Haemophagocytic lymphohistiocytosis; This is a literature report.  A 60-year-old male patient received BNT162b2 (BNT162B2), as dose 1, single (Batch/Lot number: unknown) for covid-19 immunisation. The patient's relevant medical history included: "Barretts esophagus" (unspecified if ongoing); "transient ischaemic attack" (unspecified if ongoing). The patient's concomitant medications were not reported. The following information was reported: HAEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS (hospitalization, medically significant), 6 days after the suspect product(s) administration, outcome "recovered". The patient underwent the following laboratory tests and procedures: Angiotensin converting enzyme: Rheumatologic workup (negative), notes: SLE; Antibody test: Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative, notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: mixed connective tissue disorder; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Rheumatologic workup (negative), notes: Dermatomyositis/polymyositis/antisynthetase syndrome; Anti-cyclic citrullinated peptide antibody: Rheumatologic workup (negative), notes: rheumatoid arthritis; Antineutrophil cytoplasmic antibody: Rheumatologic workup (negative), notes: vasculitis; Rheumatologic workup (negative), notes: vasculitis; Antinuclear antibody: Rheumatologic workup (negative), notes: SLE; Aspergillus test: Infectious Workup (negative); Bacterial test: Infectious Workup (negative), notes: cryptococcus neoformans; Infectious Workup (negative), notes: cytomegalovirus; Infectious Workup (negative), notes: enterovirus; Infectious Workup (negative), notes: Haemophilus influenzae; Infectious Workup (negative), notes: herpes simplex  virus 1/2; Infectious Workup (negative), notes: human herpesvirus 6; Infectious Workup (negative), notes: human parechovirus; Infectious Workup (negative), notes: JC virus; Infectious Workup (negative), notes: leptospirosis, listeria; Infectious Workup (negative), notes: neisseria; Infectious Workup (negative), notes: streptococcus agalactiae; Infectious Workup (negative), notes: streptococcus pneumonia; Infectious Workup (negative), notes: varicella; Infectious Workup (negative), notes: West Nile Virus; Biopsy bone marrow: Oncological workup (negative); showed haemophagocytosis; Biopsy lymph gland: Oncological workup (negative); Blood culture: Unknown result; Blood fibrinogen: 291 mg/dl; Blood immunoglobulin G: Rheumatologic workup (negative), notes: IgG4 -related disease; Blood triglycerides: rising, notes: follow-up visits; 260; Body temperature: 38.3 Centigrade; Computerised tomogram abdomen: Oncological workup (negative); Computerised tomogram thorax: Oncological workup (negative); CSF culture: Infectious Workup (negative); Culture: Infectious Workup (negative); Epstein-Barr virus test: Infectious Workup (negative); Fibrin D dimer: unknown result; Flow cytometry: Oncological workup (negative); Haemoglobin: 88 g/dl, notes: Anaemia; HIV test: Infectious Workup (negative); Interleukin-2 receptor assay: 33 903.1 pg/mL; Babesiosis: Infectious Workup (negative); Infectious Workup (negative); Infectious Workup (negative); Infectious Workup (negative); unavailable; Infectious Workup (negative); Infectious Workup (negative); Infectious Workup (negative), notes: cytomegalovirus; Infectious Workup (negative); Mediastinal biopsy: Oncological workup (negative); Mycobacterium tuberculosis complex test: Infectious Workup (negative); Natural killer cell count: unavailable; Neutrophil count: 2.02 kiU/L; Oesophagogastroduodenoscopy: Oncological workup (negative); Parvovirus B19 test: Infectious Workup (negative); Pathology test: Oncological workup (negative); Platelet count: 43 kiU/L, notes: Thrombocytopaenia; Positron emission tomogram: Oncological workup (negative); Rheumatoid factor: Rheumatologic workup (negative), notes: rheumatoid arthritis; SARS-CoV-2 test: negative; Serum ferritin: elevated, notes: follow-up visits; Serum ferritin: 1365 ng/ml. Therapeutic measures were taken as a result of haemophagocytic lymphohistiocytosis.  No follow-up attempts are possible; information about lot/batch number cannot be obtained. No further information is expected.; Sender's Comments: As there is limited information in the case provided, the causal association between the reported event haemophagocytic lymphohistiocytosis with the suspect drug BNT162B2 cannot be excluded. The case will be reassessed once new information is available. The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to regulatory authorities, Ethics Committees, and Investigators, as appropriate.,Linked Report(s) : US-PFIZER INC-202200608920 Same drug/event and different patient