Padget's Sarcoma

Introduction

The risk of malignant change in Padget's disease is of the order of 1/100. In the older population up to 40% of such tumours present in the pelvis. Padget's disease associated with osteosarcoma more frequent among males, 1.58:1.

Investigations

Bone turnover can be assessed with blood tests. High alkaline phosphatase levels suggest a worse prognosis because of the existence of a more aggressive and bulky tumour.

Imaging is critical in staging the condition:-

MRI evaluation of the bone is performed to assess extent of disease and to identify skip metastases.
CT scan of the thorax is performed to evaluate lung metastases.
Bone scans are performed to evaluate involvement of other bony sites.

Biopsy is diagnostic, but should usually be undertaken in a specialist bone tumour centre. Biopsy should be an incisional one or utilize a core needle technique. Fine needle aspiration is not an acceptable biopsy technique since it provides too little sample for accurate diagnosis. Core needle biopsies for malignant bone tumours yield diagnostic accuracy that ranges from 74-88%.

The site of incisional biopsy is important, as that site ultimately will need to be resected en bloc following diagnosis. An incisional type biopsy provides the largest amount of tissue and has the greatest likelihood of diagnostic success, approximately 96%.

Surgical Treatment

Surgical resection requires a wide excision to ensure complete resection of disease, this includes complete removal of the tumour with previously placed biopsy tract, drain, or potentially contaminated tissues.

In determining the extent of surgery the optimal oncological outcome takes priority over functional outcomes. Amputation or dysarticulation may be required, although more conservative management that allows limb salvage and reconstruction must be considered.

Chemotherapy (Please note this regime may be out of date!)

Neoadjuvant or induction chemotherapy generally administered for a period of 10 weeks prior to surgical resection. Following surgical resection, and wound healing maintenance chemotherapy is given for 29 weeks.

Standard treatment consists of cisplatin, doxorubicin and high-dose methotrexate resulting in relapse free survival rates of up to 60%-70%.

For patients with recurrent disease ifosfamide associated with 30-40% response rates.