Hello and welcome to HCM,
A lump on the middle of the back needs urgent attention.
A lump in an elderly needs to be investigated and a possibility of malignant or cancer needs to be ruled out.
I suggest you to consult your your primary healthcare provider for clinical assessment.
A clinical assessment is required to determine the character of the lesion.
Mid back is prone to develop
soft tissue tumors.
As you have mentioned that the lesion is hard, a bony lesion needs to be ruled out.
If the lesion appears to be bony, a X-ray of back will be required.
An aspiration cytology of the lesion needs to be done which involved introduction of a fine needle, aspiration of cellular material, staining of the cells and examination under microscope.
The microscopic examination will determine the origin of the lesion and its nature - benign or malignant.
Thanks and take care
Dr Shailja Puri