Oncogenic Osteomalacia: Challenges in Diagnosis

Area of Science:

• Oncology
• Endocrinology
• Radiology

Background:

• Osteomalacia can be caused by mesenchymal tumors, a rare condition often diagnosed late.
• Head and neck tumors causing osteomalacia are exceptionally uncommon.
• Chronic muscle pain and weakness are key symptoms of oncogenic osteomalacia.

Purpose of the Study:

• To report a rare case of mesenchymal tumor-induced osteomalacia in the head and neck.
• To review the utility of fluorodeoxyglucose-positron emission tomography-computed tomography (FDG PET-CT) and octreotide scanning in tumor localization.
• To highlight diagnostic and therapeutic strategies for oncogenic osteomalacia.

Main Methods:

• Case presentation of an elderly male with a 7-year history of debilitating muscle pain and weakness.
• Initial imaging with FDG PET-CT showing uptake in the ethmoid region.
• Subsequent imaging with DOTA-1-NaI3-octreotide (DOTANOC) scan revealing a tumor in the medial rectus region.
• Surgical excision of the identified tumors and histopathological analysis.
• Clinical and biochemical assessment for improvement post-surgery.

Main Results:

• The patient presented with symptoms consistent with oncogenic osteomalacia.
• FDG PET-CT identified a potential tumor site, but its excision did not lead to significant improvement.
• DOTANOC scan successfully localized the culprit tumor in the medial rectus.
• Histopathology confirmed a phosphaturic mesenchymal tumor.
• Postoperative improvement in symptoms and biochemical parameters confirmed successful treatment.

Conclusions:

• Octreotide-based PET-CT is highly sensitive for localizing tumors causing oncogenic osteomalacia.
• FDG PET-CT is a viable alternative when octreotide-based imaging is unavailable.
• Surgical resection of the phosphaturic mesenchymal tumor led to clinical and biochemical recovery.
• This case underscores the importance of considering rare tumor types in the differential diagnosis of osteomalacia.