Periosteal Myxoid Leiomyosarcoma Histologically Mimicking Extraskeletal Myxoid Chondrosarcoma: Report of a Case with Histopathological and Cytopathological Comparison with Extraskeletal Myxoid Chondrosarcoma

Myxoid leiomyosarcoma (MLS) is a rare variant of leiomyosarcoma, with most cases occurring in the uterus. A case of MLS arising in the periosteal region of the tibia, mimicking extraskeletal myxoid chondrosarcoma (EMC), is described. The evaluation included histological and cytological comparison with EMC. The patient was a 77-year-old man with a palpable mass at the anterior aspect of the right lower leg. After diagnosis by cytopathology and biopsy examination, a wide resection was performed. The resulting cytological smears were composed primarily of spindle-shaped tumor cells in a myxoid and hemorrhagic background. Histologically, the tumor showed abundant myxoid matrix and tumor cells proliferating in a cord-like to reticular pattern, exhibiting a lace-like arrangement that mimicked EMC. Although immunohistochemical findings suggested leiomyosarcoma, a diagnosis of EMC eventually was excluded by the lack of a split signal when assessed for a rearrangement of NR4A3 by chromogenic in situ hybridization. Despite histological similarity to EMC, characteristic cytological findings of EMC such as epithelioid structures with a cord-like pattern and chondroblast-like lacunar structures were not observed in the smears of this patient’s MLS. We propose that cytopathological examination of bone and soft tissue lesions is useful as a diagnostic tool in similar cases. A total diagnostic workup, including clinical, radiographic, cytopathological, histopathological, and molecular findings, is needed to ensure an accurate final diagnosis and to reduce diagnostic error.

Sustained response to imatinib in patient with extraskeletal myxoid chondrosarcoma and novel KIT mutation

A 55-year-old woman presented with a 3-month history of right groin swelling, discomfort and impaired mobility. On examination, a palpable mass was noted both to the right of midline in the lower abdomen and in the right groin. MRI of the pelvis showed two masses involving the anterior abdominal wall and right groin, as well as lymph node involvement. CT imaging revealed multiple bilateral pulmonary metastases. Pathology demonstrated a myxohayline stroma morphology. Tumour was also notable for NR4A3 gene region rearrangement and mutation in KIT exon 11 at position c.1669 T>G. Based on these findings, she was diagnosed with extraskeletal myxoid chondrosarcoma (EMC). The patient has been on imatinib, a tyrosine kinase inhibitor with activity against KIT, for 3 years with stable disease. Metastatic EMC is generally treated with surgical resection and perioperative radiation therapy with adjuvant chemotherapy and is associated with poor prognosis.

Extraskeletal myxoid chondrosarcoma of thigh: a rare case report

Extraskeletal myxoid chondrosarcoma (EMC) are a rare entity of soft tissue tumors that occur predominantly in soft tissue of lower extremities. Here we present a case of 45-year-old female presented with left thigh swelling. MRI finding suggested primary neoplastic lesion. Fine needle aspiration cytology (FNAC) suggested myxoid soft tissue neoplasm/sarcoma. Morphological examination revealed typical extraskeletal myxoid chondrosarcoma with strong immunoreactivity for vimentin and focal immunoreactivity for epithelial membrane antigen (EMA).

Primary Extraskeletal Myxoid Chondrosarcoma: A Case Report

Extraskeletal Myxoid Chondrosarcoma (EMC) is a rare malignant soft tissue sarcoma with uncertain differentiation, most often seen in males. The incidence is 3% of all soft tissue tumours with limited literature available on its cytological features. EMC may arise from lower extremities, upper extremities, retroperitoneum, pelvis, and buttocks. This case report was an effort to understand the role of Fine Needle Aspiration Cytology (FNAC), histopathology and immunochemistry in the diagnosis of EMC. Authors hereby report a case of a 70-year-old male patient with slow-growing soft tissue swelling on the back just behind the right shoulder who was referred for FNAC. Patient complete history and clinical findings were recorded. Radiological images were suggestive of malignant soft tissue neoplasm with no involvement of underlining bone. FNAC reveled tumour cells which appeared monotonous and they were seen in a myxoid stroma background. Subsequently, the excised lesion was sent for histopathological examination and the report revealed the presence of abundant chondromyxoid matrix material within which were found numerous elongated spindly shaped cells. These cells had moderately pleomorphic elongated nuclei with focal solid fibrocollagenous areas along intersecting fascicles of the moderately pleomorphic spindly cell. Few of these cells had multilobulated bizarre nuclei with nuclear inclusions. Immunohistochemical stains showed diffuse positivity for S-100, vimentin, and focally positive for Epithelial Membrane Antigen (EMA). The FNAC, histopathology and immunohistochemical features confirm the diagnosis of EMC on right shoulder. It’s a rare tumour whose diagnosis is made depending on history, clinical location, growth pattern, histopathology, and immunohistochemistry.