Intracranial Myxoid Mesenchymal Tumor/Myxoid Subtype Angiomatous Fibrous Histiocytoma: Diagnostic and Prognostic Challenges

BACKGROUND AND IMPORTANCE

In the setting of intracranial neoplasms, EWSR1-cAMP Response Element-Binding Protein (CREB) transcription factor family fusions have been described in myxoid mesenchymal tumors, extremely rare entities with a close histopathologic and immunologic resemblance to myxoid subtype angiomatoid fibrous histiocytomas (AFH). Controversy exists on whether these central nervous system lesions are a subtype of myxoid AFH or a completely separate entity, which entitles a distinct clinical behavior and, consequently, a different approach to management. Upon review of the literature, only 14 cases of intracranial tumors harboring an EWSR1-CREB family fusion were identified, with only 3 cases presenting in middle-aged adults, none of which reported an EWSR1-CREM fusion mutation. Significant variability in reported radiographic and histopathological characteristics, as well as in clinical outcomes, was noted. Their similarity with other soft tissue tumors, added to the scarce information on its clinical behavior, represents a great diagnostic and therapeutic challenge to the treating physician.

CLINICAL PRESENTATION

We present a rare case of EWSR1-CREM mutated intracranial myxoid mesenchymal tumor/myxoid subtype AFH presenting as persistent headaches in a 36-yr-old woman with radiographic evidence of rapid growth and extensive vasogenic edema, for which she underwent surgical resection.

CONCLUSION

This represents a unique case of EWSR1-CREM mutated intracranial myxoid mesenchymal tumor presenting in adulthood, with evidence of aggressive behavior.

Intracranial myxoid mesenchymal tumor with EWSR1-CREB1 fusion

Myxoid mesenchymal tumor with predilection for intracranial location harboring EWSR1 fusions with CREB family transcription factors is a recently described and exceedingly rare neoplasm. While some debate still exists whether this is a true separate entity or a myxoid variant of angiomatoid fibrous histiocytoma, these tumors still deserve separate attention due to localization, fairly distinct histology and higher incidence in the pediatric population. Data regarding outcome of these neoplasms are still sparse in medical literature. We report a case of an intracranial myxoid tumor with EWSR1-CREB1 fusion in a 14-year-old girl.

Intracranial Myxoid Mesenchymal Tumor With EWSR1-ATF1 Fusion

Angiomatoid fibrous histiocytoma (AFH) is a rare soft tissue tumor that arises primarily in the extremities of young adults. Recurrent gene fusions involving EWSR1 with members of the cAMP response element binding protein (CREB) family have been reported in a diverse group of tumors, including AFH. AFH-like lesions have been reported to occur intracranially and the reported cases show low proliferation indices, frequently have a connection with the dura, and show recurrent EWSR1 rearrangements. These tumors have been termed intracranial myxoid mesenchymal tumor with EWSR1-CREB family gene fusions. A literature search identified 11 reported cases of intracranial AFH-like lesions with an EWSR1 rearrangement. Here, we report a case of intracranial myxoid mesenchymal tumor with an EWSR1-ATF1 fusion in an adult patient, and review the existing literature on this recently described entity.