Ct scan shows 1mm calcified granuloma in lower left lobe (lower thorax). could be from an old back muscle inflammation/injury?. never smoked or had tb/lung infections.

Not from injury: A pulmonary granuloma is not due to a back injury. The good news is that it is not usually anything to worry about if it is stable.

Further evaluation: needed to find the nature of that ' 1mm of calcified granuloma ' are sure of the size , could be due to several other causes besides what you mentioned , cryptococous , sarcoidosis histoplasmosis etc , speak to your doctor , your old back muscle inflammation will not cause .

Insignificant: Calcified granulomas are incidental findings often discovered on imaging exams. It is likely from an old infection or other insult, usually one of which you are not usually aware.