The ground glass attenuation may be an indication of Interstial Lung Disease(ILD). The cyst can be a part of this or may be because of COPD in view of past history of smoking
. ILD is a possibility since you have ankylosing spondolitis-a collagen vascular disease
. You could be having some other collagen vascular disease in which lung involvement is known. I suggest you consult a pulmonologist
and a rheumatologist
who together can look at your problem and advise you accordingly.