| Abstract|| |
Primary hyperparathyroidism (pHPT) is a condition caused by excessive and uncontrolled secretion of parathyroid hormone. The classical presenting symptoms in primary hyperparathyroidism are renal stones, hypercalcemic crisis, soft tissue calcifications, and cystic bone disease. Although most cases of pHPT are detected early and before symptomatic lesions appear, some patients may present late in the course of their disease. In this report, we present a patient with extensive parenchymal calcifications forming a cast of the right kidney which is called as "putty kidney" with Brown tumor located in the pubic ramus.
|How to cite this article:|
Batur A. Primary hyperparathyroidism causing putty kidney with brown tumor located in the pubic ramus. Saudi J Kidney Dis Transpl 2016;27:1033-6
|How to cite this URL:|
Batur A. Primary hyperparathyroidism causing putty kidney with brown tumor located in the pubic ramus. Saudi J Kidney Dis Transpl [serial online] 2016 [cited 2020 Oct 30];27:1033-6. Available from: https://www.sjkdt.org/text.asp?2016/27/5/1033/190883
| Introduction|| |
Primary hyperparathyroidism (pHPT) is a condition caused by excessive and uncontrolled secretion of parathyroid hormone (PTH) by abnormal parathyroid gland(s). The incidence of pHPT is estimated to be 20/100,000 and more than 80% of cases are asymptomatic at the time of diagnosis.  The classical clinical manifestations of pHPT are "stone and bone" disease. Renal manifestations of pHPT include hypercalciuria, nephrolithiasis, nephrocalcinosis, and chronic renal insufficiency. The presence of a renal stone (symptomatic or asymptomatic) categorizes pHPT as symptomatic.  Primary HPT in its classical form presents with a number of skeletal radiological manifestations; however, such findings are now rare.
| Case Report|| |
A 33-year-old patient with long-standing fatigue and occasional bone pain came to the emergency room complaining of left flank pain for the last four weeks. Physical examination revealed a blood pressure of 110/80 mm Hg, pulse rate of 80, respiratory rate of 24, and temperature of 37°C. Laboratory investigations showed a serum hemoglobin level of 8.6 g/dL, hematocrit of 25.3%, blood urea nitrogen of 227 mg/dL (normal 15-44), and creatinine of 16.2 mg/dL (normal 0.5-1.2). Other laboratory data showed elevated serum calcium (13 mg/dL) and intact PTH (223 pg/mL), confirming the diagnosis of pHPT. There was no other abnormality detected.
Chest radiograph was normal. Abdominal radiography demonstrated that the right kidney was completely calcified, and there were multiple lytic bone lesions [Figure 1]. Noncontrast-enhanced computed tomography showed widespread bone resorption and diffuse, uniform, extensive parenchymal calcifications forming a cast of the right kidney with autonephrectomy, which is called as "putty kidney" [Figure 2]a and b. The left kidney was atrophic and contained calcifications. There was also a hypodense, expansile lytic lesion of the inferior ramus of the right pubis extending to the soft tissue. The cortex was thinned [Figure 3]. Histopathology of a biopsy specimen showed fibroblastic proliferation and abundant giant cells which supported the diagnosis of a brown tumor.
|Figure 1: Abdominal radiography showing completely calcified right kidney (arrows) and diffuse, multiple lytic bone lesions.|
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|Figure 2: Noncontrast-enhanced computed tomography (a) widespread bone resorption and (b) diffuse, uniform, extensive parenchymal calcifications forming a cast of the right kidney which is called "putty kidney" (long arrow). The left kidney is atrophic and contains calcifications (short arrow).|
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|Figure 3: Contrast-enhanced computed tomography shows a hypodense, lytic lesion of the inferior ramus of the right pubis extending to the soft tissue (long arrows). The cortex is thinned (short arrows).|
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| Discussion|| |
The term "hyperparathyroidism" connotes a situation in which circulating concentrations of PTH exceed upper limits of age-specific normal range. Because the circulating half-life of this peptide hormone is a few minutes, high plasma concentrations reflect PTH hypersecretion. Primary HPT is characterized by high concentrations of PTH in association with elevated plasma calcium concentrations.  Primary HPT is two to three times more commonly seen in women with a peak incidence between the 5th and 6th decades of life.  The prevalence increases with age in both sexes. 
The classical manifestations of pHPT are renal stones, hypercalcemic crises, soft tissue calcifications, and cystic bone disease. Other manifestations include hypertension, gout and pseudogout, peptic ulcer, pancreatitis, hyperlipidemia, and diabetes. 
Nonspecific symptoms such as malaise and fatigue, bone or joint pain, muscle weakness, and nonspecific gastrointestinal complaints including constipation and weight loss may occur.  However, after including measurement of serum calcium levels in the routine checkup program in many developed countries, the number of asymptomatic cases has been increasing.
The major renal consequences of pHPT are nephrolithiasis and rarely, nephrocalcinosis. The latter, by definition, consists of diffuse precipitation of calcium salts within the renal parenchyma. Formation of calcium-containing stones in pHPT can be attributed to hypercalciuria. In pHPT, there is also an increased excretion of stone promoting substances, which facilitates calcium salt precipitation. 
Renal stone disease is a multifactorial disease, which may explain why some patients with pHPT develop nephrolithiasis and others do not. There is, however, no explanation for the fact that pHPT associated with renal stone disease is characterized by slight or even intermittent hypercalcemia. The frequency of hypercalcemia due to pHPT has been shown to be between 1.6 and 2.3% and in a series of patients with pHPT diagnosed by screening, renal stone disease was found in 2-7%.  Extensive parenchymal calcification in a lobar pattern with autonephrectomy, similar to the presented case, is called "putty kidney" and is characteristically seen in end-stage tuberculosis; however, there was no history of tuberculosis in our patient. 
It is generally accepted that bone involvement is a late manifestation of pHPT. However, this entity has become rare because most cases of pHPT are detected early and before symptomatic bone lesions appear. However, some patients may present late in the course of their disease.  pHPT in its classical form presents with a number of overt skeletal radiological manifestations, the most specific of which is the subperiosteal erosion occurring typically in the radial aspect of the second and third phalanges. More recent studies of pHPT indicate that there is a preferential effect on cortical bone and that trabecular bone is preserved.  Brown tumor, which is the bony lesion of pHPT, is caused by increased circulating levels of PTH, which results in increased osteoclastic bone resorption. The differential diagnosis should include giant cell granuloma, aneurysmal bone cyst, and "brown tumor" of HPT. Incisional biopsy can differentiate pHPT from others. 
The characteristic laboratory findings of pHPT are elevated serum calcium level and increased or normal PTH level. Secondary HPT is usually hypocalcemic but can be normocalcemic.  Well-known characteristic radiological changes of severe HPT such as "salt and pepper" skull due to subperiosteal bone resorption and periosteal neoostosis are not often encountered in patients with pHPT, but are more frequent in patients with secondary HPT resulting from end-stage renal disease. 
| Conclusion|| |
Although most cases of pHPT are detected early and before symptomatic lesions appear, some patients may present late in the course of their disease. The major consequences of HPT on renal structure and function are nephrolithiasis and nephrocalcinosis. There is a preferential effect of HPT on cortical bone and, Brown tumor may occur as a result of increased osteoclastic bone resorption.
Conflict of interest: None declared.
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Department of Radiology, Dursun Odabas Medical Center, Yuzuncu Yil University, Van, 65080
[Figure 1], [Figure 2], [Figure 3]