Cold agglutinin syndrome (CAS) is a rare subset of autoimmune hemolytic anemia (AIHA) and can be classified as either primary or secondary. Secondary cold agglutinin disease has been associated with both viral and bacterial pathogens with the most common bacterial pathogen being Mycoplasma pneumoniae. Legionella pneumonia is a well-known causative agent for community-acquired pneumonia that can lead to a severe disease requiring hospitalization that is rarely associated with AIHA. We highlight the importance of recognizing Legionella pneumonia as a causative pathogen for CAS.

Cold agglutinin hemolytic anemia (cAHA) is a rare autoimmune disorder characterized by the production of cold agglutinins. We present a case of secondary cAHA in a 23-year-old female with severe anemia and unexplained hemolysis. The patient exhibited findings indicative of hemolysis and a positive direct antiglobulin test (DAT) with complement alone. Additional investigations revealed incidental lung infiltrates, negative serology for infections and autoimmune diseases, and a low cold agglutinin titer. The patient showed a favorable response to doxycycline and supportive therapy, including multiple packed red blood cell transfusions. At the two-week follow-up, the patient had a stable hemoglobin level with no evidence of ongoing hemolysis. This case highlights the importance of considering secondary cAHA in patients with cold symptoms or unexplained hemolysis. Primary cAHA patients may require more aggressive treatment, including rituximab and sutilumab.

Drugs can have a wide array of effects on hematological cells, including red blood cells (RBCs), white blood cells (WBCs), and platelets. Drug-induced hemolytic anemia (DIHA) can be explained by three different pathophysiological mechanisms. We present a case of a premature neonate born at 34 weeks gestation who was admitted to the neonatal intensive care unit (NICU). He developed respiratory difficulty with mottled skin and was suspected to have bacterial sepsis due to necrotizing enterocolitis (NEC). The patient was eventually started on a broad-spectrum antibiotic, piperacillin-tazobactam. On day eight, the patient started developing jaundice and his hemoglobin level dropped from 12.1 to 8.2 mg/dL. His direct antiglobulin test (DAT) was strongly positive. The patient was suspected to have DIHA. Piperacillin-tazobactam is a commonly used antibiotic for neonatal sepsis, but its potential to cause DIHA in neonates is not well-established. Our case highlights the importance of considering piperacillin-tazobactam as an unrecognized contributor to neonatal jaundice and a potential cause of DIHA in neonates. Further research is needed to explore the extent of its involvement in this condition. Physicians should be cautious when administering this drug to neonates and be aware of the possibility of hemolysis and jaundice.

The association between malignancies and autoimmunity had been well-established. The proposed pathophysiology and causality can be bidirectional. For example, a paraneoplastic syndrome can be triggered by an underlying malignancy or vice versa, where chronic inflammation of organs affected by autoimmunity can induce malignant transformation such as the case with inflammatory bowel disease and colorectal cancer or primary sclerosing cholangitis and hepatobiliary cancer. This report presents a case of autoimmune phenomena, namely, autoimmune hemolytic anemia, pernicious anemia, and Graves disease associated with newly diagnosed breast cancer. We also highlight the postulated pathophysiologic mechanisms in an attempt to answer the question of whether the occurrence of these autoimmune phenomena in our patient is a result of the law of parsimony (Occam\'s razor), where clinical variables are pathogenically related, or the counterargument, where random events and diseases can take place simultaneously (Hickam\'s dictum).

Cold agglutinin disease (CAD) is a type of hemolytic anemia in which cold agglutinins can cause agglutination of red blood cells in cold parts of the body and hemolytic anemia. Cold agglutinin-mediated hemolytic anemia can occur in the setting of an underlying viral infection, autoimmune disorder, or lymphoid malignancy, referred to as a secondary cold agglutinin syndrome, or without one of these underlying disorders, referred to as primary CAD (also known as idiopathic CAD). We present a case of a 71-year-old female with hemolytic anemia due to primary CAD. The secondary causes of CAD, including infections, autoimmune disorders, and malignancy, were ruled out. She was successfully treated with prednisone.

Drug-induced immune hemolytic anemia is an exceedingly rare adverse drug event. Thiazide diuretics, commonly used in the treatment of primary hypertension, have been associated with this complication. In this case report, we present a 77-year-old male who developed acute hemolytic anemia two days after starting hydrochlorothiazide in the treatment of high blood pressure.

Non-steroidal anti-inflammatory drugs are widely used for pain management. Most frequently, adverse reactions affect the gastrointestinal tract and hematological side effects usually relate to the gastrointestinal manifestations. Drug-induced immune hemolytic anemia is a rare and frequently underdiagnosed complication that is associated with poor outcomes including organ failure and even death. A 76-year-old female patient was treated with intramuscular diclofenac, thiocolchicoside, and diazepam for low back pain. Five days following diclofenac exposure, the patient was admitted to the Emergency Department with complaints of asthenia, nausea, vomiting, and diarrhea. Hemolysis and a positive direct antiglobulin test were detected on laboratory testing. Further causes of hemolytic anemia were excluded and a diagnosis of diclofenac-induced immune hemolytic anemia was established. Glucocorticoid therapy initiated on admission and drug eviction led to complete recovery. Long-term follow-up showed no recurrence of anemia. Here, we present the unusual case of a successful recovery of a 76-year-old patient with diclofenac-induced immune hemolytic anemia, a rare but immediate life-threatening condition of a frequently used drug in clinical practice.

Dabigatran is an orally active direct thrombin inhibitor, initially approved by FDA for the prophylaxis of stroke and systemic embolism in the setting of non-valvular atrial fibrillation (NVAF). Major bleeding is its most common adverse event which is of great concern. However, other types of adverse events such as esophagitis, esophageal ulcer, exanthem and pustular eruptions were reported increasingly in recent years. We present a case of immune hemolytic anemia (IHA) due to dabigatran use in a 72-year-old male with NVAF. This new and rare reported type of adverse event associated with dabigatran suggests that dabigatran may be a new cause of drug-induced immune hemolytic anemia (DIIHI).