Spindle Cell Sarcoma

Even in uncommon locations like the thigh, DFSP should be considered in cases of chronic, atypical skin lesions. For the best results, interdisciplinary care, extensive excision, and early diagnosis are essential.

A multidisciplinary approach combining radical surgery and adjuvant RT is crucial; however, the rapid distant progression highlights the critical need for more effective systemic treatment options and the integration of genetic profiling to guide personalized therapies. Further comprehensive research is essential to optimize management strategies and improve the limited survival outcomes associated with this rare and challenging malignancy.

We report a case of mandibular ssRMS with FUS-TFCP2 fusion treated with the third-generation ALK inhibitor Lorlatinib, resulting in a marked clinical response. We also review the potential utility of ALK-targeted therapies in managing FUS-TFCP2 fusion-positive ssRMS and support further exploration of ALK inhibition in this subset.

This case underscores the importance of integrating molecular diagnostics into the evaluation of atypical spindle cell tumors, particularly those presenting with aggressive clinical features despite low-grade histology. Early identification of NTRK fusions enables timely initiation of TRK inhibitor therapy, offering durable disease control and functional recovery. Broader awareness and implementation of molecular testing can greatly enhance the management of rare pediatric sarcomas.

In children with NTRK fusion-positive sarcomas, upfront TRK inhibition yielded faster, deeper responses and eliminated mutilating surgery in our cohort. These data support TRK inhibitors as preferred neoadjuvant options, particularly to facilitate non-morbid resections and to avoid functional disability.

Awareness of its histologic and immunophenotypic features is critical to avoid misdiagnosis and overtreatment. Accurate recognition may prevent unnecessary radical surgical or oncologic interventions.

Notably, the presence of cartilage foci within a RMS-like neoplasm represents a strong clue to an underlining DICER1 alteration. The rarity of this presentation in the nasal fossa at this age, coupled with its implications for diagnosis, treatment, and familial screening, emphasizes the need for awareness of the morphology patterns of DICER1-associated neoplasms across diverse anatomical sites.

Immunohistochemical staining, crucial for characterizing soft-tissue tumor differentiation, revealed diffuse positivity for SOX10 and S100 protein, consistent with a primary nerve sheath tumor rather than metastatic disease. This case highlights the diagnostic challenge posed by FDG-avid lesions in patients with a history of malignancy, underscoring the importance of considering rare differential diagnoses and pursuing tissue diagnosis when imaging is equivocal or clinical presentation deviates from expected metastatic behavior.

This case presents the diagnostic challenges in ALK-positive neoplasms. Superficial soft tissue tumors associated with ALK include a heterogeneous group of lesions that may share similar morphological features. We believe that a generic term, ALK-Rearranged Superficial Mesenchymal Neoplasms (ARSMN), may serve as a more inclusive diagnostic label for these entities in routine pathology practice.

The expression of p75NTR has not been described in this tumour entity before and its significance with regard to tumour promoting or tumour suppressing function or indication of a neurogenic differentiation remains undetermined. After a 3-year follow-up the dog was clinically healthy, indicating a successful surgical treatment.

However, genetic sequencing identified the NRAS Q16R mutation both in the nodule and underlying congenital nevus, leading to the diagnosis of a proliferative nodule composed of poorly differentiated melanocytes. Despite the limited use of molecular biology in the diagnosis of atypical proliferative nodules, it may be helpful in some challenging cases.

LLTs should be considered in the differential diagnosis of vulvar soft tissue masses. Accurate histopathological and molecular evaluation, combined with appropriate surgical management, ensures favorable outcomes and helps avoid unnecessary interventions.