<s>[INST] I have a mass between my 8th and 9th rib. It began in 10/09 the size of a pea but was not painful. By 10/2011 it was the size of a marble and vaguely painful constantly. The general surgeon I saw wanted to biopsy my rib. I underwent a robotic hysterectomy 11/2011. The OB surgeon ruled out cyst, polyp or hernia at the location. Subsequent CT showed mass and thoracic surgeon ordered a ultrasound. The ultrasound shows ossification of the 8th and 9th rib with a palpable mass between these ribs. The mass is hard (bony), protrudes and shaped like an egg. Pain is constant and sometimes throbbing and sharp. What is this?? I'm afraid it is an osteochondroma or soft tissue cancer. The thoracic surgeon dismissed me and told me to take an anti-inflammatory. [/INST] Your concern is very valid as the description that you have given is that of a slow growing tumor. It does not seem to be malignant as of now based on the long history and slow growth. However, even benign tumors can undergo malignant conversion if left untreated. The best way to ascertain this would be to undergo a biopsy from the lesion. This can be done easily on out patient basis with a thick bore needle under local anesthesia. The biopsy report will conclusively state the nature of the lesion and you can take it from there. </s>