Round cell tumor with a myxoid matrix harboring a PHF1-TFE3 fusion: Myoepithelial neoplasm or ossifying fibromyxoid tumor?

Fei Fei, Carlos N Prieto Granada, Shuko Harada, Gene P Siegal, Shi Wei

Pathology, research and practice 2021 Sep

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Myoepithelial tumors arising in soft tissue are uncommon and mostly manifest a benign clinical course, although a malignant form does exist. An EWSR1 gene rearrangement is a common event in these tumors. Ossifying fibromyxoid tumor, a rare soft tissue neoplasm of uncertain differentiation, may have overlapping histologic and immunophenotypic features with myoepithelial tumors, but frequently harbors a PHF1 gene rearrangement. Interestingly, a PHF1-TFE3 fusion has been recently reported in both entities. Here we report a case of a malignant soft tissue tumor demonstrating myoepithelial differentiation and harboring a PHF1-TFE3 fusion. Despite being slow-growing and lacking significant cytologic atypia at initial presentation, the patient deteriorated rapidly with local recurrence and distant metastases. A discussion of the potential clinicopathologic implications of a PHF1-TFE3 fusion in these entities is also developed. Copyright © 2021 Elsevier GmbH. All rights reserved.

Citation

Fei Fei, Carlos N Prieto Granada, Shuko Harada, Gene P Siegal, Shi Wei. Round cell tumor with a myxoid matrix harboring a PHF1-TFE3 fusion: Myoepithelial neoplasm or ossifying fibromyxoid tumor? Pathology, research and practice. 2021 Sep;225:153578