Mesenchymal Chondrosarcoma, Clinicopathological Characteristics of an Uncommon Tumor

Abstract

Mesenchymal chondrosarcomas (MCS) are very rare malignant tumors. They comprise 2–10% of all chondrosarcomas. Approximately 600 cases of MCS have been published, as case reports and small series. In English language medical literature only three series include 20 or more cases have been described. This paper aims to document various histological findings, histological patterns that can be seen in MCS. In addition, demographic features, clinical and radiological findings and survival data are also incorporated to assess prognostic impact of various histological findings. This is a descriptive cross sectional study including cases of MCS diagnosed at Shaukat Khanum Memorial Cancer Hospital and Research Center, Lahore, Pakistan between 2002 and 2012. The slides were reviewed by two consultant pathologists independently and findings (pattern, cellularity, spindle cell component, necrosis, mitoses, hemangiopericytoma like vessels) were documented on a specially developed form. The clinical information was extracted from case files. Survival data was obtained by contacting the patient or their families in those cases for which contact numbers were available. Data analysis was done using SPSS 20.0. Of the total 18 cases, 10 were males (55.6%) and 8 were females (44.4%). Patients were most commonly in their second or third decades of life. Tumor locations included craniofacial bones (n=5, 28%), ribs and chest wall (n=3, 16%), spine (n=3, 16%), and the lower extremity bones (n=5, 28%). Extraskeletal sites included parapharyngeal region (n=1, 6%) and thigh (n=1, 6%). Histologically biphasic pattern was seen 16 cases (89%). Two cases showed sheets of round to spindle cells with very focal cartilaginous component (11%). Spindle cell component was seen in 14 cases. Necrosis was present in 7 cases (38.9%). Survival data was available for 11 patients (61%). Among these, n=7 (64%) patients developed metastatic disease. The mean survival for cases with metastatic disease was 14.2 months. In patients without metastatic disease, mean survival was 37 months. As the incidence of mesenchymal chondrosarcoma is extremely low, the limited number of patients discussed in most of the studies precludes statistically significant conclusions. MCS should be considered in the differential diagnosis, when pathologists encounter a bone and soft tissue tumor with biphasic pattern composed of round to spindle cell component and hyaline cartilage. Given the diagnostic pitfalls discussed, clinicians may consider obtaining larger biopsy specimens to limit sampling error or confirming the diagnosis with immunohistochemical stains or genetic analysis when a larger biopsy is not possible.