Significant post lymphadenopathy flare that was extensive to the entire body; Jynneos administrated intradermally; Case reference number US-BN-2022-004069 is a spontaneous case report initially received on 11-Oct-22 from a physician via agency (reference number: USBAV22-1684) and concerns a male patient of unspecified age.  The patient's current medical condition included chronic lymphocytic leukaemia (CLL) (in remission type status).  The patient's concomitant medication details were not provided.  On an unspecified date, the patient was vaccinated with Jynneos vaccine (smallpox and monkeypox vaccine, live, nonreplicating; batch number: unknown), at an unknown dose, administrated intradermally, for monkeypox prophylaxis (explicitly coded as 'intradermal injection').  On an unspecified date, an unknown amount of time after the vaccination, the patient experienced significant lymphadenopathy flare that was extensive to the entire body.   At the time of this report, the outcome of 'lymphadenopathy' was unknown.  The reporter assessed the event as non-serious and possibly related to Jynneos.  Additional information received from Bavarian Nordic on 12-Oct-2022 included local BN case ID.; Reporter's Comments: A male patient of unspecified age experienced significant lymphadenopathy flare that was extensive to the entire body, unknown time after he was vaccinated with Jynneos (at unknown dose, for monkeypox prophylaxis), administered intradermally (considered as monkeypox prophylaxis). Lymphadenopathy is listed according to agency 1 however unexpected according to agency 2 for Jynneos while injection is considered listed per company convention. The outcome was unknown. The patient's current medical condition included chronic lymphocytic leukaemia (CLL) (in remission type status) while concomitant medication details were not provided. Lymphadenopathy is conservatively assessed as related due to known product safety profile, lack of alternative explanation and since contributory role of the suspect product cannot be fully excluded at this point.  According to the current literature the most common abnormal finding on physical examination of the patient with CLL is lymphadenopathy, present in 50 to 90 percent of patients among various series which confounds causality assessment in this case. Injection is assessed as not related to suspect product but to human factor. The case is non-serious.; Sender's Comments: A male patient of unspecified age experienced significant lymphadenopathy flare that was extensive to the entire body, unknown time after he was vaccinated with Jynneos (at unknown dose, for monkeypox prophylaxis), administered intradermally (considered as monkeypox prophylaxis). Lymphadenopathy is listed according to agency 1 however unexpected according to agency 2 for Jynneos while injection is considered listed per company convention. The outcome was unknown. The patient's current medical condition included chronic lymphocytic leukaemia (CLL) (in remission type status) while concomitant medication details were not provided. Lymphadenopathy is conservatively assessed as related due to known product safety profile, lack of alternative explanation and since contributory role of the suspect product cannot be fully excluded at this point.  According to the current literature the most common abnormal finding on physical examination of the patient with CLL is lymphadenopathy, present in 50 to 90 percent of patients among various series which confounds causality assessment in this case. Injection is assessed as not related to suspect product but to human factor. The case is non-serious.