Extraskeletal mesenchymal chondrosarcoma arising from soft tissues: A rare case report

Abstract

Background: Chondrosarcomas are an exceedingly rare form of cancer, impacting only a few individuals per million. Among chondrosarcomas, a small fraction belongs to the mesenchymal sub-type. Furthermore, only one-third of mesenchymal chondrosarcomas manifest in extraskeletal locations.

Case: A 38-year-old woman was referred by a midwife after experiencing pain in the right upper quadrant of her right breast for 2 months. The mass had been palpable for 1 week before the initial assessment. According to radiological evaluations, the tumor is outside breast tissue and not connected to the bones. Hence, a biopsy of the mass is done. The biphasic morphology of the tumor during pathological evaluation, in addition to immunohistochemistry testing, confirms the diagnosis of extraskeletal mesenchymal chondrosarcoma (EMCS). Finally, the mass was surgically removed, and 6 months of chemotherapy were administered to the patient.

Conclusion: Given the tumor's rarity and the lack of established guidelines, diagnosing EMCS can be challenging and prone to errors. As such, meticulous sampling, along with precise pathological and imaging investigations, is imperative to accurately establish the diagnosis of these tumors.

Keywords: biphasic pattern; extraskeletal; mesenchymal chondrosarcoma; tumor.

FIGURE 1

Primary soft tissue chest wall mesenchymal chondrosarcoma with biphasic pattern in a 38‐year‐old woman. (A) Axial non‐contrast CT shows a mass (arrow) in the right hemithorax under pectoralis muscle and inseparable from the second rib with a distinct calcified (central) and non‐calcified (periphery) components. (B) The chest X‐ray determined a well‐defined mass with intralesional rings and arcs calcification which is the near ribs.

FIGURE 2

Gross images of resected specimen. (A) The tumor is tightly wrapped and seems to have a firm, flexible consistency. (B) The longitudinal section of the excised mass reveals a solid and fleshy appearance with focal cystic change.

FIGURE 3

(A) H&E ×20: Malignant biphasic mesenchymal neoplasm with a well differentiated hyaline cartilage component (abrupt transition). (B) H&E ×20: Solid sheets of undifferentiated small blue cells. (C) H&E ×200: Solid sheets and strands of undifferentiated small blue cells mixed with islands of mature appearing, well differentiated hyaline cartilage. (D) H&E ×200: Cellular sheets of undifferentiated small blue cells with frequent mitotic activity. (E) IHC, ×200: CD99, membranous staining in tumor cells. (F) IHC, ×200: Vimentin, positive staining in tumor cells. (G) IHC, ×200: Ki67, high proliferative index. (H) IHC, ×200: NSE, positive staining in some tumor cells. (I) IHC, ×200: FLi1, negative.