Diagnostic challenges in synovial sarcoma: a case report

Synovial sarcoma (SS) is a rare, aggressive malignant neoplasm with a high rate of metastasis despite its indolent nature. A distinct SS18::SSX fusion oncogene characterizes SS. The monophasic subtype is the most common and consists of spindle cells. Due to its rarity and subtle clinical presentation, SS can be challenging to identify, leading to misdiagnosis or delays in treatment. The present case highlights the importance of awareness and vigilance among healthcare providers when encountering slow-growing, seemingly benign soft-tissue tumors.

A 43-year-old Haitian man experiencing homelessness with a history of psychiatric disorder, tuberculosis, and substance use presented to the emergency department with right leg pain and intermittent chest pain. Physical examination revealed a large, tender mass on his calf, initially considered benign in past encounters. However, further imaging (CT and MRI scans) showed a large 14.3 cm, lobulated, heterogeneous soleus intramuscular mass with multiple peripheral and internal calcifications suggestive of soft-tissue sarcoma. In addition, a CT chest revealed multifocal pulmonary nodules highly suspicious for metastatic disease. Histologic examination of lung biopsies showed cells positive for vimentin, BCL-2, and TLE-1, consistent with monophasic SS; molecular confirmation of the SS18::SSX fusion was not obtained. Systemic AIM chemotherapy (doxorubicin, ifosfamide, and mesna) was planned. However, the patient declined further care and was lost to follow-up. He was subsequently reported to have died from pulmonary complications of metastatic disease approximately 6 months later.

This case highlights the complexity of diagnosing SS, given its subtle clinical findings, slow growth, and atypical presentation. Multidisciplinary care is essential for optimizing diagnosis and treatment outcomes. Prompt recognition and comprehensive care can improve patients' prognosis.