Tumor-induced rickets-osteomalacia: an enigma

Area of Science:

• Pediatric Endocrinology
• Oncology
• Skeletal Dysplasias

Background:

• Tumor-induced osteomalacia (TIO) is a rare paraneoplastic condition characterized by renal phosphate wasting.
• It leads to severe hypophosphatemia and osteomalacia, often mimicking hereditary rickets.

Observation:

• A pediatric patient presented with a five-year history of rickets, initially diagnosed as hereditary hypophosphatemic rickets.
• Despite treatment with phosphorus and calcitriol, skeletal deformities progressed, leading to surgical interventions and iatrogenic tertiary hyperparathyroidism.

Findings:

• A large, 10.5 cm thoracic mass secreting fibroblast growth factor-23 was identified.
• Histopathology confirmed a phosphaturic mesenchymal tumor, mixed connective tissue variant, establishing the diagnosis of TIO.
• Surgical excision of the tumor resulted in significant postoperative improvement.

Implications:

• TIO should be considered in pediatric patients with refractory hypophosphatemic rickets, especially when an associated mass is detected.
• Timely diagnosis and surgical management of the underlying tumor can correct the metabolic bone disease.
• This case underscores the importance of a comprehensive diagnostic approach for rare endocrine and oncologic disorders in children.