SWEETS SYNDROME WITH VASCULITIS; TRANSIENT MONOCLONAL IGA GAMMOPATHY; This spontaneous report was received from literature: A Case of Generalized Sweet's Syndrome with Vasculitis Triggered by Recent COVID-19 Vaccination. This report concerned a 54- year- old male of unspecified race and ethnicity. The objective of this study was to report a rare case of Sweet's syndrome(SS) with vasculitis and transient IgA monoclonal gammopathy triggered by a Janssen Ad26.COV2.S vaccine. The patient's height, and weight were not reported. The patient had no significant past medical history. The patient had no fevers, chills, night sweats, or  weight loss. The patient received COVID-19 vaccine Ad26.COV2.S (suspension for injection, route of admin, and batch number were not reported) dose,  9 days prior to onset ( vaccination date was  not reported), 1 dose total administered for prophylactic vaccination. The batch number was not received and has been requested. No concomitant medications were reported. On an unspecified date (9 days post vaccination), the patient presented to Emergency department with significant pain, tongue swelling and ulceration. Upon physical examination the patient had an erythematous, fissured tongue with confluent erosions and dozens of firm, blanching and erythematous and papulonecrotic nodules on the extremities and trunk. The scrotum had flesh-colored and erythematous plaques. The plantar aspects of the feet had erythematous and targetoid macules. The patient's lesions progressed over one week, and he developed new eroded and crusted plaques on the scalp, trunk, and extremities. The genital and plantar foot lesions became more targetoid in appearance which is diagnosed has Sweet's syndrome with vasculitis and transient monoclonal IgA gammopathy. The patient was treated with a 10-day course of steroids. Laboratory data (dates unspecified) included: Erythrocyte sedimentation rate (NR: not provided) 29 mL/h, leukocyte count (NR: not provided) 10.84 10*3/uL, neutrophil count (NR: not provided) 90 %, Acid fast bacillus culture (NR: not provided) unremarkable, Antineutrophil cytoplasmic antibody (NR: not provided) negative, Antinuclear antibody (NR: not provided) negative (units unspecified), C-reactive protein (NR: not provided) 19.6 mg/L, COVID-19 PCR test (NR: not provided) negative, COVID-19 serology test (NR: not provided) negative, Computerized tomography of the chest, abdomen and pelvis (NR: not provided) unremarkable, Tissue specimen culture  (NR: not provided) unremarkable, Three 3-millimeter punch biopsies (NR: not provided) not reported; Direct immunofluorescence (DIF) (NR: not provided) unremarkable, Hematoxylin-eosin staining (NR: not provided)  showed dense interstitial and perivascular neutrophilic infiltrate with leukocytoclasia and focal fibrin deposition in blood vessel walls, and serum protein electrophoresis (NR: not provided) positive abnormal monoclonal IgA lambda. Repeat serum protein electrophoresis after 10 weeks from onset showed resolution of monoclonal IgA lambda. The action taken with COVID-19 vaccine Ad26.COV2. S was not applicable. The patient was recovering from Sweet's syndrome with vasculitis, and transient monoclonal IgA gammopathy was resolved. The authors concluded that postulate immune response similar to COVID-19 infection was experienced in the recently vaccinated patient. Following treatment, the IgA monoclonal gammopathy resolved, highlighting the transient nature of immunoglobulin response and subsequent vasculitis,  it is imperative for physicians to be aware of these significant yet transient side effects and to understand that they are not a contraindication for vaccination against SARS-CoV-2. This report was serious (Other Medically Important Condition).; Sender's Comments: V0: This spontaneous case received from literature concerned a 54-year-old man of unspecified race and ethnicity who experienced acute febrile neutrophilic dermatosis, Sweet's syndrome (SS) and monoclonal IgA gammopathy,  9 days  after Janssen COVID-19 vaccine administration.  The patient  didn't have any significant past medical history. Concomitant medications were not reported.  He presented to Emergency Department with significant pain, tongue swelling and ulceration, but no fever, chills, night sweats or weight loss. Physical exam revealed: fissured tongue with confluent erosions and dozens of firm, blanching, erythematous and papulonecrotic nodules on the extremities and trunk, erythematous plaques on scrotum, and plantar feet with targetoid macules.  Lab work and diagnostics included: ESR: 29 mL/h, leukocyte count 10.84 10*3/uL, neutrophil count: 90 %, CRP: 19.6 mg/L,  protein electrophoresis positive for abnormal monoclonal IgA lambda. Antineutrophil cytoplasmic antibody and antinuclear antibody were negative. Result of punch biopsy was not reported. COVID-19 PCR and serology, were negative.  A CT chest, abdomen and pelvis, tissue culture, tissue direct immunofluorescence and acid fast bacillus culture were unremarkable. Hematoxylin-eosin staining showed dense interstitial and perivascular neutrophilic infiltrate with leukocytoclasia and focal fibrin deposition in blood vessel wall.  He was diagnosed with SS, vasculitis with transient monoclonal IgA gammopathy. He was treated with steroids for 10 days and is recovering from SS and was recovered from monoclonal gammopathy. Although, the occurrence of SS  and transient monoclonal IgA gammopathy could represent background incidence of such events in the general population, considering plausible temporal relationship and a lack of alternative explanation, the  triggering role of Janssen COVID-19 vaccine  cannot be excluded and the events are assessed to have  indeterminate causal association to vaccination.