Chondrosarcoma of Second Toe Distal Phalanx-A Case Report

Chondrosarcoma is a relatively common primary malignant bone lesion. It is a malignant, relatively slow growing cartilage producing tumor. It forms approximately 10% of malignant primary bone tumors. However, it usually arises in long bones and truncal bones, whereas these tumors are uncommon in the hands and feet. The type are (A) Primary chondrosarcomas arises denovo from bone without any preexisting lesion. (B) Secondary chondrosarcomas when tumor arises from preexisting benign lesions of bone. Primary tumor is generally seen between 40 to 60 years of age. Secondary chondrosarcomas are more common in young adults.

It is a lobulated, translucent, bluish whitish cartilaginous mass with in medullary cavity. Endosteal aspect of cortex appears eroded and scalloped. Tumor spreads widely through medullary cavity, its extent is greater than it appears on X-rays. As tumor penetrates the cortex it is temporarily delimited by periosteum. New reactive new bone is formed at the periphery of sub periostealmass there by thickening the cortex. This is seen in slow growing and less malignant tumors.
In rapidly growing tumors periosteum is penetrated easily, so no reactive new bone formation. When a firm greyish tanned tissue without lobular configuration is found, it represents most malignant type. On removing the closely investing periosteum, the tumor appears lobulated, bluish white, shiny, opalescent or semitranslucent mass of firm texture or rubbery consistency.
The cut surface exhibits specks of calcification that impart a gritty sensation on palpation, gelatinous or myxoid areas and ragged cavities. The degree of calcification is greater in slower growing tumors.

Microscopic appearance
Histological features of cartilage should be noted to diagnose presence of a cartilaginous tumor. A normal chondrocyte is ellipsoid, ovoid or round in shape, has slightly scalloped surfaces. It contain a central, oval, sometimes indented nucleus with regularly distributed abundant chromatin and indistinct nucleolus.
Sarcomatous chondrocytes and their nuclei vary greatly in size, shape, number of nuclei and nucleoli chromatin content. Histology shows signs of malignancy including hyper cellularity, plumpness of nuclei, double nuclei in more than occasional cells, pleomorphism of cells and nuclei, hyperchromatism and mitotic figures. Mitotic figures are rare in low and medium grade tumors but are readily found in high grade tumors.

Radiological Features Central tumors
The lesion is seen in metaphysic or diaphysis of a long tubular bone. Rarely it may occupy epiphysis at juxtraarticular area, where it may be mistaken for a gaint cell tumor or chondroblastoma. The lesion is located in medullary cavity, it is large and ill defined. Countour of bone is enlarged or expanded. The cortex is focally or extensively eroded and thinned out. The inner cortex may have scalloped borders. Tumors will have specks of calcification and cotton whorl appearance. Slow growing tumors will show a greater of calcification where as highly malignant rapidly growing tumors will show little or no calcification and often destroys the cortex without expanding shaft. There is a associated soft tissue mass.

Low grade features
Dense calcification forming rings or specules with eccentric lobular growth of a soft tissue mass

High grade features
Faint amorphous calcifications with large non calcified areas and concentric growth of soft tissue mass.
This article presents the case of a 60-year-old woman with a chondrosarcoma in the distal phalanx of the left second toe. Radiography showed bony mass extending from the distal phalanx. Histologically, the tumor was classified as grade 1 chondrosarcoma [1][2][3][4][5][6].

Local examination (left 2 nd toe)
• Irregular well defined Swelling over the distal phalanx 2 X 3cms.
• Heterogenous consistency ranging from firm to bony hard.
• Adherent to underlying soft tissues and Immobile.

Discussion
Chondrosarcoma of the foot is rare. Correct classification of the grade of chondrosarcoma is extremely important because the prognosis and treatment are different for different stages and grades (Table 1). Evans et al. used their own grading system: low grade is a low-levelmalignancy, intermediate grade is moderately malignant, and high grade is highly malignant. The chondrosarcoma of the phalanx is rare but, when present, extirpation is necessary to prevent growth and spread. Therefore, every effort should be made to differentiate between enchondroma and chondrosarcoma in each case. Complete wide excision of the lesion and cartilage cap should not be violated during resection of chondrosarcoma arising out of osteochondroma as it will increase the risk of local reccurence.

Conclusion
Phalangeal chondrosarcoma behaves as locally aggressive lesion and rarely metastasize. Curettage with local adjuvant and adequate followup can be tried as the first-line management, especially where amputation would lead to significant loss of function.