Endobronchial Pulmonary Angiomatoid Fibrous Histiocytoma

Abstract

Angiomatoid fibrous histiocytoma (AFH) is a rare soft tissue neoplasm of intermediate biological potential, predominantly occurring in the extremities of children and young adults. It has only recently been reported as a primary lung tumor. We describe 2 cases arising endobronchially harboring EWSR1 gene rearrangements by fluorescence in situ hybridization and, respectively, EWSR1-CREB1 and EWSR1-ATF1 gene fusions by reverse transcription polymerase chain reaction. Histologically, both tumors showed classical features of AFH, comprising multiple nodules of bland spindle to epithelioid cells surrounded by lymphoplasmacytic inflammation and at least a partial fibrous capsule. Both tumors showed focal but strong desmin immunoreactivity, with focal pancytokeratin and epithelial membrane antigen in 1 case. The lung is now a recognized site of AFH occurrence, but tumors arising here can be associated with different gene fusions. It is important to recognize AFH in the pulmonary region, as its behavior at other sites is generally relatively indolent; however, it may be mistaken for metastatic or more aggressive primary lung tumors. It is likely that cases of AFH in the lung may have been previously missed because of their morphologic and genetic overlap with other pulmonary lesions.

EWSR1 Fusions With CREB Family Transcription Factors Define a Novel Myxoid Mesenchymal Tumor With Predilection for Intracranial Location

“…10 Despite desmin negativity and lack of lymphoplasmacytic cuff, PPMS show some histologic overlap and similar genetic features with AFH, raising the possibility of a pulmonary myxoid variant of AFH. 11,12 A somewhat similar scenario is the GI clear cell sarcoma, a term initially proposed by us in keeping with a variant of soft tissue CCS lacking melanocytic differentiation, 3 but refuted by others, who suggested instead a novel entity designated as malignant gastrointestinal neuroectodermal tumor (GNET), possibly originating from a GI neuroectodermal precursor cell which has lost or does not have the potential to differentiate along the melanocytic lineage. 13 Some of these controversies stem from the uncertainty on how translocation events drive phenotypic variations, and larger datasets are needed to clarify their status as independent pathologic entities.…”

A Subset of Malignant Mesotheliomas in Young Adults Are Associated With Recurrent EWSR1/FUS-ATF1 Fusions

“…Although rare in the thoracic or abdominal cavity, angiomatoid fibrous histiocytomas have been reported at these sites, harboring EWSR1-ATF1 fusions (40). Additionally, rare cases with endobronchial or pulmonary presentation have been described (41, 42). However, angiomatoid fibrous histiocytomas typically stain for desmin, while being consistently negative for cytokeratin.…”

Recurrent Angiomatoid Fibrous Histiocytoma of thigh in a middle aged female: A case report

“…Chen et al reported clear cells, rhabdomyoblast-like cells, pulmonary edema like pattern and myxoid stroma in some AFH cases [5]. Bohman et al have reported perineurioma-like pattern, moderate pleomorphism, significant areas of sclerosis, eosinophils in the stroma [12,13] [12,16] while consistently negative for S100 protein, CD34, CD35, CD21 and Cytokeratin. Our case shows immunopositivity for desmin, EMA and CD68.…”

“…Our index case was seen in 40 years woman with a recurrent thigh mass measuring 6 cm in maximum dimension. Microscopically, it is characterized by varying proportions of spindled or histiocytoid cells, arranged in a nodular pattern, pseudovascular spaces and prominent lymphoplasmacytic rim [12,13].…”