Henoch Shonlein purpura; This is a literature case initially received on 27-Jul-2020, concerning a 4-year-old, female patient.   This report described the case of a 4-year-old girl with the unusual presentation of HSP (Henoch-Schönlein Purpura) with lumbosacral spine swelling and refusal to walk.   The patient's parents denied any trauma, insect bites, changes in behaviour, appetite, activity or recent fevers for patient. They also denied any new exposures, dietary changes, or contributory travel or family history. The patient's concomitant medications were not reported.    On an unspecified date, the patient was administered INN Flu Vaccine Seasonal [influenza virus vaccine polyvalent; dose, route of administration, anatomical location, batch number and expiry date not reported] for an unknown indication.   On an unknown date, 72 hours after influenza vaccination, the patient had rhinorrhoea (without any other upper respiratory symptoms or sore throat) and mild abdominal pain.   On the next day, the patient had a transient headache, which spontaneously subsided.   On an unknown date, two days later, the patient complained of transient, bilateral wrist, ankle and shin pain, and later that evening she developed a rash on the bilateral lower extremities and right ankle swelling. The patient's mother described the rash as initially starting as small red dots that coalesced by the next morning. Ibuprofen was given to the patient without improvement.   On an unknown date, the morning prior to presenting to the emergency department she started to complain of pain isolated to the lower back and right ankle and had a small area of painful swelling in the lumbosacral area, which made ambulation painful.  On an unknown date, the patient presented to the emergency department with a 2-day history of worsening rash and inability to walk. Upon examination in the emergency department the patient's vital signs were normal with a blood pressure of 100/60 mm Hg (50th-90th percentile for age). The patient laid in bed comfortably and was alert and oriented. There was a petechial rash extending from both proximal thighs to the dorsi of both feet. Nonpalpable purpura and nonpitting edema were noted on the right lateral malleolus, which was tender to palpation and had limited range of motion in all directions secondary to pain. A nonpitting edematous patch approximately 3 x 2 cm was also noted in the lumbosacral area that was tender to palpation without overriding erythema or induration. Otherwise, the patient's physical and neurologic examination were normal.   Laboratory investigations included a urinalysis, complete metabolic panel and coagulation panel (prothrombin time / partial thromboplastin time / international normalized ratio) which were negative. The complete blood count was normal except for an elevated white blood cell count of 17,580/µL (reference range, 4,800- 10,800 µL) and an elevated platelet count of 692,000 µL. (reference range 130,000- 400,000 µL). Inflammatory markers were slightly elevated, with the C-reactive protein level being 0.7 mg/dL. (reference range, 0.0-0.4 mg/dL) and the erythrocyte sedimentation rate being 25 mm/h (reference range, 0-20 mm/h). An x-ray of the right ankle showed isolated soft tissue swelling at the lateral malleolus.   On an unknown date, the patient was admitted to hospital.  After admission to the pediatric floor magnetic resonance imaging of the lumbosacral spine was performed, which showed mild posterior subcutaneous soft tissue swelling. Additional laboratory studies were performed including C3, C4 and IgA levels, all of which were normal. Anti-streptolysin 0 titers and anti-DNAase B titers were not drawn.   The patient's pain and immobility remitted within the next 24 hours, as did the petechiae, purpura and edema of her right ankle and lower back. No corticosteroids were given.   On an unknown date, five weeks later, the complete blood count, comprehensive metabolic panel, and urinalysis were repeated, all of which were normal, and the patient was recovered from the event of Henoch Shonlein purpura. There had been no recurrences to date.   The event of Henoch Shonlein purpura was assessed as serious due to hospitalisation and medical significance, per company.    The reporter did not provide causality assessment.  Company comment: A 4-year-old female patient was administered the suspect vaccine, INN Flu Vaccine Seasonal. The patient developed unusual presentation of HSP (Henoch-Schönlein Purpura), starting with rhinorrhoea and mild abdominal pain, 72 hours after influenza vaccination. Chronology is plausible. Although the aetiology of Henoch-Schönlein purpura (HSP) remains unclear, influenza vaccinations have been implicated as possible triggers for HSP. The patient had no medical history of immunologically mediated diseases. However, causal role of the suspect vaccine cannot be excluded and is assessed as unlikely related. (defaults to "related" in the safety database for reporting purposes; Sender's Comments: A 4-year-old female patient was administered the suspect vaccine, INN Flu Vaccine Seasonal. The patient developed unusual presentation of HSP (Henoch-Schönlein Purpura), starting with rhinorrhoea and mild abdominal pain, 72 hours after influenza vaccination. Chronology is plausible. Although the aetiology of Henoch-Schönlein purpura (HSP) remains unclear, influenza vaccinations have been implicated as possible triggers for HSP. The patient had no medical history of immunologically mediated diseases. However, causal role of the suspect vaccine cannot be excluded and is assessed as unlikely related. (defaults to "related" in the safety database for reporting purposes