A  

Recurrent arthralgias in a young woman suggest an underlying autoimmune disorder such as systemic lupus erythematosus; immune thrombocytopenic purpura (a megakaryocytic thrombocytopenia) commonly accompanies these diseases and presents with mucocutaneous bleeding such as petechiae when platelet counts fall [Pamuk, 2023, PMID 37885267; Zainal, 2019, PMID 30788080].