Clinical History
A 73 year old man complained of ulnar wrist pain. A palpable mass was present in his left ulnar wrist, which had been known to him for years, but used to be painless until a week ago.
Imaging Findings
A 73 year old man was referred for imaging studies of the left hand and wrist. He complained of a mass in his ulnar wrist, which had been present for many years, but had become increasingly painful for about a week. The clinical examination confirmed a firm mass situated deep to the hypothenar musculature and extending to the dorsum manus. Dorsal extension of the wrist joint was slightly restricted. Apart from that, the patient’s past history was unremarkable. Plain radiographs of the left hand were obtained. The posteroanterior view showed a soft tissue mass which eroded the ulnar wrist bones and metacarpal bases (Fig 1). MRI better depicted the tumour extent amongst the wrist and metacarpal bones (Fig 2). The lesion completely surrounded the extensor carpi ulnaris tendon, but did not destroy it. On transverse sections, the tendon was situated near the centre of the mass, suggesting that it might have originated from the tendon sheath (Fig. 3). Based on the imaging findings, open excisional biopsy was performed and the specimen was sent to a national reference centre for soft tissue neoplasms, where the diagnosis of a benign, extraskeletal chondroma was made.
Discussion
The vast majority of hand and wrist masses are benign, and many of these have a distinctive appearance on imaging studies, especially MRI. The 3 most common hand and wrist lesions are ganglion cysts, giant cell tumours of the tendon sheath, and haemangiomas [1]. Other common lesions that can be diagnosed radiologically are lipomas, neural sheath tumours, and variant soft-tissue or bony structures [2]. Soft tissue chondromas of the wrist are quite rare. They are also particularly remarkable insofar as they do not arise in the expected location of a chondroma, exhibit similar signal characteristics to enchondromas on MRI (including possible calcifications), and may lead to cortical destructions, making them indistinguishable from malignancies [3]. Typical chondromas in adults arise from nests of chondrocytes within the meta- or diaphyseal bones (enchondroma) or in the periosteum (periostal chondroma). Soft tissue chondromas, on the other hand, are solitary, slowly-growing lesions, mostly involving the tendon sheaths of the hands or feet. However, they are benign neoplasms consisting of mature hyaline cartilage. As in their skeletal counterparts, large tumours may lead to cortical bone destructions, which may become painful. The pathologic features of this tumour type are variable. Focal fibrosis, calcification, ossification, or myxoid changes may occur [4]. Calcifications have been described in most previous reported cases [3]. This case is rather unusual, because there were no intralesional calcifications. On MRI, long T1 and T2 relaxation times in conjunction with a sharply marginated, lobular appearance are consistent with a cartilaginous lesion [3]. In masses of the wrist, less advanced than this one, familiarity with the features of extraskeletal chondroma may be of practical importance to avoid an overly aggressive treatment. However, given the extensive bony erosions of the present tumour, malignant degeneration had to be suspected in spite of the rather long history. Contrast was not administered in this case, but could have been useful to demonstrate an enhancement pattern typical for cartilaginous tumours. However, the lesion had to be biopsied at any rate.
Differential Diagnosis List
Soft tissue chondroma of the wrist
Final Diagnosis
Soft tissue chondroma of the wrist
