The term tumoral calcinosis (TC) was initially proposed by Inclan and colleagues in 1943 for a disease characterized by large juxta-articular lobular calcified masses in patients showing normal serum calcium and phosphate levels. A commonly recognized classification for TC was introduced by Smack et al., who proposed a classification based on pathogenesis after retrospectively reviewing 122 cases of TC:(1)Primary Normophosphatemic TC,it is idiopathic, characterized by normal levels of calcium and phosphate with no biochemical abnormalities;(2)Primary Hyperphosphatemic TC,it is characterized by normal calcium, abnormal phosphate;(3) Secondary TC,it is associated with an underlying condition promoting deposition of calcium in soft tissue such as chronic renal failure, hyperparathyroidism or malignancy.Hence,based on the medical history, clinical presentation and serum electrolytes, it was concluded that our case fits into the secondary TC.UTC is a form of metastatic tissue calcification unique to dialysis patients, manifesting as painless and asymptotic masses in periarticular soft tissue.While the etiology and pathology of UTC remain poorly understood, a necessary condition is an elevated serum calcium-phosphate product[6–7].Prevalence of UTC increases with the number of years on hemodialysis,it was reported that the prevalence of UTC ranges from 0.5 to 3% in dialysis patients and may be underestimated due to lack of symptoms in its early stage,as well as many physicians were not be familiar with the symptoms,signs of the disease and its appearance on various imaging studies[9–10].In addition,it means that the diagnosis is at risk of being delayed for long periods and lack of recognition of complications of the disease. The most commonly involved sites in descending order are the hip, elbow,shoulder,foot and wrist[11–20],as well as the head,neck and spine less commonly[21–25].In general, the lesions do not involve the adjacent joint space or bone, but is often connected with surrounding soft tissue,the lesions usually grow slowly over a period of years, but may occasionally increase in size so rapidly over several months,it may cause compression symptoms, including pain, weakness or limitation of motion of the nearby joint and the skin may break down and a yellowish or milky fluid oozes from them when the lesions become very large.A long-standing lesion may undergo secondary chronic infection.
Radiologically, circular or oval, well demarcated mass of calcium and inhomogeneous appearance is characteristic.Histological features of UTC are distinctively different from the rest,there are characteristic compartments that contain both calcifications and liquid milky contents. The lesion is often encased by a dense fibrous capsule,frequently separated by fibrous trabeculae.A typical radiographic appearance and location,together with appropriate clinical history and laboratory data can strongly suggest this diagnosis.Nevertheless,a definite diagnosis of UTC requires histopathological confirmation from the tissue.
The differential diagnosis includes other conditions causing ectopic calcification,such as synovial osteochondromatosis, synovialsarcoma,myositis ossificans,tophaceous gout[28–29].With the use of radiography these diseases can be distinguished from UTC in the majority of patients,Tc-99m MDP whole-body bone scintigraphy reveals areas of increased uptake in the regions of lesions,it can provide us with clinically asymptomatic lesions.The authors contend that clinical,radiographic,and pathologic awareness of UTC is of paramount importance in preventing misdiagnosis of this lesion.
The exact mechanism of UTC is still unknown,so no approved effective therapy currently exists.Surgery may not be the first option due to the presence of multiple co-morbidities and higher risk of recurrence,the underlying disorder is primarily treated[30–31].A low-phosphate diet is an essential first step,primary treatment modalities consists of phosphate binders[32–33] and antacids, if this is ineffective,increasing urinary phosphate excretion by the administration of acetazolamide might be beneficial,this has been shown to reduce size of TC lesions to various degrees. Sevelamer may result in a decrease in serum phosphate level,but the response in the described cases in the literature was inconsistent,the benefits are limited and it could not prevent the progression of the lesion.Medical therapy is also used for TC patients,using low-calcium dialysate solutions, high-flux hemodialysis and increased length and frequency of hemodialysis treatments.Fatehi et al. reported a case that keeping on hemodialysis improved the symptoms and reduced the mass of the lesion.Surgical resection should be considered when calcinosis causes severe pain, neurologic dysfunction or joint function limitations.In addition,parathyroidectomy and renal transplantation have been performed,the role of parathyroidectomy is still controversial,it usually achieves remarkable resolution in dialysis patients with severe hyperparathyroidism and elevated serum alkaline phosphatase(ALP),but in the absence of secondary hyperparathyroidism with a markedly elevated PTH, parathyroidectomy should be avoided as it may not improve calcium and phosphorus control or favorably affect the underlying process.Successful renal transplantation can provides complete resolution of UTC by inducing a negative calcium balance[42–45].
Most cases of severe UTC require a combination approach for optimal management,it is important to consider the overall systemic health and fluid and electrolyte disorders in anuric patients.The surgical treatment of UTC possibly inducing hypocalcemia,as occurred in our case,the patient’s serum calcium levels suddenly decreased intraoperatively.It have proven to be a difficult problem from the standpoint of diagnosis as well as management and treatment.Indeed, the medical management of UTC is based on limited clinical evidence.Due to its rarity, systematic studies and randomized clinical controlled therapeutic trials are lacking and all available treatment information is based on case reports or case series with variable success rates. Assessment of treatment options is complicated by the variability between subjects in terms of the severity of biochemical abnormality and the number and size of calcinotic lesions.From a medical point of view, conservative measures for hyperphosphatemia are very important,from a patient’s perspective, the most important outcome is probably not only the resolution of calcified lesions but also a dramatic improvement of pain and function of joint range of motion.Efforts for uremic patients are focused on lowering serum phosphorus levels with dietary measures, dialysis therapy intensification, and use of phosphate binders, which have been shown to limit recurrence[46–47]. Surgical treatment has been recommended primarily for patients with pain, ulceration and functional impairment,medical treatment to control hyperphosphatemia is an important adjunct to surgical excision,it has been reported that the patient’s symptoms improved along with the decrease in serum phosphate levels.
At least three problems arise when attempts are made a surgical excision of UTC.First,the masses generally lack a true capsule,a radical removal may be difficult if no true capsule is present as the mass may extend into adjacent muscle tissues,as occurred in our case,fortunately,resolve the pain and normalize function of hip joint range of motion by incomplete surgical excision in our patient was indeed satisfactory.Second,surgical treatment may require wide excisions,resulting in wide sacrifice of muscles and tendons,leaving large tissue defects or major functional deficits, which necessitate the use of complex reconstructive methods.Major surgery should be avoided unless there is major dysfunction for the end objectives would be amelioration of pain, to normalize function of adjacent joint range of motion.In addition,we must also pay attention to the wound infection when take surgical resection of the UTC.And third,we had to face major therapeutic compliance problems in the management of UTC.