Open AccessRecurrent YAP1-TFE3 Gene Fusions in Clear Cell Stromal Tumor of the Lung
Author(s) -
Abbas Agaimy,
Robert Stoehr,
Michael Michal,
Petros Christopoulos,
Hauke Winter,
Lei Zhang,
Albrecht Stenzinger,
Michal Michal,
Gunhild Mechtersheimer,
Cristina R. Antonescu
Publication year - 2021
Publication title -
the american journal of surgical pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.625
H-Index - 210
eISSN - 1532-0979
pISSN - 0147-5185
DOI - 10.1097/pas.0000000000001719
Subject(s) - pathology , tfe3 , perivascular epithelioid cell , biology , fusion gene , clear cell , histogenesis , stromal cell , hemangioblastoma , pleomorphism (cytology) , epithelioid hemangioendothelioma , immunohistochemistry , medicine , epithelioid cell , gene , gene expression , biochemistry , promoter
Clear cell (hemangioblastoma-like) stromal tumor of the lung (CCST-L) is a recently described distinctive rare pulmonary neoplasm of unknown histogenesis and molecular pathogenesis. Only 7 cases have been reported in 2 recent studies, although additional cases might have been reported under the heading of extraneural pulmonary hemangioblastoma. We herein describe 4 CCST-L cases, 3 of them harboring a YAP1-TFE3 fusion. The fusion-positive tumors occurred in 3 women, aged 29, 56, and 69 years. All presented with solitary lung nodules measuring 2.3 to 9.5 cm. Histologically, all tumors showed similar features being composed of relatively uniform medium-sized epithelioid to ovoid cells with clear cytoplasm and small round monomorphic nuclei. Scattered larger cells with enlarged hyperchromatic nuclei and marked pleomorphism were noted in 2 cases. The tumors were associated with a hypervascularized stroma with variable but essentially subtle resemblance to capillary hemangioblastoma and perivascular epithelioid cell tumor (PEComa). Immunohistochemistry was negative for all lineage-specific markers. Targeted RNA sequencing showed a YAP1-TFE3 fusion in 3 of 4 cases. All 3 tumors showed homogeneous nuclear TFE3 immunoreactivity. Two patients were disease free at 36 and 12 months. The third patient had biopsy-proven synchronous renal and hepatic metastases, but extended follow-up is not available (recent case). The fourth case lacking the fusion affected a 66-year-old woman and showed subtle histologic differences from the fusion-positive cases, but had comparable TFE3 immunoreactivity. CCST-L represents a distinctive entity unrelated to hemangioblastoma and likely driven by recurrent YAP1-TFE3 fusions in most cases. The relationship of our cases to the recently reported "hemangioblastoma-like" CCST-L remains to be determined. Analysis of larger series is paramount to delineate the morphologic spectrum and biological behavior of this poorly characterized entity.