Skeletal scintigraphy as an important complement for detecting bone metastasis from nasopharyngeal carcinoma

Abstract

Bone metastasis occurs frequently in patients with nasopharyngeal carcinoma (NPC). Although fluorine-18 fluorodeoxyglucose positron emission tomography with computed tomography (PET/CT) has been proven to be more sensitive at detecting bone metastases than Technetium-99m methylene diphosphonate skeletal scintigraphy in pretreatment patients with NPC in most clinical settings, there have been metastatic lesions that were positive on skeletal scintigraphy but negative on PET/CT scans. Herein, we report the case of a patient with stage IV NPC that manifested as multiple metabolically abnormal lesions on pretreatment skeletal scintigraphy and were considered malignant although they were negative on PET/CT examination. Follow-up evaluations with both skeletal scintigraphy and PET/CT scans as post-therapeutic imaging are also presented.

Keywords: Technetium-99m methylene diphosphonate; bone metastasis; case report; fluorodeoxyglucose positron emission tomography/computed tomography; nasopharyngeal carcinoma; skeletal scintigraphy.

Figure 1.

A 32-year-old male patient with nasopharyngeal carcinoma (NPC). Pretreatment staging with Technetium-99m methylene diphosphonate (Tc-99m MDP) skeletal scintigraphy ((a) anterior view; (b) posterior view) detected abnormal metabolic lesions, especially in left frontal skull, sternal end of the right clavicle (with posterior shine-through), T9 thoracic vertebral body, sacrum, right ilium near the sacroiliac junction, lower portion of the right acetabulum, and right femoral greater trochanter (all with arrows). Focal increased uptake in the maxillae and left mandibular area suggested certain dental problems.

Figure 2.

Pretreatment fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) scan of the 32-year-old male patient with nasopharyngeal carcinoma (NPC)/((a), (c), (e), CT images; (b), (d), (f), PET images). FDG PET/CT detected osteosclerotic lesions (i.e., T9 vertebral body, sacrum, right ilium near the sacroiliac junction, and lower portion of the right acetabulum, all with arrows) with barely any FDG abnormalities where skeleton scintigraphy showed abnormal radiotracer accumulation.

Figure 3.

Post-therapeutic imaging evaluation with Technetium-99m methylene diphosphonate (Tc-99m MDP) skeletal scintigraphy ((a), anterior view; (b) posterior view). Marked improvement with nearly no abnormal uptake was noted on skeletal scintigraphy after the patient completed chemotherapy and radiation therapy for NPC.

Figure 4.

Post-therapeutic imaging evaluation with a fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) scan ((a), (c), and (e), CT images; (b), (d), and (f), PET images). The FDG PET/CT revealed that previous osteosclerotic lesions with barely any FDG abnormalities had been resolved.