Based on the history, physical findings, radiographic studies, and histologic picture, what is the diagnosis, and how should this patient be treated?
The excised lesion measured 5 × 2 × 2 cm (Fig 3). The external surface was tan-red. After removal, the specimen was split down the center revealing cartilaginous portions of tan-red to white friable tissue. Frozen section showed a paucicellular fibromyxoid lesion without significant atypia. Permanent section showed a benign cartilaginous lesion with mild cellular pleomorphism and hyperchromasia within a myxoid (Fig 4A), myxoid-hyaline (Fig 4B), and hyaline (Fig 4C) matrix. Focal mild atypia was present with periosteal permeation, but absence of periosteal invasion.
Periosteal (juxtacortical) chondroma of the right humerus
TREATMENT AND DISCUSSION
The clinical, radiographic, and pathologic findings in this case were consistent with periosteal chondroma. Unlike the lesion in the current case, chondrosarcomas usually invade the marrow space and have a malignant histologic picture. 13 Furthermore, chondrosarcomas typically occur in patients in the fourth to sixth decades of life, making it extremely unlikely in the current case of an 8-year-old boy. Periosteal desmoid was unlikely based on the location of the lesion and radiographic and histologic features; periosteal desmoid is characteristically metaphyseal (usually in the distal femoral metaphysis) and contains uniform fibroblasts among thick, wavy bundles of collagen. Periosteal osteosarcoma was ruled out because of the benign appearing radiographic picture and absence of malignant cells in the histologic section. Finally, aneurysmal bone cyst was ruled out by the absence of a characteristic expansile thin-shelled lesion with blood-filled, honeycombed cavities.
Periosteal chondroma is an uncommon, benign, slow growing, cartilage tumor that arises on the surface of bone. The lesion first was described as a distinct clinical entity in 1952 by Lichtenstein and Hall. 6 Since then, more than 165 cases have been described in the literature as reported by Lewis et al. 5 Nojima et al 9 reported the presence of 46 periosteal chondromas from more than 7000 primary bone tumors on file at the Mayo Clinic. Brien et al 3 reported on 16 cases of periosteal chondroma representing 1.3% of all cartilage tumors. Schajowicz 13 reported 18 periosteal chondromas among 576 chondromas. The tumor has its highest incidence in patients in the second decade of life, with mean ages reported from 23 to 28 years, but a wide range of ages (range, 1 year –73 years) also was observed. 1,2,4,5,9 The lesion can involve almost any bone but most commonly is found in the proximal humerus. 1–5,7,9–12,14,15 Lewis et al 5 reviewed the literature from 1925 to 1985 and found only two cases of midhumerus periosteal chondromas among the 165 cases identified. The current patient had an uncommon location of an uncommon tumor.
The most common presenting complaints of patients with a periosteal chondroma include swelling, pain, and a mass. Boriani et al 2 reported that 12 of 20 patients presented with a pattern of swelling followed by moderate pain at an average of 21 months later. Similarly, Bauer et al 1 described six of 14 patients presenting with mild pain, three of whom also had a mass, and four patients presenting with a painless mass. They also reported that the masses had been present for 1.5 to 5 years. In addition, four patients began to experience pain after an incident of trauma to the arm, and in four other patients, the lesion was discovered incidentally on radiographs. 1 Nojima et al 9 reported on 31 patients from a series of 46 patients who experienced symptoms. Of these 31 patients, 11 had swelling, 12 experienced pain, and eight had a painful mass. The pain most frequently was described as mild and intermittent, and the duration of symptoms ranged from 1 month to 7 years. 9 Therefore, the current patient presented with a fairly typical history of a mass and pain, with the pain beginning after trauma (wrestling), and 2-year duration of symptoms.
The radiographic appearance of periosteal chondromas was described most completely in 1981 by deSantos and Spjut. 4 In a review of 22 cases of histologically-proven periosteal chondroma, they described the features of cortical scalloping or remodeling of the adjacent bony cortex, the presence of cartilaginous matrix, and the possibility of soft tissue involvement. 4 DeSantos and Spjut identified cortical scalloping in 16 of 22 cases, and observed that the remodeling cortex always was well-defined and slightly sclerotic with no evidence of fracture. They reported the presence of a radiographically-recognized cartilaginous matrix in 18 patients, and a distinct soft tissue mass in eight patients. 4 Although these features are considered the characteristic radiographic features of periosteal chondroma, the combination of the three features was present together in only 30% of the cases. Most tumors have been described as being between 2 and 3 cm in diameter. 1–3,7–9,12,14,15
Varma et al 14 described the characteristics of periosteal chondroma on MRI scans. They describe the lesion as having intermediate signal intensity on T1-weighted imaging and high intensity on T2-weighted imaging. Those characteristics of a benign soft tissue lesion such as distinct margination without encasement of the neurovascular bundle or underlying bone also were emphasized. 14
The lesion in the current patient had an unmineralized matrix and saucerization of the cortex (an apparent shallow depression formed by eccentric excavation of bone). In addition, a rim of cortex was observed between the medullary cavity and the lesion without evidence of involvement of the neurovascular bundle. Except for the unusual diaphyseal location of the lesion, it possessed many of the characteristic radiographic features of a periosteal chondroma.
Grossly, periosteal chondromas typically are well-defined, ovoid tumors comprised of benign cartilage and located within an eccentric, scalloped-out underlying cortex. They usually are blue-gray to white on cut section, and almost never invade the medulla. 9,13 Nojima et al 9 described a series of 46 patients with periosteal chondroma in which 33 had hypercellularity, nuclear enlargement, hyperchromasia, double-nucleated cells, or myxoid change of the matrix, as seen in the current patient (Fig 3). Other series have shown similar results. 1–4 All of these features may be considered signs of low-grade malignancy, underscoring the importance of integrating radiologic data with histologic data when making a diagnosis. The current case revealed white, friable tissue on cut section. It was observed to have myxoid change and mild atypia, but periosteal invasion was not seen. Therefore, this lesion had several of the features common to periosteal chondroma.
The treatment of choice for patients with periosteal chondroma is marginal excision with or without bone grafting. 1,3,5,7,9,15 Lewis et al 5 reviewed the literature and reported a local recurrence rate of only 3.6% among 165 patients with periosteal chondroma. Although intralesional curettage is a successful treatment for many patients with periosteal chondromas, recurrence has been reported after intralesional surgery. 1,5,7,11,15 Mora et al 7 contend that the reported cases of local recurrence can be attributed to inadequate, intralesional excision. Marginal or wide excision of these benign, but locally aggressive lesions reduces the risk of recurrence. In the current authors’ opinion, marginal excision is preferred over intralesional excision when this is possible without creating a significant functional loss. Marginal excision was done in the current patient without increased risk of morbidity. Care was taken to protect the radial nerve; the deltoid insertion was maintained. The patient currently is asymptomatic 12 months after surgery with full range of motion, intact neurovascular status, and no signs of recurrence.
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© 2002 Lippincott Williams & Wilkins, Inc.
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