Hi there El Rancho.
From your History & clinical description it does not appear that you have any major worries or anything to be concerned about vis-a-vis major ailments that could be an impediment to your posting.
Having said that, an MRI is usually conclusive & will give you a clearer picture including that concerning the soft tissue
swelling you describe. Arthritis
is a very loose diagnosis especially after an MRI assessment.
I suggest you get onto the premier 'ask-a-specialist' portal on this site & upload a clear digital image of your particular swelling issue on your back & we will then be able to provide a clearer picture.
Given the current status, if one were to hazzard a guess, then i would think a sebaceous cyst
or a lipoma
are most likely to be the diagnoses & all are benign lesions & easily excised with minimal fuss in a day-care setting.
Good luck & wish you a safe assignment. Cheers!
Dr Praveen Rodrigues MD