Spindle Cell Sarcoma

It also underscores the critical role of immunohistochemistry, particularly STAT6 staining, in distinguishing SFT from histologic mimics. Vigilant follow-up remains essential, especially in atypical or CD34-negative cases, given their potential for aggressive behavior.

This case highlights the critical role of molecular testing in the diagnosis of LGFMS and emphasizes the importance of appropriate management strategies, including aggressive local control and long-term surveillance, given the tumor's risk of late recurrence and distant metastasis.

However, adjuvant chemotherapy significantly led to better overall survival. The Hippo pathway is frequently deregulated (nuclear YAP/TAZ in 61.4% of patients), suggesting it is a compelling novel therapeutic target for this aggressive disease.

By sharing the diagnosis and treatment process of this patient and reviewing the relevant literature, we aim to help clinicians enhance their understanding of two rare diseases, namely pleomorphic RMS and sarcomatoid carcinoma of the liver.

While many morphologic features of vascular lesions at this site are shared with those of extra-genital soft tissues, pathologists must be aware that these tumours may occur in the vulvovaginal area and display unconventional clinical profiles. As such, a broad differential for epithelioid and spindle cell neoplasms at this site is prudent.

Concurrent comprehensive genome profiling (FoundationOne® CDx) confirmed the LMNA-NTRK1 fusion, and treatment with the TRK inhibitor larotrectinib was started. With larotrectinib treatment, the tumor shrank in size at an early stage, and the response has been maintained for > 2 years.

This study suggests that pan-TRK immunostaining may be useful for confirming neural differentiation in MPNST. However, whether its positivity reflects NTRK rearrangements or neural differentiation must be carefully assessed in combination with various immunohistochemical and molecular tests.

This case demonstrates the critical role of immunohistochemistry in confirming synchronous primary tumors. For complex, locally advanced disease, radical upfront en bloc resection remains the gold standard for achieving curative-intent, negative margins, even in the elderly.

Despite aggressive pathology, no metastases were identified, and the patient remained recurrence-free at 6 months postoperatively, with chemotherapy reserved for recurrence or metastasis. This report emphasizes the diagnostic challenges, surgical complexity, and clinical significance of primary renal fibrosarcoma and highlights the importance of including it in the differential diagnosis of large renal masses with vascular involvement.

Recognition of gene fusion signatures not only enhances diagnostic precision but also opens avenues for targeted therapy in selected cases. Continued molecular investigation and case accumulation are necessary to validate the biological behavior and therapeutic implications of many of these newly recognized entities.

The patient underwent wide surgical excision with negative margins and recovered uneventfully. This case emphasizes the importance of maintaining synovial sarcoma in the differential diagnosis of deep thigh masses in older adults, where imaging and molecular confirmation are essential to avoid misdiagnosis and treatment delay.

These findings emphasize the need for standardized diagnostic protocols, including routine Rb evaluation and MDM2 analysis, to ensure accurate classification. Future studies should explore the significance of MDM2 expression in ASPLT and reassess its anatomic predilection to refine diagnostic criteria and clinical management strategies.