Sacrococcygeal chordoma: Increased (99m)Tc methylene diphosphonate uptake on single photon emission computed tomography/computed tomography bone scintigraphy.

Chordoma is a malignant tumor arising from the remnants of the notochord, and is the most frequent primitive tumor of the sacrum. While most sacral tumors show increased concentration of bone-seeking radiopharmaceuticals, chordomas usually exhibit decreased uptake. The authors present an image of a sacrococcygeal chordoma with osteolysis and increased uptake of 99mTc methylene diphosphonate on planar and single photon emission computed tomography/computed tomography bone scintigraphy.

INTRODUCTION

Chordoma is a malignant tumor arising from the remnants of the notochord. Chordomas usually exhibit decreased uptake of 99mTc methylene diphosphonate (MDP) on bone scintigraphy.

CASE REPORT

A 37-year-old female patient with non-traumatic back pain for the last 2 months was found to have a soft tissue mass in the sacral region on magnetic resonance imaging, with destruction of the sacrum and coccyx, heterogeneous enhancement of L3-L5 vertebrae and invasion of both iliac bones. A chordoma was diagnosed on ultrasound guided fine needle aspiration. 99mTc MDP whole body bone scintigraphy [Figure 1] showed increased tracer uptake in the sacrum, L5 vertebra and both iliac bones. Hybrid single photon emission computed tomography/computed tomography (SPECT/CT) images of the pelvis showed increased tracer uptake in the sacrum and L5 vertebra with bilateral iliac involvement and extensive corresponding osteolysis [Figure 2].

Figure 1

99mTc methylene diphosphonate whole body bone scan showing increased tracer uptake in the pelvic bones and L5 vertebra. No other focal abnormality is seen in the skeleton

Figure 2

Hybrid single photon emission computed tomography/computed tomography images of the pelvis showing increased tracer uptake in the sacrum and L5 vertebra with bilateral iliac bone involvement and corresponding osteolysis

DISCUSSION

Chordoma is a slow-growing, locally aggressive tumor with a high recurrence rate and tendency to erode bone and soft tissues.[12] The earliest and most common symptom is sacral pain radiating to the legs. On bone scintigraphy photopenia is more common, possibly due to decreased vascular supply of bone or gross lysis of reactive bone.[345] Increased tracer uptake is infrequently reported and may be due to increased vascularity and mitotic activity in the tumor area.[6] Surgical resection remains the primary mode of treatment,[7] with adjuvant chemotherapy used when incomplete resection is suspected. The 5-year and 10-year survival rates are estimated to be 51% and 35% respectively. Chordomas often grow in inaccessible sites with ill-defined margins bordering adjacent soft tissues, making complete excision difficult. Hybrid SPECT/CT may have a role in management by better defining the margins of bony involvement.