LAUSR

To the Editor, Autoimmune lymphoproliferative syndrome (ALPS) is an autosomal dominant disorder of lymphocyte homeostasis wherein patients present with splenomegaly and lymphadenopathy [1]. ALPS results from defective apoptosis of T lymphocytes and accumulation of the T cell receptor α/β chainpositive and CD4 and CD8-negative double negative T (α/βDNT) cells. This leads to lymphadenopathy and splenomegaly during the early years of life. Patients with ALPS exhibit elevated levels of α/β-DNT cells in the peripheral blood and lymphoid tissues [1]. Therapy for ALPS comprises steroids and immunosuppressants to improve immune cytopenia. Sirolimus was shown to be effective in autoimmune cytopenia in a recent prospective multi-institutional trial [2]. Splenomegaly is one of the complications of ALPS, and patients with remarkable splenomegaly are forced to limit their daily activities to prevent splenic rupture. Splenectomy should be avoided in ALPS patients owing to its limited efficiency for immune cytopenia and associated high risk of severe infection [3]. However, there are no treatment guidelines for managing splenic rupture in ALPS patients. Pediatric splenic rupture is a life-threatening organ injury that requires immediate intervention in certain cases. Although the main cause of splenic rupture is strong blunt trauma, idiopathic splenic rupture or splenic rupture following minor trauma has been reported in patients with splenomegaly [4]. In such cases, understanding the underlying cause(s) is imperative to design an appropriate treatment plan. However, the exact cause of splenomegaly cannot always be determined. Here, we present the case of a patient with ALPS who was diagnosed following slight splenic injury and discuss the management and differential diagnosis of splenic rupture induced by splenomegaly. The patient was an 8-year-old Japanese girl. At 4 years of age, she developed lymphadenopathy and underwent lymph node biopsy; however, histological analysis showed no significant findings or malignancy. She had been uneventful since, but hit her stomach on the handle of her bicycle. Thereafter, she developed strong abdominal pain, vomiting, and was admitted to the Emergency Department of Japanese Red Cross Kumamoto Hospital. Abdominal contrast-enhanced computed tomography revealed massive splenomegaly and grade 2 splenic injury (Fig. 1a). Ascites was detected in Douglas fossa, suggesting bleeding from the spleen (Fig. 1b). However, she was hemodynamically stable and did not require a transfusion or vasopressor. Laboratory data showed mild anemia and thrombocytopenia and decreased haptoglobin levels, indicating autoimmune cytopenia (Supplementary Table). In addition, increased levels of serum IgG and vitamin B12 and massive splenomegaly led us to suspect ALPS. Flow cytometry of peripheral blood showed 14% α/β-DNT cells (normal < 1.5%) (Supplemental Figure A). Novel missense mutation in FAS (c.784A>T, p.Ile262Phe) was detected by Sanger Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10875-020-00809-3) contains supplementary material, which is available to authorized users.