Age: 71.0
Sex: M
Vaccine: FLU3, FLUX, FLUX, FLUX, FLUX
Symptoms: Gene mutation identification test negative, Hyperchromasia, Immunohistochemistry, Light chain analysis normal, Lymphocytic infiltration
Clinical narrative: This medically confirmed literature report (initial receipt 23-Jun-2015) concerns a 71 year-old male patient who had no significant medical history. On an unspecified date, the patient received influenza vaccine (Influenza virus vaccine, manufacturer and batch number not provided) on the left arm. On an unspecified date, 7 days following the influenza vaccination, the patient developed a 5.0cm non-tender, erythematous, and scaling plaque with an indurated border on the left upper arm. The lesion appeared at the site of an influenza vaccination. The patient denied systemic symptoms and any such reaction with previous vaccinations. The initial clinical suspicion was that of an injection site hypersensitivity reaction.  A punch biopsy was performed, and a topical high-potency steroid, diflorasone diacetate 0.05%, was prescribed. The biopsy found an atypical dense lymphoid infiltrate in the papillary and reticular dermis. A grenz zone was present. The infiltrate shows prominent perivascular distribution. The individual lymphocytes had hyperchromatic nuclei with irregular nuclear contour and nucleoli. Crush artefact was present at the periphery of the biopsy section. Immunohistochemical profiling found the lesion to be diffusely CD4 and CD56. Most of the lesional cells were also CD123 and TdT. Repeat CD123 staining found more intense and diffuse positivity. Admixed were rare CD79 B cells. Tests for myeloperoxidase, CD34, MUM1, PAX5, CD3, CD10, CD21, kappa, and lambda were negative. Epstein Barr virus in situ hybridization results were also negative. In addition to these markers, an outside hospital found that our lesion was TCL1 and CD117 and muramidase negative. After histologic and immunoprofiling of CD4, CD56, TCL1, and CD123, a diagnosis of blastic plasmacytoid dendritic neoplasm (BPDN) was rendered. Differential diagnosis included extramedullary myeloid sarcoma and an acute leukemia with ambiguous lineage. Absence of myeloperoxidase excluded myeloid sarcoma, and absence of CD34, myeloperoxidase, CD117, and muramidase ruled out acute leukemia. This diagnosis was confirmed by a senior hematopathologist and at major cancer centre. At the 2-week follow up, the patient reported that the entire lesion had resolved with topical steroid treatment. Despite the lack of clinical evidence of disease, radiation therapy was delivered at the site. At the time of this report, bone marrow and blood involvement were not found and leukemia was excluded, but watchful follow-up was necessary. The outcome was recovered. Follow-up (15-Sep-2015): The patient was being monitored by the heamatology-oncology team and remained baseline. The patient did not show disease progression. The influenza vaccine batch number was not available. Reporter's Comments: The reporter stated that this was an unusual case of BPDN occurring at an influenza vaccination site. The atypical presentation and behaviour raises the question if the lesion was indeed a distinct presentation of BPDN that carries a good prognosis or was a BPDN-like reaction to the vaccination. Sender's Comments: Seriousness: Serious. Medically significant. Listedness: Unlisted. Brand of vaccine not specified. Assessment according to the CCSI for CSL Inactivated Influenza Virus Vaccine and the Afluria Product Information, all events are unlisted except injection site erythema and induration which are listed. Causality: Possible. Time to onset 1 was week following vaccination.  BPDN was confirmed by histopathological examination. As per the authors, this was the 1st reported occurrence of BPDN or a BPDN-like reaction occurring at the vaccination site.  The case was atypical due to regression with topical high potency steroid. Causally related due to temporal association. Company comment (17-Sep-2015): No change in assessment.