Chondromyxoid Fibroma of Scaphoid: a Rare Case

Chondromyxoid fibroma is a rare benign cartilage-forming tumor, counting for 0.5% of all primary bone tumors . The development of Chondromyxoid fibroma in the carpal bones is extremely rare. This article describes a rare case report of Chondromyxoid Fibroma in Scaphoid bone of a 15 year male. To our knowledge, this is the first report of Chondromyxoid fibroma in Scaphoid. The rarity of the lesion, together with its misleading clinical -radiological and histopathological features, prompted us to report our case. Indroduction: Chondromyxoid fibroma, a rare chondroid tumor, consisting of a mixture of fibromyxoid tissue and cartilage tissue in variable proportions and accounting for 0.5% of all primary bone tumors and 2% of benign bone tumors, occurs predominantly in adolescents and young adults and more commonly in males than in females (2:1) [13]. This tumor has a predilection for the bones of the lower extremities, usually the proximal tibia. Small bones of hand and feet including vertebrae are rare sites [15,16,17,18]. Only a few isolated cases of chondromyxoid fibroma affecting carpal and metacarpal bones have been reported [1, 3, 11, 12]. CASE A 15-year-old boy presented with a 7-month history of intermittent vague pain and progressive increasing swelling in the region of the wrist of his left hand with inward deviation of hand and weakness of grip strength for last 4 month. No history of trauma, or complaints suggestive of infection. Physical examination showed a eccentric swelling of about 7x 5 cm size ( fig 1) localised on radial aspect of left wrist with overlying skin normal, fixed tender and variegated consistency, overlying tendons free .Movement at wrist was restricted and painful. No distal neurovascular deficit. No involvement of other bones. Laboratory tests were unremarkable. A radiograph of his left hand showed a expansile bony growth arising from distal part of scaphoid with multiple lobular, septed, intact cortex, marginal sclerosis, cortical thinning and without obvious matrix mineralization and no new bone formation. There was associated osteopenia of other bone( fig 2). It was concluded that the tumor was likely to be benign and the differential diagnosis included enchondroma, aneurismal bone cyst, giant cell tumor and osteoblastoma. Fine needle aspiration cytology showed features of acute inflammatory lesion. MRI revealed multiple cystic lesion associated with fluid –filled level involving Scaphoid causing its expansion and no obvious area of cortical breach, confirming to Aneurysmal bone cyst( fig 3a,3b) .We planned for Scaphoidectomy and limited wrist arthodesis At surgery , a radiodorsal incision given, bulging bony mass from distal part of Scaphoid with surrounding fibrosis encroaching lunate making hard for smooth removal of Scaphoid( fig 4 a). As a result Lunate was also sacrificed and scapholunatectomy was performed. All precaution was taken to avoid damage to volar carpal ligaments. Gross examination of Scaphoid showed replacement of entire medullary cavity with spongy, gelatinous material ( fig 4 b, c). There was breech of cortex at capitate articular surface without involvement of capitate. Lunate was firmly adhered to Scaphoid .There was no change in radial and ulnar articular surface. Finally total wrist arthodesis with 3.5 mm recorn plate and auto iliac cancellous bone grafting was done ( fig 5). Histopathology reported band-like peripheral cellular condensation surrounding and dividing the pale-staining matrix-rich central parts of tumor in low power ( fig 6a). Large lobulated areas of spindle-shaped or stellate cells distributed within abundant myxoid or chondroid intercellular material in high power ( fig 6b). A characteristic finding was the increased cellularity of the tissue near the septa. These findings concluded the diagnosis of Chondromyxoid Fibroma. Fig 1. Eccentric Swelling of about 7x 5 cm size localised to radial aspect of left wrist with overlying skin normal