Xanthogranulomatous cholecystitis is a rare idiopathic benign chronic inflammatory condition with a locally aggressive spread. Its clinical and radiological manifestation are variable and unpredictable. While it shares similarities with gallbladder cancer, Xanthogranulomatous cholecystitis does not necessitate aggressive surgical treatment. However, the considerable challenge to reach a preoperative diagnosis underscores the need for an aggressive surgical approach. Adding to this challenge, an extremely elevated CA19-9 is no longer a distinguishing factor.

Keywords:Xanthogranulomatous cholecystitis; CA19-9 Antigen.

Over 160 cases of subacute thyroiditis (SAT) following COVID-19 vaccination or infection have been reported in the literature. Roughly one-half were attributed to either the first or second dose of the COVID-19 vaccine. We report a rare case of SAT in a 47-year-old male patient with a history of clear cell renal cell carcinoma and advanced chronic kidney disease, among other comorbidities, excluding thyroid disease. After he received the third dose of the Pfizer mRNA vaccine, a deranged thyroid profile was accidentally discovered. His SAT remained asymptomatic and normalized in about six months without treatment. SAT post-COVID vaccination is a self-limiting and rare condition that should be considered in the differential diagnosis of silent thyroiditis.

Keywords:Subacute Thyroiditis; mRNA Vaccines; COVID-19; Pfizer-BioNTech COVID-19 Vaccine; ASIA Syndrome; Oman.