Tumor-induced osteomalacia: experience from three tertiary care centers in India

Abstract

Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome characterized by recalcitrant hypophosphatemia. Reports from the Indian subcontinent are scarce, with most being single center experiences involving few patients. Herein, we conducted a retrospective analysis of 30 patients of TIO diagnosed at three tertiary care hospitals in India. Patients with persistent hypophosphatemia (despite correction of hypovitaminosis D), normocalcemia, elevated alkaline phosphatase, low TmP/GFR and elevated or ‘inappropriately normal’ FGF23 levels were labeled as having TIO. They were sequentially subjected to functional followed by anatomical imaging. Patients with a well-localized tumor underwent excision; others were put on phosphorous and calcitriol supplementation. The mean age at presentation was 39.6 years with female:male ratio of 3:2. Bone pain (83.3%) and proximal myopathy (70%) were the chief complaints; 40% of cases had fractures. The mean delay in diagnosis was 3.8 years. Tumors were clinically detectable in four patients (13.3%). The mean serum phosphate was 0.50 mmol/L with a median serum FGF23 level of 518 RU/mL. Somatostatin receptor-based scintigraphy was found to be superior to FDG-PET in tumor localization. Lower extremities were the most common site of the tumor (72%). Tumor size was positively correlated with serum FGF23 levels. Twenty-two patients underwent tumor resection and 16 of them had phosphaturic mesenchymal tumors. Surgical excision led to cure in 72.7% of patients whereas disease persistence and disease recurrence were seen in 18.2% and 9.1% of cases, respectively. At the last follow-up, serum phosphate in the surgically treated group was significantly higher than in the medically managed group.

Nonremission and Recurrent Tumor-Induced Osteomalacia: A Retrospective Study

“…The result of our cohort may provide convincing evidence for this predicament. We found that the disease was equally prevalent in women and men, which is consistent with previous reports, but our results suggest that the refractory risk in women is twofold to threefold higher than that in men. To our knowledge, this finding is difficult to explain.…”

“…More than 70 cases in the head/neck have been reported in addition to the cases reported from our institute, and only 10 cases among them were refractory. (4,11,12,(14)(15)(16) Although this rate is higher than ours, it is plausible that TIO tumors in the head/neck have a favorable outcome. It does not make sense to compare the delicate differences between our cases and those reported in various institutes because other cases are so scattered.…”

“…Among each tumor location, head/neck tumors exerted the highest recovery rate, whereas spine tumors were most likely to be refractory. More than 70 cases in the head/neck have been reported in addition to the cases reported from our institute, and only 10 cases among them were refractory . Although this rate is higher than ours, it is plausible that TIO tumors in the head/neck have a favorable outcome.…”

“…The overall recovery rate was 88.4% in our cohort. Previously reported recovery rates in other studies have varied from 72.7% to 100% . Small sample sizes, gaps in medical resources, focuses on different tumor locations, and different follow‐up periods of these studies all led to discrepancies.…”

“…Previously reported recovery rates in other studies have varied from 72.7% to 100%. (4,5,(9)(10)(11)(12) Small sample sizes, gaps in medical resources, focuses on different tumor locations, and different follow-up periods of these studies all led to discrepancies. The result of our cohort may provide convincing evidence for this predicament.…”