Mixed connective tissue disease is a rare autoimmune disease that manifest features of systemic lupus erythematous, scleroderma, and polymyositis.
What is a Mixed Connective Tissue Disease?

Puffy fingers in a patient with mixed connective tissue disease. Cutaneous manifestations of mixed connective tissue disease: study from a tertiary care hospital in eastern India.
Sen S, Sinhamahapatra P, Choudhury S, Gangopadhyay A, Bala S, Sircar G, Chatterjee G, Ghosh A - Indian journal of dermatology (2014). Not Altered. CC.