ABSTRACT Acquired Hemophagocytic Lymphohistiocytosis is a rare and deadly syndrome resulting from an overactive immune system, with uncontrolled activation of macrophages and lymphocytes, hypercytokinemia, and systemic inflammatory response. A 75-year-old male presented with typical anginal pain and was diagnosed with the acute coronary syndrome, which required a percutaneous transluminal coronary angioplasty. Instead of resolving the symptoms, the patient began to exhibit pyrexia and worsening altered sensorium with progressing renal failure, anemia, thrombocytopenia and respiratory failure. This constellation of symptoms caused the patient to require mechanical ventilation and hemodialysis. Upon laboratory analysis, hyperferritinemia provided an indication to the diagnosis of acquired hemophagocytic lymphohistiocytosis. After the initiation of dexamethasone, the patient made a significant recovery and was discharged from the hospital.

ABSTRACT Erdheim-Chester disease is a rare non-Langerhans cell histiocytosis (LCH) that affects different body systems. It was recently recognized as a neoplastic disorder after identifying an activating mutation of the MAPK pathway. Neurological presentations of ECD are rare. We present a case of a 35-year-old male who presented to the emergency department with neck pain, headache and vomiting for 2 months; MRI showed multiple heterogeneous intracranial masses. Neurosurgery performed a suboccipital craniotomy, partially resected the cerebellar mass, and placed a parietal to frontal shunt catheter. Biopsy results from the cerebellar mass demonstrated cerebellar tissue involved by a diffuse proliferation of foamy histiocytes and spindle cells admixed with prominent lymphoplasmacytic infiltrate and positive for CD68, CD163, Factor XIIIa and Fascin. PET scan showed hypermetabolic uptake within the medullary portions of the diffuse abnormal lesions of the distal femurs, tibias, and fibulas, and cardiac MRI was nonsignificant. The patient was started on vemurafenib and continued to show improvement in a 3-month outpatient follow-up.