Uremic leontiasis ossea

Abstract

Uremic leontiasis ossea is a rare manifestation of renal osteodystrophy clinically characterized by jaw enlargement, widening of the nares, flattening of the nasal bridge, and increased interdental spacing. Computed tomography (CT) findings are particular characteristic and include serpiginous tunneling within the maxillofacial bones and cortical bone resorption. Nuclear medicine scans are also useful for demonstrating hyperplasia of the parathyroid glands. Ultimately, the diagnosis of uremic leontiasis ossea can be made non-invasively through a combination of clinical parameters and imaging findings, as described in this article.

The patient is a 28-year-old female with a history of end-stage renal disease diagnosed eight years before, tachycardia, and hypertension, who presented with progressive facial swelling for the last 3 to 6 months. The patient reported that the facial swelling gradually became hard and “bone like” and that the spaces between her teeth became widened, but denied associated pain. The patient also noticed changes in her fingers. Physical examination demonstrated facial deformity with bilateral diffuse maxillary and mandibular prominence and palpable masses in the region of the thyroid. A parathyroid panel was obtained with the following results: intact PTH of 3627 pg/mL (normal range: 15–75 pg/mL), serum calcium level of 10.1 mg/dL (normal range: 8.4–10.2 mg/dL), inorganic phosphate of 6.5 mg/dL (normal range: 2.5–4.4 mg/dL), serum alkaline phosphatase of 598 U/L (normal range: 30–120 U/L), and 25-Hydroxy Vitamin D of 14 ng/mL (normal range: 10–52 ng/mL). A non-contrast maxillofacial CT was performed ( Fig. 1 ), which showed diffuse expansion of the maxilla and mandible with thinning of the cortical bone and serpiginous lucencies within the bone marrow. A “salt and pepper” appearance of the skull was also apparent on CT along with diffuse cortical resorption ( Fig. 2 ). A Tc-99m sestamibi scintigraphy scan demonstrated four foci of radioisotope accumulation in the neck, consistent with parathyroid hyperplasia ( Fig. 3 ).