Staging studies for evaluation of squamous cell carcinoma. Staging of left temporal squamous cell carcinoma with PET-CT.

Abstract

Primary hyperoxaluria is a rare congenital disorder of abnormal glyoxylate metabolism with resultant over-accumulation of oxalate, which then binds with calcium and precipitates in the kidneys, resulting in nephrocalcinosis and nephrourolithiasis. As renal function worsens, patients develop systemic oxalosis with calcium oxalate deposition in the soft tissues, musculoskeletal system, cardiovascular system, central nervous system, and eyes [1–5]. There are three common types of primary hyperoxaluria (types I–III). Type I is the most common and severe and involves a mutation in the alanine glyoxylate aminotransferase (AGT) enzyme causing overproduction of oxalate glyoxylate [1]. Type II results from deficiency of glyoxylate reductase and hydroxypyruvate reductase (GRHPR), which results in overproduction of oxalate and L-glyceric aciduria [1, 5]. Type III results from mutation in 4-hydroxy-2oxoglutarate aldolase (HOGA) and is the least aggressive hyperoxaluria type, with most patients not progressing to end-stage renal disease (ESRD) [1]. Imaging findings in primary hyperoxaluria vary depending on patient age and renal function [2–6]. Prior to renal function impairment, imaging is frequently normal. As renal failure develops, cortical nephrocalcinosis and nephrourolithiasis will be seen (Fig. 1). Calcium oxalate subsequently deposits in soft tissues, tendons, and joint capsules, with joint effusions and nodular-appearing tumoral calcinosis (especially in periarticular regions, which can cause erosive arthropathy) [2–6]. As ESRD develops toward the late stage of the disease, musculoskeletal imaging manifestations typically associated with renal osteodystrophy and secondary hyperparathyroidism will develop, such as osteosclerosis, subperiosteal resorption, Brugger-jersey^ spine, and vascular/soft tissue calcifications (also seen in Fig. 1). Abnormal skeletal maturation and pathologic fractures with delayed healing can also be seen but are similarly nonspecific. Oxalate deposition in the subcutaneous and dermal tissues can cause skin necrosis/ulceration, and oxalate deposition in the myocardium, pericardium, ocular and vascular regions has also been described [4–9]. Skeletal findings more specific to primary hyperoxaluria may include irregular diametaphyseal transverse sclerotic bands and wide metaphyseal zones [5]. Lytic lesions can be seen in primary hyperoxaluria, which histopathologically represent foci of calcium oxalate deposition with a granulomatous foreign body histiocytic reaction, which appear essentially identical to brown tumors on The case presentation can be found at doi: 10.1007/s00256-015-2161-1.