Oral Brown Tumors in Familial Hypophosphatemic Rickets

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 596-623-Case Reports: Pediatric Endocrinology & Metabolism
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-599
Dina Belachew*, Rebecca Glover Andrews, Heather Ilycia Baumhardt and Mark A Sperling
Children's Hospital of Pittsburgh, Pittsburgh, PA
Background: Familial hypophosphatemic rickets (FHR), also known as vitamin D-resistant rickets, is caused by multiple genetic mutations that result in hypophosphatemia and rickets due to renal phosphate wasting. This occurs mainly through alterations of the phosphaturic hormone fibroblast growth factor 23 (FGF 23). Patients present in childhood with classic manifestations of rickets such as skeletal deformities and growth retardation. Treatment is primarily targeted to improve phosphorus retention, but can result in secondary and tertiary hyperparathyroidism. Oral manifestations include dental abscesses, characteristic to this disease, and caused by abnormal dentin. In children with FHR, brown tumors associated with secondary hyperparathyroidism are rarely seen in the maxillae and mandibles. These tumors are clinically, radiographically and histologically indistinguishable from giant cell granulomas. Accurate diagnosis of brown tumors allows the clinician to treat the systemic condition causing the hyperparathyroidism.
Case Report: We report a case of a 14 year old male with hypophosphatemic rickets who presented to the dental clinic with oral lesions. He was taking oral phosphate replacement therapy along with calcitriol but had been poorly compliant with therapy.  At his dental evaluation, a panoramic radiograph was obtained and showed multifocal, multilocular lesions. The largest lesion was located in the anterior mandible and enveloped the two mandibular central incisors. Biopsy showed central giant cell lesion consistent with reparative giant cell granuloma. Laboratory data showed hyperparathyroidism with a PTH of 152 pg/ml (Normal range 9-69). Serum calcium was 9.2mg/dl (Normal range 8.8-10.8) and phosphorus was 2.6 mg/dl ( Normal range 2.3-4.5). Prior phosphorous levels had all ranged between 2.6-3.4mg/dl, calcium 9.2-9.5mg/dl and alkaline phosphatase 499-643 IU/L (Normal range <400). Although family history is strongly positive for FHR in all his three siblings, mother and maternal relatives, mutational analysis for the FGF23 and phosphate-regulating endopeptidaste (PHEX) genes were both negative. Additional genetic evaluation is being performed.
Conclusion: FHR can be complicated by secondary hyperparathyroidism. In our case, this was detected because of the finding of brown tumors in the anterior mandible. Treatment aims to normalize skeletal deformities and growth while avoiding potential complications such as nephrolithiasis and hyperparathyroidism.

Nothing to Disclose: DB, RGA, HIB, MAS

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm