Italian Doctors Warn That Pfizer’s COVID-19 Vaccines Can Cause Onset of Familial Hemophagocytic Lymphohistiocytosis
Nikhil Prasad Fact checked by:Thailand Medical News Team Nov 26, 2025 46 minutes ago
Medical News: A Rare Neurological Case That Surprised Doctors
Researchers from Fondazione Policlinico Universitario A Gemelli IRCCS in Rome, IRCCS Ospedale Pediatrico Bambino Gesù, and Università Cattolica del Sacro Cuore have documented a striking adult case of familial hemophagocytic lymphohistiocytosis (HLH) that began with neurological symptoms soon after a Pfizer COVID19 vaccination. This
Medical News report shows how early warning signs resembled more common neuroinflammatory diseases, causing critical delays in identifying the true underlying disorder.
A rare adult case of familial HLH first appeared with neurological symptoms soon
after a COVID-19 vaccination
What Familial Hemophagocytic Lymphohistiocytosis (HLH) Is
Familial HLH is a rare but severe inherited immune disorder in which the immune system becomes dangerously overactive. Instead of turning off after fighting infection, certain white blood cells remain activated and begin damaging the body’s own tissues. These cells attack blood cells such as red cells, platelets, and neutrophils while causing intense inflammation across organs like the liver, spleen, and bone marrow.
In familial cases, genetic defects disrupt how immune cells control their responses, and although the disease often appears in infancy or childhood, some individuals remain symptom free until a trigger exposes the hidden vulnerability.
Symptoms commonly include persistent fever, enlarged organs, rashes, swollen lymph nodes, low blood cell counts, and sometimes neurological issues such as seizures or difficulty walking. HLH is life threatening without rapid diagnosis, and in inherited forms, bone marrow transplantation is often the only curative option.
Neurological Decline After Vaccination
In this documented case report, the patient, a previously healthy 46-year-old man, developed balance problems, gait ataxia and diplopia three weeks after his second Pfizer vaccine dose. MRI scans revealed multiple white matter lesions that looked identical to acute disseminated encephalomyelitis. Steroids briefly helped, but the disease returned repeatedly, producing mass like brain lesions, spinal cord inflammation, and progressive disability that resisted powerful immunosuppressive treatments.
HLH Finally Revealed Through Systemic Symptoms
After more than two years, the condition shifted into full systemic HLH. The patient developed high fever, elevated inflammatory markers, cytopenias and splenomegaly. Bone marrow testing showed hemophagocytosis, confirming HLH. Genetic sequencing identified two homozygous PRF1 mutations, including one pathogenic variant, proving that the man had familial type 2 HLH rarely seen at this age.
Transplant Response and Final Outcome
The patient underwent a matched unrelated donor stem cell transplant. Brain and spinal lesions improved significantly afterward. But months later he deve
loped severe infectious complications following SARS-CoV-2 infection and passed away, with no evidence of HLH relapse at the time of death.
Conclusions
This case shows how familial HLH can hide for decades and suddenly appear after a trigger, creating confusing neurological symptoms long before systemic signs emerge. It emphasizes the need for genetic testing in unexplained relapsing neuroinflammation and highlights that early identification of HLH can be lifesaving, even in adults.
The study findings were published in the peer reviewed journal: Diagnostics.
https://www.mdpi.com/2075-4418/15/23/3000
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A rare adult case of familial HLH first appeared with neurological symptoms soon after a COVID-19 vaccination.
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