is the numbness at one side of the ring finger and both sides of the little finger?
try clenching your fist and opening your fingers one by one .are you able to do it for your ring and little finger?
where exactly is the lump in the hand,on the side of the palm or on the skin side?
sorry,had problems with the net.
all right,now tell me,is the lump fixed to the skin?can you pinch the skin over the lump?
its probably a ganglion then.
this is a benign condition,but because you seem to have pressure effects,please consult a surgeon and get it removed,its a minor surgical procedure.
yes,the lesion is causing pressure on the ulnar nerve .You have typical symptoms of ulnar nerve palsy.
please do get it removed before the nerve gets damaged.