Vitamin B12 has essential roles in DNA synthesis, red blood cell development, and neurologic functions. Vitamin B12 deficiency is relatively common, particularly in people aged over 60 years. Among hematological disturbances, microangiopathic hemolytic anemia with thrombocytopenia or so-called pseudo-thrombotic microangiopathy (pseudo-TMA) is a particularly rare but significant clinical complication in patients with vitamin B12 deficiency. We herein describe a case of an elderly patient with pseudo-TMA whose lack of vitamin B12 was misdiagnosed as thrombotic thrombocytopenic purpura (TTP). The patient was admitted as a case of pancytopenia with a hemolytic picture. The initial impression was TTP versus acute promyelocytic leukemia M3. After examination of laboratory tests and bone marrow examination, we deduced that the patient had a B12 deficiency. The condition of the patient improved with B12 replacement. This report should remind physicians to widen their differential diagnoses when patients present with microangiopathic hemolysis or in patients who are not responsive to standard treatments for TTP.

Kikuchi-Fujimoto disease (KFD), also called histiocytic necrotizing lymphadenitis, is a benign self-limited disease involving lymph node enlargement with unclear causes and high fever. It was first seen in Japan and has wide array of differentials, and thus it can be confused with other causes of lymphadenitis leading to an incorrect treatment. We describe a case of a 34-year-old man with prolonged painless cervical lymphadenopathy and fever, in whom KFD, that is histiocytic necrotizing lymphadenitis, was diagnosed after the gold standard test of lymph node biopsy. Physical examination, history, and other relevant investigations were performed to rule out infectious and autoimmune causes. For management, prednisone 80mg and hydroxychloroquine were given, which lead to an uneventful full recovery. Our findings were compared to other similar studies conducted in the past. KFD is a self-limited condition that usually resolves by itself. KFD should be considered in the differential diagnosis of lymphadenopathy. An accurate diagnosis requires close collaboration between clinicians and pathologists. Early diagnosis of KFD allows reducing stress caused by alarming symptoms and avoiding unnecessary treatment.

Myeloid sarcoma, also known as granulocytic sarcoma or chloroma, is an extra-medullary accumulation of malignant myeloid blast cells, leading to a solid tumor formation. Herein, we report a rare presentation of a case with acute myeloid leukemia (AML), whose disease relapse was clinically evident as acute flaccid paraplegia with a certain sensory level. On thoracic spine magnetic resonance imaging (MRI), an epidural mass compressing the spinal cord at the level of the thoracic spine segment 4 (T4) was found. The mass histology confirmed the diagnosis of myeloid sarcoma.

Multiple autoimmune syndrome (MAS) is a condition characterized by three or more autoimmune disorders in the same individual. The development of MAS involves genetic, immunological, and infectious factors. Here we report a case of a 40-year-old man who presented with four autoimmune diseases, namely autoimmune hypothyroidism, alopecia universalis, celiac disease, and immune thrombocytopenic purpura (ITP), which leads to a diagnosis of MAS. However, the patient does not fit in any category of MAS classification. In addition to the need for continued surveillance for the development of new autoimmune disease in predisposed patients, this case report suggests an additional fourth category of the classification of MAS that includes autoimmune hypothyroidism, alopecia universalis, celiac disease, and ITP.

Inborn errors of immunity, including primary immunodeficiency disorders (PIDs), comprise a heterogeneous group of genetic conditions characterized by immune system dysfunction. One such rare PID is CD137 deficiency, which results from TNFRSF9 mutations. CD137, also known as 4-1BB, plays a pivotal role in immune system regulation and co-stimulation. This literature review explores CD137 deficiency and its implications, emphasizing its association with EBV-associated lymphoproliferative disease and potential therapeutic targets. We present the case of a 21-year-old female patient with CD137 deficiency who experienced recurrent infections, autoimmunity, and lymphoma. Genetic analysis revealed that the patient had a homozygous TNFRSF9 variant. The patient subsequently developed severe Epstein–Barr virus (EBV)-associated lymphoproliferative disease, which is one of the clinical manifestations associated with CD137 deficiency. Additionally, this review discusses similar cases in the literature and details the clinical manifestations and immune abnormalities associated with CD137 deficiency. Understanding the genetic complexity of CD137 deficiency and the immune system dysregulation it causes provides insights into potential therapeutic interventions for affected individuals. This review highlights the role of CD137 as a crucial regulator of immune homeostasis and a potential target for immunotherapy in autoimmune diseases and malignancies.