Increasing αß Double-Negative T Cells with Atypical Features.

Autoimmune lymphoproliferative syndrome (ALPS) is a disease of lymphocyte homeostasis caused by FAS-mediated apoptotic pathway dysfunction and is characterized by non-malignant lymphoproliferation with an increased number of TCRαß+CD4-CD8- double-negative T cells (αßDNTs). Conversely, RAS-associated leukoproliferative disease (RALD), which is caused by gain-of-functional somatic variants in KRAS or NRAS, is considered a group of diseases with a similar course. Herein, we present a 7-year-old Japanese female of RALD harboring NRAS variant that aggressively progressed to juvenile myelomonocytic leukemia (JMML) with increased αßDNTs. She eventually underwent hematopoietic cell transplantation due to acute respiratory distress which was caused by pulmonary infiltration of JMML blasts. In general, αßDNTs have been remarkably increased in ALPS; however, FAS pathway gene abnormalities were not observed in this case. This case with RALD had repeated shock/pre-shock episodes as the condition progressed. This shock was thought to be caused by the presence of a high number of αßDNTs. The αßDNTs observed in this case revealed high CCR4, CCR6, and CD45RO expressions, which were similar to Th17. These increased Th17-like αßDNTs have triggered the inflammation, resulting in the pathogenesis of shock, because Th17 secretes pro-inflammatory cytokines such as interleukin (IL)-17A and granulocyte-macrophage colony-stimulating factor. The presence of IL-17A-secreting αßDNTs has been reported in systemic lupus erythematosus (SLE) and Sjögren's syndrome. The present case is complicated with SLE, suggesting the involvement of Th17-like αßDNTs in the disease pathogenesis. Examining the characteristics of αßDNTs in RALD, JMML, and ALPS may reveal the pathologies in these cases.

Difficulties of diagnosing idiopathic hypertrophic pachymeningitis in children: Case report and literature review.

Hypertrophic pachymeningitis (HP) is a rare inflammatory disorder characterised by local or diffuse thickening of the cranial and spinal dura mater. HP occurs owing to idiopathic or secondary causes, including autoimmune disease, infection, and trauma. HP has mainly been reported in adults, with few reported cases in children. We encountered an 11-year-old boy with idiopathic HP who presented with chronic inflammation and daily occipital headache. Gadolinium (Gd)-enhanced magnetic resonance imaging (MRI) helped us to diagnose him with HP. He was successfully treated with corticosteroids and azathioprine with no recurrence. We also conducted a literature review of childhood-onset HP and found only 16 cases, including our patient. Seven patients had idiopathic HP, and the remaining nine had secondary HP, including two with rheumatic disease. The most common clinical symptoms were headache (68.8%) and cranial nerve-related symptoms (68.8%). Inflammatory laboratory markers were elevated in 60% of patients with available data. Fifteen cases were diagnosed using Gd-enhanced MRI. The main initial treatment was steroids and/or immunosuppressants, to which 87.5% of patients responded. However, two patients with HP associated with trauma and neuroblastoma (12.5%) died, and seven patients (43.8%) had left cranial nerve-related sequelae. As the prognosis for childhood HP is poor, early diagnosis and treatment are essential. Children with headache, cranial nerve symptoms, and elevated inflammatory marker levels should be suspected of having HP and Gd-enhanced MRI should be considered.