Primary pulmonary clear cell sarcoma-the first two reported cases.

Area of Science:

• Oncology
• Pathology
• Genetics

Background:

• Clear cell sarcoma, also known as melanoma of soft parts, is a rare soft tissue sarcoma.
• Primary lung sarcomas are uncommon, making their diagnosis and classification challenging.

Observation:

• Two male patients, aged 50 and 55, presented with primary lung tumors.
• Histological examination revealed clear epithelioid and spindle neoplastic cells in storiform and nested patterns.
• One case exhibited regional lymph node metastases.

Findings:

• Immunohistochemistry showed positivity for S-100 protein, HMB-45, and Melan-A in one case, and S-100 protein in the other.
• Fluorescence in situ hybridization confirmed EWSR1 gene rearrangement.
• Reverse transcription-polymerase chain reaction (RT-PCR) and sequencing identified the EWS-ATF1 fusion transcript in one case.

Implications:

• These findings contribute to the understanding of clear cell sarcoma as a potential lung neoplasm.
• The study highlights the utility of immunohistochemistry and molecular techniques in diagnosing rare lung sarcomas.
• Further research is warranted to elucidate the specific behavior and treatment of clear cell sarcoma in the lung.