Elbow Soft Tissue Mass in a 9-Year-Old Boy

Abstract

LEARNING OBJECTIVES On completion of this activity, the reader should be able to: distinguish between different etiologies of tumoral calcinosis; identify the underlying etiologies; and outline an appropriate treatment course. HISTORY AND PHYSICAL EXAMINATION A 9-year-old boy was seen for evaluation of a mass at his right elbow. According to the patient’s family, the mass first was noticed 1.5 months before the initial visit. During the elapsed time, the mass reportedly continued to grow slowly. The patient had no pain associated with the mass. He otherwise was healthy with no significant medical history; pregnancy, development, and familial history were noncontributory. On physical examination, the patient appeared in good health. He reported no pain associated with the mass located in the posterior aspect of the right distal humerus. However, on deep palpation of the mass, mild tenderness was observed. The mass was measured at 5 cm × 3 cm × 2 cm. The patient had full ROM in the elbow, shoulder, and wrist, and the neurovascular examination to the extremity was normal. Radiographs taken at another institution showed a calcified mass posterolateral to the right elbow (Fig 1). Magnetic resonance imaging scans were taken (Fig 2). Blood tests were normal except for a phosphorus level elevated at 6.3 mg/dL (normal, 3.7–5.6 mg/dL).Fig 1.: A–B. (A) Preoperative radiograph of mass at the right elbow of a 9-year-old patient. The estimated size is 5 cm × 3 cm × 2 cm. (B) Lateral view of mass at right elbow of patient.Fig 2.: A–B. (A) An MRI scan of mass. (B) Sagittal MRI scan of the mass.Based on history, physical findings, and the imaging studies, what was the differential diagnosis? IMAGING INTERPRETATION There was a radiodense, homogeneous, lobulated, low signal, calcified mass posterior and lateral to the distal humerus. No other lesions were seen. No attachment to or erosion of the bone was seen. Bone mineralization was normal. The MRI scans showed an extraarticular, septated mass with no erosion, destruction, or thickening of the cortex. There was minimal adjacent edema. DIFFERENTIAL DIAGNOSIS The differential diagnosis of periarticular calcifications included: Idiopathic tumoral calcinosis Synovial osteochondromatosis Myositis ossificans Soft tissue sarcoma Tumoral calcinosis secondary to: Hypervitaminosis D Milk alkali syndrome Primary hyperparathyroidism Collagen vascular disease An open incisional biopsy with intraoperative frozen section was done (Fig 3). Based on the history, physical findings, radiographic studies, and pathologic results, what is the diagnosis and how should the lesion be treated?Fig 3.: A–B. (A) Histologic section of the tumoral mass (stain, hematoxylin and eosin, magnification, ×40). (B) Histologic section of the tumoral mass (Stain, hematoxylin and eosin; magnification, ×400).Continuation of ORP Conference from page 263. HISTOLOGY INTERPRETATION Histologically, the lesion was made up of nodules of a cellular dystrophic calcification, some of which were surrounded by a foreign body giant cell reaction. The lobules were separated by fibrovascular septae (Fig 3). DIAGNOSIS Idiopathic tumoral calcinosis DISCUSSION AND TREATMENT Based on the radiographic and laboratory evidence, the mass was determined to be tumoral calcinosis. The gross visual appearance of the lesion was consistent with that of tumoral calcinosis. After the incisional biopsy and intraoperative frozen section, excision of the lesion was done. The lesion was taken with its pseudocapsule and removed in its entirety. A smaller, satellite lesion also was removed. The masses were removed from the patient’s elbow (Fig 4). A triceps splitting approach was used to reach the masses. The masses measured 1.5 cm × 1.0 cm × 0.6 cm and 5.0 cm × 3.5 cm × 2.5 cm, respectively. The masses were irregular in shape, and were a pink-tanish red color. The external surface was partially smooth and glistening and partially ragged and irregular. There was a netlike fibrous layer over the exterior of the masses. Once sectioned, the masses revealed cysts filled with a tan-yellow semisolid material (Fig 5). There was no sign of malignancy on frozen section or final histologic evaluation.Fig 4.: Intraoperative photograph of the mass by the posterior aspect of the right distal humerus, before excision.Fig 5.: Close-up intraoperative photograph of the mass and its semifluid filling.The last followup visit at 3 months revealed normal ROM, an intact neurovascular examination, and no pain or recurrence (Fig 6).Fig 6.: A–B. (A) Radiograph of the right elbow, taken 2 months after the surgery with no signs of recurrence. (B) Lateral view of the right elbow, taken 2 months after the surgery. See page 264 for diagnosis and treatment.Tumoral calcinosis first was observed as a discrete process in 1899 by Duret, who called it “calcifying endothelioma.”4 However, it was Inclan, in 1943, who coined the term tumoral calcinosis.10 Today, tumoral calcinosis is recognized as a benign, albeit rare, condition.14 The condition seems to be more common in individuals of African or AfroAmerican decent, and individuals from topical climates. There seems to be no favoring of one gender over the other.15 The etiology of the illness is as yet unknown. Tumoral calcinosis usually occurs spontaneously as a painless soft tissue mass in the periarticular area of prominent joints.12 These soft tissue masses frequently are located about the hip, elbow, shoulder, knee, feet, and hands.9 The masses can grow at such a substantial rate, that they break through the skin. If this occurs, a pale yellow, chalky fluid can be observed draining from the wound. This fluid generally is considered sterile unless there seems to be a superimposed infection.7 Tumoral calcinosis has been observed in patients with a wide range of ages; however, it generally presents in patients in the first 3 decades of life.17 These patients otherwise are healthy individuals. Complications arising from tumoral calcinosis are rare.5 Although transmission from parent to child never has been documented in the literature, an approximate 30% incidence rate between siblings was observed by Barton and Reeves.2 The elevated phosphorus levels have been attributed to an inborn error of phosphorous metabolism, thereby causing hyperphosphatemia.1 As a general rule, all other counts should be in the normal range unless there is an underlying metabolic condition. When examining the radiographs of a patient, it is important to observe the patterning of the tumoral mass. The mass should appear well-defined, and usually is situated in close proximity to major joints. Histologically, there should be several lobules, separated by fibrous septa.11 These fibrous septa give the impression of cobblestones or chicken wire. The fluid-calcium levels occasionally can be seen on radiographs or CT scans.18 Because of the presenting symptoms of most patients with tumoral calcinosis, it is understandable that a diverse group of diseases are included in the differential diagnosis. Myositis ossificans was considered as part of the differential diagnosis. An indicator of this disorder is an elevated erythrocyte sedimentation rate and serum alkaline phosphatase count. This was not the case in the current patient. Additionally, the radiographic evidence was against this diagnosis, because myositis ossificans is characterized by a lesion that begins to ossify at the periphery and progress to the center. The gross appearance of myositis ossificans is that of shell of bone surrounding a soft, red-brown center. The intraoperative biopsy and frozen section negated the possibility of this as a final diagnosis. Soft tissue sarcoma is another possible diagnosis, albeit a rare one.8 This potential diagnosis is described more accurately as a whole class of diagnoses, because there are many different types of soft tissue sarcomas. There specific etiology is varied, and little is definitely known.6 If the mass were a high-grade sarcoma, it would be characterized by poor differentiation, minimal stroma, hypercellularity, hypervascularity, and extensive necrosis. The lack of other masses throughout the body would suggest against this type of sarcoma, because it is known to metastasize quickly.16 Conversely, if the mass were a low-grade sarcoma, it would be seen as locally invasive but rarely spread to distant sites. The most important feature is the architectural organization of the tumor. Soft tissue sarcomas are known to have a zonal arrangement and a radial configuration of the vessels.3 Neither one of these descriptions accurately matches the mass seen in the current patient. It is left to the pathologist to ultimately rule out the possibility of a malignant or benign soft tissue sarcoma. Synovial osteochondromatosis has a different radiographic picture when compared with tumoral calcinosis. Multiple cartilaginous nodules within the joint are the hallmark of the disorder. These nodules are rounded or oval calcified or ossified loose bodies. On gross examination, the nodules are white-gray, translucent hyaline cartilage. As a result of their physiology, patients with synovial osteochondromatosis most likely will present with pain, stiffness, and swelling. Synovial osteochondromatosis usually presents during the third through fifth decades of life. Tumoral calcinosis secondary to hypervitaminosis D also was considered initially as a result of the patient’s presenting findings. Masses similar to tumoral calcinosis sometimes occur in patients with hypervitaminosis D. However, this possible diagnosis was discarded on receipt of the results of the bloodwork. The central characteristic of hypervitaminosis D is abnormally high blood concentrations of calcium caused by the excess intake of vitamin D. The current patient had normal blood calcium values. Furthermore, because of the calcium being drawn from the bones, the bone mineralization would be decreased in hypervitaminosis D. Tumoral calcinosis secondary to milk-alkali syndrome also was considered as a possible diagnosis. The condition is the result of excessive intake of milk and soluable alkali. As a result, calcium deposits are found in the kidneys and other soft tissues including the musculoskeletal system. Again, abnormal calcium blood levels and bone mineralization are seen in patients with milk-alkali syndrome. Most patients with this condition present with nausea, vomiting, headache, and weakness, all of which were not exhibited by the current patient. A similar set of symptoms is seen in most patients suffering from tumoral calcinosis secondary to hyperparathyroidism. Conversely, some patients may present with no such physical symptoms. However, in this condition, as with several other differential diagnoses, the blood calcium generally is above normal, and bone mineralization is abnormal. Neither of these is true for the current patient. In addition, blood phosphorous levels are depressed, because excretion of phosphorus in the urine is increased. A final possibility was tumoral calcinosis secondary to various collagen vascular diseases. This collection of diseases includes rheumatoid arthritis, rheumatic fever, systemic lupus erythematosus, scleroderma, dermatomyositis, and periarteritis nodosa. Tumoral calcinosis may present as a secondary condition to one of the aforementioned collagen diseases, especially in older patients. In all of these diseases, the common histologic features are widespread inflammatory damage to connective tissues and blood vessels, and at times the deposition of fibrinoid material. However, work up of the current patient did not produce suggestion of a collagen disease in either histologic evaluation, physical examination, or the bloodwork. There is little consensus as to a proper course of treatment for children with idiopathic tumoral calcinosis. Some favor complete excision of the mass as soon as it has been discovered. Others argue that this is not a viable form of treatment, because if the mass is not fully excised, there is a good chance of recurrence.14 In adults, a powerful combination of drugs has been successful in some patients.14 However, there is a high risk in children of having ricketic bony changes develop in the immature skeleton.7 Irradiation has not been successful.13