Pyoderma gangrenosum after third dose of the Moderna Covid-19 vaccine, 1 pimple onright hip and two pimples on left hip; This spontaneous case was reported by a patient and describes the occurrence of PYODERMA GANGRENOSUM (Pyoderma gangrenosum after third dose of the Moderna Covid-19 vaccine, 1 pimple onright hip and two pimples on left hip) in a 72-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 049F21A, 032L20A and 011A21A) for COVID-19 vaccination.     The patient's past medical history included Ulcerative colitis (The patient had ulcerative colitis years ago.) and Colectomy (The patient had colon removed in 2001 to treat the ulcerative colitis.) in 2001. Concurrent medical conditions included Pyoderma gangrenosum (The patient did develop pyoderma gangrenosum after having colon removed. The patient also had two other episodes of pyoderma gangrenosum since 2001.) since 2001 and Immunocompromised (currently a patient at the Clinic.). Concomitant products included INFLUENZA VACCINE (FLU) for an unknown indication.   On 28-Jan-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 25-Feb-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 18-Aug-2021, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. In August 2021, the patient experienced PYODERMA GANGRENOSUM (Pyoderma gangrenosum after third dose of the Moderna Covid-19 vaccine, 1 pimple onright hip and two pimples on left hip) (seriousness criterion medically significant). At the time of the report, PYODERMA GANGRENOSUM (Pyoderma gangrenosum after third dose of the Moderna Covid-19 vaccine, 1 pimple onright hip and two pimples on left hip) outcome was unknown.        The patient received first and second dose on the right arm shoulder deltoid muscle. The patient reports no adverse reactions after first and second dose. The patient received third full dose on right arm. The patient describes pyoderma gangrenosum as a pimple which expands and grows and starts eating skin. This condition was usually associated with autoimmune disorders. The patient was due for the booster dose. The patient said that he was immunocompromised due to the medications.  No treatment drug was reported.  Company comment: This is a spontaneous case concerning a 72-year old male with relevant medical history of pyoderma gangrenosum, ulcerative colitis and Immunocompromised, who experienced the serious (medically significant) unexpected event of pyoderma gangrenosum after receiving third dose of mRNA-1273. No treatment information was provided. At the time of the report, outcome for the event of pyoderma gangrenosum was unknown. The medical history of pyoderma gangrenosum, ulcerative colitis, and Immunocompromised remains a confounder. The benefit-risk relationship of the mRNA-1273 vaccine is not affected by this report.   Reporter did not allow further contact; Sender's Comments: This is a spontaneous case concerning a 72-year old male with relevant medical history of pyoderma gangrenosum, ulcerative colitis and Immunocompromised, who experienced the serious (medically significant) unexpected event of pyoderma gangrenosum after receiving third dose of mRNA-1273. No treatment information was provided. At the time of the report, outcome for the event of pyoderma gangrenosum was unknown. The medical history of pyoderma gangrenosum, ulcerative colitis, and Immunocompromised remains a confounder. The benefit-risk relationship of the mRNA-1273 vaccine is not affected by this report.