Morphologically Malignant Nodular Fasciitis With COL3A1::USP6 Fusion and a TP53 Mutation.

Area of Science:

• Oncology
• Pathology
• Genetics

Background:

• Nodular fasciitis is a soft tissue tumor common in young individuals.
• Most lesions are benign, but rare aggressive or malignant variants exist.
• USP6 gene rearrangements are characteristic of nodular fasciitis.

Purpose of the Study:

• To report a rare case of nodular fasciitis with malignant features in a pediatric patient.
• To highlight the diagnostic complexities and genetic alterations in unusual cases.
• To emphasize the importance of multidisciplinary management for challenging diagnoses.

Main Methods:

• Histopathological examination of an excised facial mass.
• Molecular analysis for gene fusions and mutations.
• Clinical correlation of findings.

Main Results:

• A pediatric facial mass exhibited nodular fasciitis with marked cellular pleomorphism and atypical mitotic figures.
• Molecular analysis revealed a COL3A1::USP6 fusion and a TP53 Y234C mutation.
• The findings suggest a potentially aggressive or malignant variant.

Conclusions:

• Facial masses require a broad differential diagnosis, including rare malignant entities.
• Genetic alterations like USP6 fusions and TP53 mutations can occur in nodular fasciitis variants.
• Multidisciplinary evaluation is crucial for managing complex pediatric soft tissue tumors.