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Pericytoma With t(7;12) and ACTB-GLI1 Fusion

Reevaluation of an Unusual Entity and its Relationship to the Spectrum of GLI1 Fusion–related Neoplasms

Kerr, Darcy A. MD*; Pinto, Andre MD*; Subhawong, Ty K. MD; Wilky, Breelyn A. MD; Schlumbrecht, Matthew P. MD§; Antonescu, Cristina R. MD; Nielsen, G. Petur MD; Rosenberg, Andrew E. MD*

The American Journal of Surgical Pathology: December 2019 - Volume 43 - Issue 12 - p 1682–1692
doi: 10.1097/PAS.0000000000001360
Original Articles
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The entity “pericytoma with t(7;12)” was described as a rare, distinct perivascular myoid neoplasm provisionally classified within the family of myopericytic tumors that demonstrates t(7;12)(p22;q13) translocation with resultant ACTB-GLI1 fusion and biologically was felt to behave in an indolent fashion. However, a recent study showed that tumors with this and similar translocations may have variable morphology and immunohistochemical phenotype with inconsistent myopericytic characteristics and a propensity for metastasis, raising questions regarding the most appropriate classification of these neoplasms. Herein, we report 3 additional patients with tumors harboring t(7;12) and ACTB-GLI1 fusion. The tumors arose in adults and involved the proximal tibia and adjacent soft tissues, scapula and adjacent soft tissues, and ovary. All tumors were composed of round-to-ovoid cells with a richly vascularized stroma with many small, delicate, branching blood vessels, where the neoplastic cells were frequently arranged in a perivascular distribution. Both tumors involving bone showed histologic features of malignancy. By immunohistochemistry, all tested tumors were at least focally positive for smooth muscle actin (3/3) and CD99 (patchy) (2/2), with variable staining for muscle-specific actin (2/3), S100 protein (1/3), epithelial membrane antigen (2/3), and pan-keratin (1/3); all were negative for desmin and WT1 (0/3). The 2 patients with bone tumors developed metastases (27 and 84 mo after diagnosis). Whether these tumors are best classified as malignant myopericytoma variants or an emerging translocation-associated sarcoma of uncertain differentiation remains to be fully clarified; however, our study further documents the potential for these tumors to behave in an aggressive fashion, sometimes over a prolonged clinical course.

Departments of *Pathology

Radiology

§Obstetrics and Gynecology

Medicine, Division of Hematology-Oncology, University of Miami Miller School of Medicine, Miami, FL

Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY

Department of Pathology, Massachusetts General Hospital, Boston, MA

D.A.K. and A.P. contributed equally.

Present address: Breelyn A. Wilky, MD, Department of Medicine, University of Colorado School of Medicine, Aurora, CO.

Presented in part at the 108th Annual Meeting of the US-Canadian Academy of Pathology, National Harbor, MD, March 2019.

Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article.

Correspondence: Darcy A. Kerr, MD, Department of Pathology and Laboratory Medicine, Dartmouth-Hitchcock Medical Center and Geisel School of Medicine at Dartmouth, Borwell Level 4, One Medical Center Drive, Lebanon, NH 03756 (e-mail: darcy.a.kerr@hitchcock.org).

Online date: September 17, 2019

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